Hey guys,

I want your opinion and experience on this one. I got these codes, took the car to the dealer, and they decided to change my spark plugs with new ones. I drove out the lot, tried to go up in the RPM's... same issue occurs and CEL comes back. I'm going back to the dealer on Monday to drop the car off for more serious diagnostics.

Going back, in the past 3.5 months of ownership of this new car, I've had been back 3 times for CELs. I've gotten P0103 (MAF Intake too much air), P0300/P0302 Misfire on Rotary chamber 2, and now P0300, P2097 (Air/fuel too rich), P0172 (System too rich).

To describe what's happening... it feels like beyond 4000 rpm, if you are at light throttle... you feel the engine sputtering and hesitating. However, if you give it more gas, it goes away and spins up. It's most pronounced in 1st gear, and gets less pronounced as you go up to 6th gear. Mind you, it's still present in 6th gear, since if I cruise at 135 km/h or so... in 6th gear it's just around 4200rpm or so.. you can feel the car hesitating and stuttering, but it keeps driving. It's like as if there is some throttle chopping going on.

I have looked at all the threads concerning those DTC codes listed; but I want to know some real world experiences that you guys may have come across in your ownership with the 8.


I have several speculations
a) does this have anything to do with the brutally cold temperatures we have this winter in Toronto?
b) does it have to do with me having the MS CAI, so at speeds the air going into the intake isn't stable?
c) all the salt/snow/sand combo we've been getting in Toronto entering the CAI and making it dirty real fast? (I do have the sock installed).
d) These problems never existed in the first 1.5 months of ownership, though temperatures were much warmer then. Is the RX-8 not revvable in very cold temperaures?

The car has been running on nothing but V-power 91, and I do check/top off engine oil with Castrol GTX 5W20. I am very worried about the longevity of the car now. I've been treating it really good ever since mechanically and cosmetically... and seems like it's just not reciprocating the love :(

I have an issue of a similar nature. Ever since I added the RP supercat to my system I have been getting P301 (i think) misfire in Rotary Chamber #1. I sometimes get a little hesitation with a grumbling noise from the motor as I accelerate hard in a high gear 5/6th from about 4000rpm.

I believe dirt on the filter has a lot to do with it (i have athe RB w/air duct) especially in the winter time. I think otherwise the problem is 2 fold.

1) the CAI can really pack a lot of air into the intake at high speed and I think this causes the air to back up from the motor and fool with the MAF readings by flowing across it.

2) the size of the exhaust and the change in cat may be screwing up the 02 readings or putting them to a spec the car can't adjust to.

You obviously don't have the same parts but may be having a similar problem. Depending on your mileage I would also recomment putting in new coils and plug wires. I put in RB plug wires and noticed a smoothness improvment.

hope this helps.....

http://www.rx8club.com/showthread.php?t=135546&highlight=compression

How's the idle? Smooth or rough?
How does it start? Right away or cranks too long?

It starts right away. Idle's smooth.

It starts right away. Idle's smooth.


Then I wouldn't worry about the motor being bad yet. When the CEL comes on does it stay on?

It flashes then stays on. Then I floored the car to redline in 2nd gear, and then shift, and redline in 3rd gear, and it flashed again.. and then stayed on.

So it went from flashing --> on ---> after 1 minute later, I decided to floor it and then it went flashing ---> on.

It flashes then stays on. Then I floored the car to redline in 2nd gear, and then shift, and redline in 3rd gear, and it flashed again.. and then stayed on.

So it went from flashing --> on ---> after 1 minute later, I decided to floor it and then it went flashing ---> on.

Sometimes one problem may result in conditions that will trigger other codes. Try to narrow down what code is the source of the real problem. Reset the code by disconnecting the battery for a minute. Run the car again and check the code as soon as the CEL comes on.

My guess (and only a guess) is it's the MAF sensor.

you can hear the car throttle sound like someone is chopping it.. like there's some air turbelent sound from under the hood...

This only happens under load? What happens if you rev it up in neutral (no load)? Does it rev up smoothly? Reset the code and rev it up in neutral, does the CEL come on when you rev up in neutral?

the CEL is on now... I can't reset it without going to the dealer. I'll wait till Monday to see what happens. They changed my spark plugs today. They will take my car in on Monday and do a full diagnostics in detail.

I will rev it tonight when I get off work in neutral to see what happens at higher RPM's in terms of the "throttle chopping" phenomenon.

Man that sucks!
Have them check the plug wires and MAF sensor

I have a hiflo cat and mazdaspeed cai...no cels at all.......its a car by car basisis with this vehicle.....my car has been good to me, others haven't had an experiance as good as mine. I have heard of people getting cels from the cai but it does sound like an issue becasue of the cai, maybe a maf sensor issue.....have you tried to clean your maf sensor??? it could be restricting the amount of air its letting in making your car run a little rich??? just guessing but its worth a try.

Ok guys,

I drove it around for 45 minutes so it's all warmed up. I revved it in neutral, and its sputters past 5000rpm... so it can't possibly be too much cold air rushing into the CAI... something else is wrong.

Hvnsnt, any ideas? dirty MAF (on a 3.5 month car)??? faulty O2 sensor?

spark plugs??? coils??? maf??? I would check those.......and yeah your car is 3.5 months old....but you never know. worth a checking a few things before the dealer makes you sign your life away.

I had the same problem on my car... it came from the CAI when it's cold and you have some water on the filter itself....

Since I don't drive the car as much so after I parked the car for a few days and the CEL went away by itself....

It sucks in the winter where the air filter is located right behind the grill and water/salt/dirt get on it very easily... I don't know, maybe put the stock intake back on for the winter??

I got new plugs already yesterday. So perhaps new coils and new maf?

From the previous codes I got, anything to do with the O2 sensors and catalyst?

hmmmm......I have the same part and dont have those problems........and I have even had ice frozen over my filter at one point when we had a large snow fall one day........i dont think a little bit of water or a damp filter would cause your engine to sputter above 5000 rpm???Rockstar probably knows a little more than I do about mazdas as he was a manager but I still dont see how this would cause this problem....you are still getting as much or more flow with the cai with a wet filter as you would with a stock air filter........you wouldn't be bringing water into the engine...the air would be " humidified " if anything......which shouldn't cause this......again I am just guessing and by no means an I a mazda mechanic.........I am just saying that if this was the actual problem then we would all be experiancing it...I definately would have as my filter was almost completely covered by ice and gets damp/wet all the time as well. You should have enough air flo, why else would your engine sputter??? poor combustion, lack of spark.....maybe the wet filter is the problem, but I just dont have it on my car with the same/ worse condition air filter.

it could be coincidental but, a lot of other people are having this issue and replacing their coils fixed the problem.........again, could be a coincident but might not be??

So it does sputter after 5k rpms in neutral? Start with changing the cai back to stock. I don't think it would be the O2 sensor. The O2 is not a factor under load conditions which is when you got the CEL.

Hope you get this worked out Footman.

I can't perform the intake swap myself. I have an appointment with the dealer on Monday to get it all sorted out. I can suggest to him what I think (but I don't want to piss off the technician with my input, cause that's like "stepping on his toes" kinda thing for his job).

If the car is stopped and I rev and it sputters. How would the CAI be the factor? cause no wind is blowing into the car, the air input should be consistent at rest (no turbulence)?

P2097 and P0172 both talk about running too rich, and possible O2 sensor failure... oh man, I feel bad that no one else in Toronto is getting that. I hope it's just cause the weather is too cold or something... It didn't do this in November when I first got the car and the temps were above 5 degrees.

Now the windchill everyday is like - 15 or more!

personally I dont think its your intake......seriously....pull out the maf from the intake and see if there is any debris on it, something is limiting the amount of air in your engine to make you run too rich.......checking the maf is a 30 second thing...unscrew it and pull it out and look at it. if its not that then you will be looking at something possibly more expensive to fix. Its not the weather.....I live in kingston and its always a little colder or the same temperature here that it is in toronto. then take a look at your throttle body.....take the intital pipe off the intake and see if you can move the valve inside.....maybe its stuck??? there are a lot of things that it could be....but I doubt its your intake.

I don't have any brake cleaner. Can I use compressed air (the stuff to clean computers) and blow inside?

How can a MAF get so dirty in 3.5 months?!?!?!

How can a MAF get so dirty in 3.5 months?!?!?!

If there is a leak in the CAI after the filter....

If there is a leak in the CAI after the filter....

+1.....good call......footman, did you install the cai or did the dealer??? if the dealer did, they could have had oil all over their hands when they were reinstalling the maf...you never know......its plastic, just use a clean soft towel and wipe it off........it just makes sense that something is limiting the air going into the engine....and the maf is what controls the amountof air entering......try it.

I will stop by partsource or Canadian Tire and pick up some electrical cleaner or that CRC MAF cleaner stuff if they have it. I'll take a look at the CAI. How often should I clean the CAI intake filter? When I got the car, I also got 2 bottles of filter cleaner. The CAI was installed by the dealer.

I know it's slightly different for RX-7's, but I've never had that problem occur.
I did notice that my car will not run in temperatures below 7C. I think my intercooler does a very good job of cooling the air. The computer cuts fuel at around 6000rpm.
That's when I knew it was time to put the car away.

You'd be surprised what the MAF sensor goes through. A good cleaning on everything will make a big difference.

Aside from that, I would think it's the CAI that might be causing the trouble at high RPM.
I know other people have said they haven't had the same problems. But have they experienced the same temperatures we've experience here in the last little bit???

Maybe a stuck injector? although you said the car is running richer, right?
That's definiately a trial and error situation. Sucks, but that's all part of the character of the car. ;)

CAI and MAF problems go hand-in-hand.

The oil gets on the MAF because of the huge air volume our car takes, high velocities and potential to strip the foam of it's oil.

When you get the cleaner, make sure to shoot some up INSIDE the top of the 'tube'. The tiny wires up there are the actual 'maf' sensor.


S

Canadian Tire nor Partsource has CRC MAF sensor cleaner, and I asked the guy at the partsource about using air intake cleaners and he says it will damage the MAF sensor if I use that. Anyone know where to buy CRC MAF cleaner in GTA?

sorry to hear you having troubles andrew, my guess it's the CAI causing MAF to get dirty. bad idea to run the CAI in Canadian winters

BTW, did I say this is my daily driver? and Toronto's winter has been very very brutal this season.

So does anyone know where to buy CRC MAF cleaner in GTA area?

The AEM/MS intake is has an oiled filter right? Its probably because of that.
________
AlishaAndJack (http://camslivesexy.com/cam/AlishaAndJack)

no its a dry flo filter....and if it was an oil issue, then the k&N should technically do the same; which it doesn't. footman, did you clean the maf sensor yet??

No, I didn't yet. I couldn't find CRC MAF cleaner at Canadian Tire nor at Partsource. I'm in Toronto, and I don't know where else I can go to try to get it.

I don't want to use brake cleaner or carb cleaner; just want to be on the safe side and use something properly designed to clean MAF.

SUCCESS.. I was able to find CRC MAF cleaner. In Canada it's branded as "SensorKleen".

FYI people, I found it at Napa Autoparts store in Scarborough. It is located on Birchmount Rd. south of Eglinton on the west side of the street.

I got the last one they had in stock and more are coming in.

I will post my results of MAF cleaning this evening.

Okay guys, here are the results.

I used CRC MAF cleaner, and cleaned the MAF. I drove her around for 15 minutes to warm her up. Once warmed up I brought her on the highway. Throughout the drive... I was able to maintain 2nd gear at up to 6000rpm or so with no problems around 70km/h..... once I got on the highway... I floored it. Goes to redline in 2nd gear, goes to redline in 3rd gear no problem. This is with the gas pedal all the way down. The exception is that, the CEL light starts to blink, and then goes away each time I do this. I did it several times to redline and downshift, and it goes.

The sputtering starts when I try to hold it at a certain speed above 6500 rpm. For example, if I try to maintain 90 in 2nd gear.. .it sputters.. if I try to maintain 120 km/h in 3rd gear, it sputters lightly.

Cleaning the MAF seemed to have helped a lot. When I got back to my place, I decided to test it in neutral. I revved it to redline, it goes there, but as I go above 6000rpm, the CEL blinks again. If I hold it steady below 6000rpm, it's fine. Above that, if I try to hold it there, you can feel it sputtering. Eventually the CEL blinking stopped and this time, it stayed there.

One important thing to note: There is NO sense of LOSS OF POWER at all. It pulls perfectly fine throughout all of this.

I pulled out my SCANGAUGE II, and now I only have P0300 misfires.

Intake temps are between 0 to 10 deg Celcius. I washed the CAI sock and double checked and it looked clean as well.

So now I have the following done:

1) MAF cleaned
2) Spark plugs replaced

P0300 remains. Ambient temperature is -4 degrees today in Toronto.

What do you guys think?

P.S. The correct hex key size to remove th RX-8 MAF is 9/64". It took me 3 trips to the mall to figure that out.

An excessively lean mixture may cause misfiring. Be careful not to push it too hard. The MAF signal may be inaccurate enough to cause a lean condition.

I don't think it's an ignition problem because there appears to be no issues below 6K, and under no load, the ignition should work the same whether it's above or below 6k. Plugs could be too cold though.

Excellent post; You're very thorough.
You should pull out the plugs and check the colour (take a picture), check that they're the right parts and check that they were installed in the right locations.

so your air fuel is too rich???? I guess you need to start working your way along trouble shooting. So you aren't getting enough air into the engine.......you cleaned the maf and it helped, and you cleaned the aor filter. did you check the throttle body valve??? could be stuck or not opening fully...ie. could have gummed up oil or dirt making it not open up fully. if that doean't help, you are going to have to have the dealer look at it I think.........but I agree with hevnsnt that it probably isn't an iginition issue...but I personally would check the coils anyways.

sorry I am also going to add this ......not to insult you as you didn't install the cai right??? are the 3 hoses attatched to the 3 prongs on the intial pipe of the cai???? if one of them is not on correctly, you could be pushing air out of there???? just putting it out there...........one of mine popped off under hard driving once and since then I have used hose clamps around each one of them and around the vfad plug......your plug is on the vaccuum port on the throttle body, right??

No insult taken Gecko69, I'm a noob so any help is appreciated.

I did not install the CAI; the dealer installed it.

What you said is a little bit over my head after I read it. Can you elaborate some more? I couldn't find a DIY on MS CAI or AEM intake here, so I could not reverse the process of installation to understand what you are saying with respect to the vacuum ports or VFAD plugs or the 3 prong plugs?

Darkbrew,

Pulling the plugs is too much for me to do. I live in a condo, and I don't have a jack to work on the bottom of the car. Plus, I don't have most of the proper tools (i.e a socket wrench) to perform these steps. Regardless, I will be dropping off the car tomorrow morning for a full day. The dealer apologized for not solving my issue after 3 visits for CELs and said they will do a full diagnosis and they're giving me a loaner car for a day.

hey footman. SO I am at work other wise I would have e-mailed you the picture on the instrutions. SO I will explain the best I can.

when you look at the CAI in your engine bay( while you are facing in from the front of the car ), the very first section of tubing coming off the throttle body has the MAF port and before that there should be 3 prongs with black tubes attached to them........they all have different functions, but they all should be over the prongs and pushed down to the bottom of the prongs.....if any one of them were off or almost off you could be leaking air out of the port.

Secondly, move to the drivers side of the car and look into the engine bay and at the bottom of the throttle body on the side you can see there is a conection for the vaccuum tube used for the stock intake that was taken off when the stock air assembly was removed. this little prong needs to have a cap/plug over it. this should have been included in your cai kit and installed by the dealer.

take a look at those to see if they are attatched and covered respectively.

I checked.

The 3 pront black tubes are secured all the way down. They are clamped on with plastic ties already.

I'm not sure which is the throttle body, but to describe what I think I saw.... the first block that the CAI is attached to looks like that throttle body. Standing on the drivers side of the hood and looking at it, at the lower section of it, I see a round opening that has a cap covering it. I wonder if that's what you are talking to. It's capped off and looking around, there are no free-hoses that are dangling with caps on it or looking disconnected.

yeah.....then everything is capped.......its a prong that sticks straight down from the side/bottom of the throttle body ( silver metal that the first peice of the cai attaches to ) it's noticableable....should be covered with a black soft cap. its not a round opening.....its a prong...looks just like what the top hoses are attatched to but smaller.

http://www.rx8club.com/showthread.php?t=122529&highlight=cai+pics

here is a pics....the small black tube to the right of the cai with the small white connector( exactly right of the cai and right below strut bar ) leads just up behind the throttle body and connects to a small prong...that is where there should be a cap...

I looked, I could not find that hose you were talking about.
Here are some pics of my CAI in engine bay.

ok....good pics......in the third pic.......do you see the green and white plastic thing under the throttle body. That is a part of the vaccuum tube that connects to the vaccuum port on the throtle body. It looks like they tucked it under the throttle body.....either pull that tube out from under there and check to see if they put a black cap on the end or if they secured it/tied it down...foloow it and see if they capped it. that same tube should come up to a port just behind the throttle body. as long as they capped it then your ok. if there is no cap...you will need to get one. Not saying this will fix the problem completely, but it should help.

Okay, that tube, goes from one port to another port! It isn't coming out from one port and then "capped off". In between the two ports, the hose has a green/white thing attached to it.

I'm going to give up today.. i went to start the car and it threw a second code: P0411
I'm going to let the dealer handle it tomorrow for the full day.

yeah....jeez.....dont know what to tell you. good luck at the dealer..hope they fix it for you.

No one mentioned the screens in front of the MAF sensor. Can you confirm that the screens are in place?

The screens are in place in front of the MAF. I saw them when I removed the MAF to clean yesterday.

Such bad experience with a brand new car only 3.5 months :(

It makes me feel slightly better that over at the 350Z forums, they have similar problems too:

http://www.my350z.com/forum/showthread.php?t=327166
http://my350z.com/forum/showthread.php?t=307878

Ha Ha

all cars have problems, and performance cars have more.

i personally enjoy working on my car, every time there’s and issue i look forward to diagnosing it and correcting it.

Left the car this morning at 8am with the dealer. Just picked it up and drove home now. They replaced the ignition coil. I ran it through the RPMs... seemed to do the trick. Looks like the coils went bad; will monitor though since the drive is short home. I'm crossing my fingers that tomorrow, a longer drive to and from work will yield NO CEL's or awkward sputtering at high RPMs.... really really crossing my fingers. I feel bad.

My question now to y'all is... aside from possible "manufacturer defect" of the ignition coils on a 3.5 month old car, what could possibly go wrong to have caused it if it wasn't a defect? Are there any particular bad habits of driving that would cause ignition coils to prematurely fail?

Speculation time.
I think that the coils can be damaged by excessive heat but I doubt that you got into that situation. Another possibility could be a partially bad spark plug wire putting too much load on the coil and causing it to overheat.
Get some decent plug wires when you have some spare money...

I doubt excessive heat. It was stil warm for about a month when I got the car in beginning of October. But warm is like 20 - 25 deg, not HOT. After that it's been downhill dipping into as cold as -15 in Toronto.

They didn't change the plug wires though. Now I have new plugs, new coils, but factory wires. If that is the culprit.. the coils will fail very soon too then and I'll be back in the shop in another few months!

Speculation time.
I think that the coils can be damaged by excessive heat but I doubt that you got into that situation. Another possibility could be a partially bad spark plug wire putting too much load on the coil and causing it ti overheat.
Get some decent plug wires when you have some spare money...

Really??? me and a few other guys on the board go down to Mosport every month in the summer and I haven't heard anything about a bad coil... but maybe that's just me...

I do drive the car pretty hard when it's on the track and none-stop for about a 25-30 mins session so it must get pretty hot~ even with a test-pipe, the car doesnt even give me a CEL for the O2 sensor... the only time the CEL was on was when I ran outta gas!! lol

And there was some other codes that I was getting when I stored the car in the summer, and every time the dealer tells me it's a vacu. leak and replaced at least 4 gas caps... and then they suspected it was an air tank leaking.... but after I stop checking for the leak it just went away... I guess the car just doesnt like those grease monkeys from the dealers!! :spank:

Damn coils. Never would have thought it'd be this.

Really??? me and a few other guys on the board go down to Mosport every month in the summer and I haven't heard anything about a bad coil... but maybe that's just me...

I do drive the car pretty hard when it's on the track and none-stop for about a 25-30 mins session so it must get pretty hot~ even with a test-pipe, the car doesnt even give me a CEL for the O2 sensor... the only time the CEL was on was when I ran outta gas!! lol

And there was some other codes that I was getting when I stored the car in the summer, and every time the dealer tells me it's a vacu. leak and replaced at least 4 gas caps... and then they suspected it was an air tank leaking.... but after I stop checking for the leak it just went away... I guess the car just doesnt like those grease monkeys from the dealers!! :spank:

I don't think any Canadian 8s have had an overheating issue with the coils but the coils do fail at some point. How many km on your car?
Maybe your ECU just gave up... :lol2:

They didn't change the plug wires though. Now I have new plugs, new coils, but factory wires. If that is the culprit.. the coils will fail very soon too then and I'll be back in the shop in another few months!

Just buy some new ones from RB or Mazsport and remove the possibility...

coils, coils, coils, it's always the bloody coils!

my car is 3.5 months old and has 6600km on it.

I don't think any Canadian 8s have had an overheating issue with the coils but the coils do fail at some point. How many km on your car?
Maybe your ECU just gave up... :lol2:

Well my car only has about 47,000km since 04... and come to think about it, even tho the engine light isnt on but the car does jerk sometimes... so you think that's the coil problem??

I still have the bumper to bumper warranty till end of this year, if that's the case I'll bring the car back in to the dealer and get it replaced...

I can't even fathom how a brand new car ends up with bad coils, unless somebody at the dealership needed four coils in a pinch and took the good ones off your car before you bought it.

me neither.. but nonetheless the coils "somewhat" solved it.. I can't say it's 100% solved, cause now it maybe weather related?....

seems like REALLY cold air + CAI is not always a good thing..

Has anybody been able to "hold their throttle" and cruise around 7000 - 8000rpm without any blinking CEL's?

I can go WOT to redline and shift, and there's no problems. But if you ask me to go towards redline at medium throttle, somewhere along 7000 - 9000 rpm, it sputters a bit and CEL starts to flash. The only remedy is either let go of the gas, or floor it and let it go to redline and then shift and it's okay...

yeah i can drive between 7-8k with no cel's only did it for like a min or 2 thu

Do you have a MS CAI?

So sad...
P0300 and P0172 came back on today, sputtering between 6500 - 9000rpm remains at any throttle other than WOT.

Recap:
a) new spark plugs last week
b) new ignition coils on Monday (but not wires)

Same question I want to ask you all:

"Has anybody been able to "hold their throttle" and cruise around 7000 - 8000rpm without any blinking CEL's?"

I'll try it out tonight.

I get a CEL in that range also, P0301, which I believe is misfire in rotor 1. No one including me has been able to track it down. I have new plugs, coils, and Racing Beat wires. The car seems to run fine though, but does lag a bit on the top end. Its hardly noticeable.

"Has anybody been able to "hold their throttle" and cruise around 7000 - 8000rpm without any blinking CEL's?"

Are you asking just those that have MS CAI installed or anyone? If you're asking just anyone, I have no issues like this.

You must have been the one at Scarborough Mazda last week. I was there Friday getting a new starter. One of the receptionists there told me someone had been in with their engine light on. I've been in on and off since last November trying to get my hard start issue fixed (thankfully, it's now fixed). Victoria (receptionist) and I are on a first name basis now:cool: .

Victoria, Michael, Paul, Russ, are all on first name basis now with me at Scarborough Mazda. Yes that's my car sitting there. That day they changed the ignition coils.

I am only asking everyone to try it to hold the revs between 7000 - 9000, whether you can do for even more than 15 seconds with no stuttering, CEL blinking, and just pure smoothness...

Then let me know whether you have an MS CAI or not. Thanks everyone.

I get a CEL in that range also, P0301, which I believe is misfire in rotor 1. No one including me has been able to track it down. I have new plugs, coils, and Racing Beat wires. The car seems to run fine though, but does lag a bit on the top end. Its hardly noticeable.


So what do you do? you just drive around and try to avoid high RPMs?

My car has the SAME issue ONLY when it's raining out... and I was guessing that's the water getting into the filter~

When it's dry it'd never have a problem getting/ staying in that RPM range with a CEL

Hey Footman I did check it out today, I don't have my mazdaspeed intake in yet, but ya, no cel, and held it steady for 15 seconds, no cel. Guess its gotta be the intake.

The intake didn't cause this issue before. Also, Mazda wouldn't approve that for Mazdaspeed application if it causes this regularily. Let's see if other forum members can prove it. Thanks for your response.

i have the K&N drop in filter, i dont have any cell's at high rpm even when held for extended periods of time. i've had the coolant light come on once before thu. im assuming i just need to add some coolant.

The intake didn't cause this issue before. Also, Mazda wouldn't approve that for Mazdaspeed application if it causes this regularily. Let's see if other forum members can prove it. Thanks for your response.

I agree. P300 and P172 is misfire and system too rich. Likely, a single problem is causing both to ocurr. The rich fuel could be causing plug fouling which is causing the misfire.

The question is, does this occur under load (open loop) or no load (closed loop) conditions or even part load. You said there is no problem when you floor it to redline. The problem seems to occur under part load (moderate throttle to redline). Try reving moderately to redline in neutral, 1st, 2nd to 4th. Does this happen in neutral and all gears?

It's back in the dealer yesterday. This time, I got the master mechanic to ride with me and I showed him my symptoms. The car is still in the shop right now; preliminary, he suspects it's a bad CAT because the problem only occurs between 6000 - redline. He explains that if the cat is clogged, there will be a lot of back pressure and thus the engine isn't able to breathe right since the exhaust gases are backing up into the combustion chamber.

At WOT, the force of pumping is sufficient enough to overcome the current blockage; hence at light to medium throttle I am getting extreme sputtering in that range because a moderate throttle isn't generating enough force to expel the exhaust.

Because the engine detects knocking from the exhaust gases backing up into the intake/combustion of the next cycles in the rotary engine it isn't able to properly ignite because the mixture is contaminated, it throws a P0300 code. The unburnt fuel is further dumped into the Cat causing the P2097 Catalyst fuel trim - system too rich, which is also tied to P0172 system too rich.

This is the preliminary analysis.

Recap:
1) Spark plugs replaced
2) MAF sensor cleaned
3) Ignition coils replaced
4) verified that MS CAI filter is clean and dry (sock is clean)
5) verified that all vacuum hoses from MS CAI are not loose
6) idle is good, RPM range from 0 - 5000 is usable smoothly.
7) mechanic has tested the stock plug wires for leaks and deterioration and they checked out okay; so they were not replaced.

sucks if its your cat....they are 1400+ from the dealer...but at 31/2 months you mat be covered??? I just sold my stock one a while back.........but if you do have to replace it it give you a really good excuse to but an aftermarket one.

If it is the CAT, it has to be covered by warranty. At 3.5 months, I'm not even out of the complimentary 12 month free-adjustment period yet!!! let alone the 3 year - 80,000 bumper to bumper.... YET LET ALONE the 120,000 emissions component warranty!!! ahahahahahaha

Actually if it's any part failing now.. it should be 100% warranty covered.

Dealer called to tell me that the CAT is tested fine.

They said the MS CAI is not designed for cold weather and this happens only in winter when it's cold.

My options now are to:

A) Keep the MS CAI and drive below 5000rpm until weather is warmer, thus every winter, I cannot drive it above 5000rpm.

B) Put the stock intake back on should fix the problem.


This is my all year round car. What do you guys think? I have to use this car to get to work, I have no other car to use.

isnt warranty wonderful.

I think your dealer is just trying duck out of finding out what the problem really is with your car by blaming the performance add on. I have a 2007 RX-8 that I got last february. I had the mazdaspeed CAI installed in april since they didn't have those performance packages in yet. I still drive my car in the winter and there is no stuttering or CEL flashing in the 6000-9000 rpm range. I can drive in that range anywhere from very low throttle to very high throttle (and everything in between). I've only tried it in 1st and 2nd gear, but the car does drive fine. I have some very small sputtering in first around 8000 rpm with low throttle but when I moved up to moderate throttle it went away.

It can't be or shouldn't be the CAI. If it's not doing it for me it shouldn't be happening to you. I dunno what to say but it may be related to something else.

Oh and just to make it even more relavant, I also live in Scarborough (Markham and Lawrence) so weather conditions are IDENTICAL to where you are. Hope that helps. Any more questions let me know.

P.S. My car has 15,400 Km

Well,

What I'm going to do is change the stock one back in, and have the mechanic test drive it with me right there once its done to verify that's the issue.

I asked if they've done a compression test, and they said they didn't because no problems were found relating to it. I asked can they do it, and they said no.

If after the stock intake is back on, and it still does that... man I don't know what could be wrong

Recap:
a) Spark plugs changed
b) Ignition coils changed
c) Plug wires tested OK
d) CAT tested OK
e) MAF cleaned
f) MS CAI air filter verified to be clean and free of water/ice on sock
g) MS CAI blamed for problem due to extreme cold weather and is not good for engine

Amkorp, does it have to do with the fact you have the MS Dual can exhaust and I don't? Would the MS dual can exhaust match the breathability at the back end of your engine to your MS CAI in the front because I only have the CAI, but stock exhaust.

Hmm, that's a good question. Your dealer first stated that the issue was in your CAT and then in your CAI. Both those items are well before the exhaust piping.

But then they also said your CAT was ok. So it may be related to exhaust restriction. However, that would be a design flaw on Mazda's part, seeing as they were going to sell this car in our climate as well as offer the CAI to us, I really don't think they were expecting all owners to buy a dual can mazdaspeed exhaust as well, that's just stupid. You shouldn't be having this problem even with the stock exhaust.

But like you've mentioned, you'll know for sure after installing the stock airbox.

I've got a questions for you, when you hit the rpm range that is giving you problems, are the RPMs bouncing up and down or do the RPMs stay constant but you lose power?

the RPMs bounce up and down.. you hear a chopping sound, like something fluttering...

again, this is between 6000 - redline at light - medium throttle. The ONLY remedy while you're in that zone is to give it more gas, in which it will jump to the next "maintainable rpm" at that throttle position.. (i.e. stuttering at 6400rpm.. suddenly jolt it with more pressure and hold the higher throttle, then it will go to 7500rpm, and then stutter there.

However you can FLOOR it anywhere between those RPMs, and it will go straight to redline *somewhat smoothly* and the you shift.

As long as you aren't holding the throttle around 6000 - redline, you will not get a blinking CEL. It only happens if you try to hold it in that range, not even for 5 seconds, and it will stutter and CEL flashes.

I don't think it's the cat. Even if the cat was clogged, it didn't clogg itself, some other problem would have caused it to clogg. And because your car is practically new I doubt it's a clogged cat.

Under light throttle/cruise conditions, the car is in closed loop condition. Fuel enrichment is fine tuned according to O2 sensor readings.

Under moderate/wide open throttle conditions, the car is in open loop condition. Fuel enrichment is predefined (preprogrammed) based on mapping of the throttle position and MAF readings.

Is the problem occuring in closed loop (light throttle) or open loop (heavy throttle)?

the problem primarily occurs in light and medium throttle.. I keep saying this!

I think the computer is the one not feeding enough fuel into the car with light/medium throttle.
As you mentioned, if you give it more fuel it'll go up and move into the next mappable range.
I honestly have no idea why you would be running the car at such high revs and maintaining it at that level???
How often do you do this? Do you actually drive around town always in the upper range???
Most of the time people shift between 4000-5000rpm, sometimes earlier.
Rarely do people hold the throttle very lightly in the 6000-9000rpm range. Most of the time they have the throttle pinned to the floor and the computer is dumping as much fuel as it can into the car.

These suckers serge in light throttle with normal weather conditions.
So you can imagine what it's going to do when the weather dips below 0C.

If you want to keep the CAI on the car, then you'll have to learn not to drive lightly in the 6000-9000rpm range. Or you can simply install the stock air intake and be done with it. Possibly swap out the element with a K&N or something like that.

I think exposing the intake directly to the elements is a bad idea if you're going to be running the car all year long.
It's great during the spring/summer/fall months. But winter comes around and now you have slush and ice hitting the intake. Regardless of it being protected or not.

Since this is your year-round vehicle, I would install the stock air intake box and switch out the element.

I'm sure there'll be buyers for the CAI. :)

the problem primarily occurs in light and medium throttle.. I keep saying this!

O2 sensor, MAF, TPS

That's my guess, in that order.

I think your dealer is just trying duck out of finding out what the problem really is with your car by blaming the performance add on. I have a 2007 RX-8 that I got last february. I had the mazdaspeed CAI installed in april since they didn't have those performance packages in yet. I still drive my car in the winter and there is no stuttering or CEL flashing in the 6000-9000 rpm range. I can drive in that range anywhere from very low throttle to very high throttle (and everything in between). I've only tried it in 1st and 2nd gear, but the car does drive fine. I have some very small sputtering in first around 8000 rpm with low throttle but when I moved up to moderate throttle it went away.

It can't be or shouldn't be the CAI. If it's not doing it for me it shouldn't be happening to you. I dunno what to say but it may be related to something else.

Oh and just to make it even more relavant, I also live in Scarborough (Markham and Lawrence) so weather conditions are IDENTICAL to where you are. Hope that helps. Any more questions let me know.

P.S. My car has 15,400 Km

I think just because you don't have the problem that doesn't mean it's not the CAI... as of right now none of us know exactly what the problem is...

the RPMs bounce up and down.. you hear a chopping sound, like something fluttering...

again, this is between 6000 - redline at light - medium throttle. The ONLY remedy while you're in that zone is to give it more gas, in which it will jump to the next "maintainable rpm" at that throttle position.. (i.e. stuttering at 6400rpm.. suddenly jolt it with more pressure and hold the higher throttle, then it will go to 7500rpm, and then stutter there.

However you can FLOOR it anywhere between those RPMs, and it will go straight to redline *somewhat smoothly* and the you shift.

As long as you aren't holding the throttle around 6000 - redline, you will not get a blinking CEL. It only happens if you try to hold it in that range, not even for 5 seconds, and it will stutter and CEL flashes.

I still suggest you to have the stock air-box put back in and see how it goes...

All the moisture that is coming in through the intake to the engine just can't be that good. That's also why after a few years of making cold-air-intakes AEM started making those AIR BYPASS VALVES to prevent water and moisture getting into the engine...

just my 2 cent

everyone just wait for me on Monday.. I just dropped off the stock intake and VFAD components with dealer. They said they do not have time to install it on Saturday, so they will install on Monday. I will pick up on Monday night and test drive with them to verify that indeed stock intake fixes the problem.

Also note.. weather forecast says monday is raining with 3 deg C temps.

I tried running mine around 6000 rpm with light throttle. No issue at all.

I tried running mine around 6000 rpm with light throttle. No issue at all.

not "around 6000rpm"... I've been very specific when I say, to hold your throttle between 6000 - 9000 rpm for more than 30 seconds with no hiccups...

don't vary the rpm's while in that range either... lets use an example.. hold your engine while driving... at 7200rpm (randomly picked)... for 30 seconds.

Ok. What I did was hold just over 6000 RPM for about 10 seconds but I can try what you suggest. It seems weird to do this...

Ok. What I did was hold just over 6000 RPM for about 10 seconds but I can try what you suggest. It seems weird to do this...

Well, did you try it?

Yes I did and it felt really odd to do it. How did you discover this? What gear were you in?
Anyway, my car didn't misbehave.

Okay, I'll explain how I come to this. First let me lay some facts...

One of the selling points of the car is its incredibly high rev range and the fact that it can be revved that high without much ill-effect. I didn't buy this car to use it between 0 - 6000rpm. I bought the car to use it from 0 - 9000rpm.

6000 - 9000 usage example:

-> You're not always lucky to be the first car in the lane entering the highway on ramp. There's usually some bloke that is slower than you. So you would most likely be in 2nd gear, inching your way towards 80 - 90km/h (average ramp entrance speed). You would hold that gear until the ramp section completes, and the lane allows you to cut into the highway. That is when you gun it to redline, and then shift, and redline, and then shift again.... ending at around 148 km/h and then slowing down to a more cruisable speed of 120km/h while you shift from 4th to 6th.

Okay, I'll explain how I come to this. First let me lay some facts...

One of the selling points of the car is its incredibly high rev range and the fact that it can be revved that high without much ill-effect. I didn't buy this car to use it between 0 - 6000rpm. I bought the car to use it from 0 - 9000rpm.

6000 - 9000 usage example:

-> You're not always lucky to be the first car in the lane entering the highway on ramp. There's usually some bloke that is slower than you. So you would most likely be in 2nd gear, inching your way towards 80 - 90km/h (average ramp entrance speed). You would hold that gear until the ramp section completes, and the lane allows you to cut into the highway. That is when you gun it to redline, and then shift, and redline, and then shift again.... ending at around 148 km/h and then slowing down to a more cruisable speed of 120km/h while you shift from 4th to 6th.I guess that makes sense

Hey Footman, I hope the stock intake fixes your problem but if not, I would still put the doubts on the CAT.

It seems like you drive your car hard, and at light throttle at high rpm, the exhaust temps could be very very high, (not excessively rich like WOT and high rpm AND with the rotary engine) which is bad for the CAT.

They said they tested the CAT, but I doubt they've taken it out. I can't dig it up for you, but the dealership's CAT test isn't always accurate, I have seen that several times on this board already over the years.

Since you've replaced the coils, you've eliminated another weak component in the car. The CAT is what you should check next, consider taking it to a garage to have them take a look inside the CAT if dealership can't solve the problem for you.

I hope this helps.
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I'll find out Monday night and I'll post here, when I pick up my car tomorrow evening afterwork.

I got my car back tonight, again the drive back home is really short and with rush hour traffic, can't really try out those ranges. I managed to redline once in 2nd gear, no blinking CELs, perfectly smooth.

Soundwise.. that grunt is entirely gone :(. Do take note that I bought the car with the MS CAI installed already, so from the get go, I was used to that awesome sound when you go full throttle.

It's all gone now... all gone... it's so sad, she sounds like a whiney bitch now. I dunno, maybe it'll take some time for me to get used to it. All those fun sounds when you floor it as it spools up those RPMs is completely gone.... I'm depressed.

The MS CAI is now sitting in my trunk... I will have a full confirmation whether the intake was truly the cause of the problem by tomorrow night. I need to drive some mileages first to try out the ranges to make sure no more blinking CEL's at high RPMs... I'll update y'all for sure.

This will be better for you.
You can't afford to have the car down for 1 day. This is your only means of transportation.

So what if the car doesn't sound like a rotary anymore. At least you know you won't have to worry about it the next time you fire it up.

it's actually "drivable" with the MS CAI in the winter. just that my effective RPm range is 0 - 6000rpm only.

That still sounds like a bandaid. I hate how dealerships are always trying to do the bare minimum. They shouldn't even call the people who work on your car mechanics. The rest of us with CAIs are driving in the same winter weather as you without the problem you're having. That's BS that they just took it off and called it fixed.

yeah I know... I'm not 100% satisfied, but what can you do? so far the stock intake does seem to have fixed the problem the CAI caused...

If it isn't the true cause, eventually it'll creep back up again someday. Is anyone willing to go through the bumper removal DIY with me in person? Someone experienced with that and the CAI intake install? I'm tempted to put it back in for the summer; but I don't feel very confident doing it myself without any guidance.

Do a few searches in the forum, some have posted the instructions here. Also Check the workshop PDFs online somewhere. After looking at that should give u a good idea of what tools, time, and how to take it off. It shouldn't be that hard, and if you feel comfortable with it go for it! You have a good few months to get ready for this install.
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I have a friend that suggested that the MAF values need to be reset? Remember that I am sputtering between 6000- 9000rpm even in neutral with the CAI installed, but no such problems with the stock intake. Seems like it's strictly an airflow issue?

That little piece of mesh filter inside the tube.. is it supposed to be installed at an angle?

I guess the biggest part about re & re ur stock air-box and CAI is to remove the bumper... other than that it's nothing fancy... I'll help you when it comes time in the summer... not a big deal~

Well well well... I examined my CAI in 2 pieces in the trunk. The long straight section which the MAF is installed, in that tube has two mesh screens, but tehy're all bunched up in awkward angles and they are about 2 inchs in front of the MAF location stuck together!

Are the mesh filters supposed to fit snuggly with the CAI such that removal will not change their position? If so, then that means the mesh screens are like this in my car all the time; and they weren't dislodged during the removal. Is that normal?

I will post HIGH RES pics tonight. Please help me out guys.

Hey footman, I just read through your issues and it sounds like you may have found what was actually causing the problems. try to get some pictures tonight so I can see the way your screens are positioned. I don't know how to describe this....if you take the section of tube and set it with one end on the ground, the ring of mesh should be parrallel with the ground. I will look through the instal guide to see if there is a pic of it...

And just for reference, I have the aem year round just north of chicago and I was driving with it a couple weeks ago when it was -5 F. I have gotten a CEL flashing a couple misc times around 8000 rpm but those are rare and go away after I back off.


EDIT
Alright, so I looked at the install guide and it doesn't show a pic fo the screens directly, but it did remind me of installing mine and how the screens worked! With the AEM the screens sit in the couplers between the peices of pipe. There is a ridge in the coupler so you place the screen in front of the ridge so that when air flows into the engine the screen is pushed against the ridge and not back towards the engine.

If the MS intake is set up the same way and someone put the coupler on backwards, then the screens could have been blown back in the tube that houses the MAF. The screens shouldn't be in the tube of the MAF at all. One should be just in front of that tube in the coupler and the other should be in the coupler in the next pipe down the line.

Since I can't send you the install guide right now, here is a screen shot of it. This should clarify what I just said. Look at steps 'f' and 'g'

When Darkbrew asked me a few pages back when I was cleaning my MAF whether the screens are there. I looked inside the MAF and saw the screen exactly in the same position as I see this now. Though I did not count how many screens were there as I didn't know there are two screens in the MS/AEM CAI.

Now that it's disconnected, this is what I found. Looking down the barrel, I'm guessin that the screens should fit in those ridges exactly perpendicular to the length of the barrel?

More pics.

1) Could these screens be the cause of my problems?
2) Could it be possible they were installed incorrectly?
3) Could it be that they are installed correctly and they somehow blew backwards towards the MAF? and if so, what could cause that to occur?

Nice pictures man.
The idiots at the dealership didn't think to check the screens???
Well they installed them wrong in the first place so what do you expect...
Well this discovery should ultimately lead to a solution.

so now the problem is.. how do I test my hypothesis? I really need help re-installing the CAI. and if it isn't the problem, then I have to put the stock back in for good. Anyone want to help me out? I'll take you to dinner/lunch whatever.

How about sitting down with the service manager at your dealer... These guys need to take responsibly for this crap

This would be an interesting project.
Wanna make a meet of it?? ;)

well Darkbrew, if I go back now, I have no proof that they did. They could say "you went home and moved it there and tried to blame it on us"... or some bullshit excuse, you know how dealers are like... I'd rather just let this one slide, and go about my own to see if I can learn something from this experience.

Actually, as of this writing... I am disassembling the 3-piece section of the upper tube, so I can re-align the screens properly.

But seriously guys, can anyone shed light on this issue.. can something like this cause sputtering from 6000 - 9000 rpm?

Footman, I'd say yes, it can. The way the screens were placed the airflow to the MAF would not represent the overall airflow.
Neo I'd say that sounds like a great idea. With a few drinks in us we could really take care of Footman's car

with a flat head screwdriver, this took me 20 minutes to do carefully, and aligning the strap tighteners parallel, and the logo straight to make things perfect.

I think I answered a few questions myself. What Aero8 said was right, the black rubber boot that fits in between the sections are ridged on one side such that the screen cannot possibly be pushed back towards the engine. Upon disassembly, I discovered that the rubber boots were installed in the correct orientation, which means the screens must not have been put in there:rant: :spank: :icon_no2:

I installed them correctly, and realized I can bounce a tennis ball off the mesh without having it get dislodged from the ridge; no amount of air can be as forceful as a tennis ball going into this pipe hitting the mesh, so it's impossible for any airflow to dislodge the screen.

Conclusion: Mazda dealer did not install the intake correctly. They forcibly stuffed the two screens into the section of the CAI closest to the MAF such that it just stays in front of it.

Here are pics of how it is supposed to be done.

Question remains: Aero8 has his installed correctly, and has intake temps of -5 F and threw the occasional CEL at high RPMs. Can these screens which were installed in such way that they were 2 inchs from my MAF and at a slant angle of approx 60 degrees from the walls of the tube, in combination with cold temperatures cause the sputtering from 6000 - 9000 rpm?

BTW, with a few drinks in you Darkbrew, you'll be too drunk to do the bumper removal properly! :) and start jabbing the screwdriver missing the screws and hitting the paint!!!

Footman, you say that like it's a negative thing!

BTW, I vote yes on bad screen placement causing your issue.
A flashing CEL at high RPM is a random misfire and doesn't relate to your issue IMO

Footman, you say that like it's a negative thing!

BTW, I vote yes on bad screen placement causing your issue.
A flashing CEL at high RPM is a random misfire and doesn't relate to your issue IMO

No, I do have flashing CEL's at high RPMs...

Just for an update.. it's day 2 with the stock intake... today's temps have been between 0 - 8 degrees C ambient. I redlined several times, and drove between 6000- 9000rpm with no stuttering or blinking CELs.. everything so far is still smooth.

tell them to install it!!!! dealer mechanics don't even read instructions right
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footman, as darkbrew said, the flashing CEL's are just random misfires and the rare times I get them, temp has been all over the board. I should've specified that the flashing CEL wasn't in the cold weather and aren't frequent.

As for your situation. Since you had your car in and out of the shop so many times and you have been talking with the techs, I really think you need to take the CAI back in there, along with the pictures you showed us, and tell them to put it back on for you. Not noticing it the first few times is one thing, but when they had the whole CAI off the car they could have looked in the frickin' tube.

There is no documentation saying the CAI can't be used in cold weather and that was a total lie by them because they couldn't actually fix a problem. They should be set right.

Either way, if you decide to do the install yourself, with two or three people you will have a good time and it will go pretty quick. I did mine myself and while it took me a long time, that was only because I didn't want to jack the car up and take the front wheels off. (won't be that stuborn again)

Good luck!

Hey Footman!
I'm using one of your pictures as my desktop background!
http://www.rx8club.com/attachment.php?attachmentid=114776&stc=1&thumb=1&d=1202260791

That's my facebook profile pic too! I'll send you the full size one if you like.

so things are fixed footman???? I just installed a few things on my car and today on the way to work started getting a flashing cel???? think it has to do with the ap pulley I just installed......I will reset the ecu tonight and see how it goes??there was no loss in power or stuttering so I am not too concerned. but glad to hear things are going better for you in the cel department, or at least you are working towards the answers.

Gecko69.. things appear to be fixed. I drove around this whole week, and even endured the snowstorm on wednesday. The stock intake works perfeclty fine. On the snowstorm day, within 2 hours, I got the P0420 CEL, cleared it and got it again. So I cleared it again, thinking maybe it's just doing stupid shit cause my car was practically eating snow in the front, and I was sliding everywhere (fun-wise). Since the snowstorm on Wednesday, I haven't had the CEL come back again.

I disassembled and re-assembled the CAI PROPERLY putting the screens. I will wait till spring time.. buy the RB screens, and then go to RPM Motorsports, to have them install both at the same time with the bumper off, and test my theory on whether those screens were fucking up all this time.

I am still totally shocked that they were not installed right, and the technicians who had over 48 hours with my car DID NOT DISCOVER THAT. It has significantly made me lose faith in dealer technicians.

well, mazda techs are pssing me off ....when I went to the dealer for a scheduled service, I talked to them about installing the AP pulley and they were ADAMENT that I would have to remove the bolt in the center of the drive belt pulley...that bolt is attatched to the engine internals and would have f%^cked everything up had I removed it.....it baffles me how ridiculous they are here in kingston.....just for fun I asked how long it would take them to install the pulley and they quoted me 3 hours......I laughed and told them they are full of shit and that I could do it in 15 minutes and I did....bastards!!!!!. I am putting the rb screens on now and hopefully that will help, but the car eats alot of snow when lowered with heavy snow.......but I hope things stay ok for you.

WHen I get my Agency Pulleys, will you hepl me install them? 15 minutes? it's that easy?

I would help you or at least give you very detailed instructions on how to do it.......just let me know. Will have to make sure I am off work.There is actually a really good DIY on it ....but I would help if you had any questions. just let me know. The hardest part is putting the new screws in the ap pulley as its a tight area and its tricky. took me 15 minutes to do.......it really is pretty easy.

http://www.rx8club.com/showpost.php?...9&postcount=34

here is the DIY.....was explained well, but if you have any questions. let me know.

I vow to get to the bottom of this. yes I am RELENTLESS like that, but that's just me :)

Tonight in Toronto, the temperatures were -16 C, with 50kph wind gusts, so with the windchill factor, feels like -28 C. Remember I had stock-intake installed right? No stutterings from 6000 - 9000rpm, just smoothness...

I pulled out my Scangauge II, and it reads Intake Air Temperature: -11 C.

Conclusion: what the techs were telling me were a crock of shit/lies with the CAI feeding "too cold" air. As I had sputtering when the IAT's were only -5 C.

New possibilities: Air turbulences causing mis-readings of MAF, hence those damn screens! is all I could think of now that is untested.

P0420 CEL code thrown 4 times in the past week. Cat efficiency below threshold. I bet the CAT eventually got damaged over time from all those misfires... will leave with dealer and see.

Why don't you just remove the cat and run it like every other rotary owner runs it! :cool: ;)

First I must say Scangauge II FTW!!! It has helped me tremendously.

After having 3 CEL's all resetted by me and coming up as P0420; the forth one came and I took it to the dealer. I told them the code, and enthusiastically explained to them what I think is the problem. I let them run it through their own paperwork and procedure and the end result is, I'm getting a new CAT just as I had suspected and diagnosed.

I sent them my pics of the improperly installed MS CAI, and then physically brought the CAI tube and showed them the way it SHOULD have been installed. They are going to issue an internal tech bulletin to the rest of the dealers now to "watchout" for this mistake. I've created a fully documented case with this issue.

This is my new theory on everything from day 1:
1) MS CAI screens incorrectly installed, but the screens were still some distance away from the MAF sensor. Meanwhile, engine was broken-in, thus no high RPM's were in use.
2) Over course of usage, vibrations and wind slowly back the two screens closer and closer to the MAF sensor. Engine fully broken in, begin usage of high-RPMs.
3) At the height of the problem, the two screens were 1" away from the MAF sensor, stacked together, at a 60 degree angle to the MAF.
4) High RPM's usage results in increase sensitivity of air flow across MAF. With the screens now causing buffetting of the air and resulting in incorrect readings. Sputtering above 5000 rpm starts occuring at idle, under load, under all temperature ranges.
5) Incorrect readings cause fuel injectors to dump massive amounts of fuel into the engine causing various CELs citing "system running too rich". Incorrect fuel/air ratio causing misfires.
6) Plugs begin to foul from misfires, plugs replaced.
7) Misfires cause unburnt fuel to be ejected into the exhaust.
8) Excessive unburnt fuel cumulates in the CAT. Front O2 and Rear O2 sensors detect low effiency. CAT dies.

In summary: Incorrectly installed screens --> Incorrect MAF readings --> Running rich --> Misfires --> Plugs fouling --> Unburnt fuel in exhaust --> Raw fuel destroys CAT.


Who could have known two tiny screens could cause so much damage? Will update more as the CAT is being ordered by the dealer, and I'll have it installed next week.

The MS CAI issue has still yet to be verified, I'll wait till spring to re-install the CAI.

BTW, fuel economy has gone up significantly with the stock intake!:)

Okay, the CAT has been changed today Feb 29.

Will monitor for anymore P0420 CEL's.

No more issues with high revs to report =)

If all goes well, I can finally put this issue to rest. Wait for spring, re-install MS CAI properly =)

I think I'm gonna be getting mine replaced too soon. Had my CEL cheched out by WCS last time, and got the same code as you Footman. He cleared it, a week later got a CEL again, went away 2 days after, got a CEL two days ago, went away this afternoon. Came back on again tonight.

I'm so jealous. I want a CEL! I have a dyno graph that shows my cat is restricting flow above 7000rpm but no CEL so the dealership won't help me. Either my sensor is more tolerant or you guys have some super serious screwed up cats.

LoL. On a side note, I just scored a full tank of 91 for the price of 87. Gotta love when gas stations run out of regular gas. But it makes you wonder why they don't offer both 89 and 91, instead of only 91. Kinda makes you think 89 and 91 are the same. I don't know how Esso runs things. This maybe a noob question. But I know that RX-8 J spec wise have 250, well stated that they 250 hp, and we hae 238 cause of out emissions regulations. Would a straight pipe and a retune let me achieve the supposed "250 hp?"

nvm, i got my silly question answered using the magic of SEARCH.

Just a tune should do it. Our emissions warranty lasts 10 years so they had to play it safe with our tune to keep the cat alive that long.

For your gas station conspiracy, I was thinking it's more likely that 87 and 89 are the same but I think people just use up the 87 first then use the 89.

Just like how women need closure to everything, so does Natalia...

Thanks to Gecko69, the improperly fitted screens causing sputtering theory has been tested and verified success.

We installed it at the RPM meet, did some test drives, and on the drive back home to Scarborough, no issues, no CELs.

Let this thread close now, and hopefully when someone else has similar problems, they can refer to this as a guide.

Bottomline: Check your air screens for proper fitment.

Ive got P0420, Low Efficiency in the Cat.

I havent changed plugs yet, though I think they were changed during the 4520F recall. So got a appt at the dealership on Tuesday morning, to check it. So I get the line, ya its covered under your warrnaty, but if we find that spark plugs were the cause of the cel, your paying the service charge.

So, can spark plugs be a cause of this cel, unburnt fuel in the cat. My engine still maintaints its high revs, and notice no sputtering, redline a day without any issues. What do you guys think.

Gonna go pick up a plug socket tomorrow or borrow one to check the plugs out. Will post pics if I can.

I already got plug wires, and waiting to order plugs. Just holding out wiating for the BHR coil upgrade.

Copied this from another thread. I don't think P0420 has anything to do with your spark plugs.

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''P0420 = Catalyst system efficiency below threshold''

It looks as if the ''Hi-Flow'' CAT is not doing its job.
According to the workshop manual the monitoring condition for this CEL are;
1 - ECT = more than 158F
2 - Catalyst converter temp: more than 752F
3 - LOAD = 20 to 50percent (maximum calculated load values varies depending on engine speed)
4 - Time with purge control system does not operate: more than 20s

It also says possible causes are;
1 - Looseness of Front HO2S sensor.
2 - Leakage exhaust gas.
3 - Purge control system malfunction.
4 - VSS malfunction.
5 - ECT malfunction.
6 - Eccentric shaft position sensor malfunction.
7 - PCM malfunction.

Can someone help me please?
I noticed my CEL came on too this morning when driving, it was raining quite heavy as well. I did not accelerate past 4k at any point (Hwy speed)
I currently have the AEM CAI installed, and I can definitely feel the filter is wet.
Is it safe to continue driving at the moment? What should I check to hopefully clear the CEL?

Just a wet filter... no problem, just let it dry, it'll be fine.

Wow after reading all 7 pages, I love it. Same exact problem I'm having. Was told to replace my ignition coils, wires and spark plugs. After that CEL came on again, was told that they found code P0300 through multiple diags. They said they performed a compression test and found two cylinders to have carbon build up. Had it decabarbed earlier and still got the CEL after. Car feels much better but still have that problem between 6-9k RPM. Heading back in the morning to tell them to check my MazdaSpeed CAI. :rock:

Who installed your CAI? Avante Mazda? I think Footman got his from Avante....

Who installed your CAI? Avante Mazda? I think Footman got his from Avante....

Nope had mine installed by Star Mazda. Hoping they got the installation correct.

footman...u leaving the MS CAI on for the winter?

I left my CAI on past winter no problem. It's staying on all year round.

cool! I can't be as bad as last year....I hope!!