bigmac

I have 9000 Miles on my RX-8 and kept it well maintained so far. Occasionally, I run the car at its full potential to stretch its muscles.

I have noticed, that the car choks at higher RPMS (6000 and up). It almost seems like it is asking for either more air or fuel. In a visual representation, one can say the acceleration graph does not seem to be a stright line incline anymore.

The car seemed to have a smooth acceleration incline curve without any hesitation when it had up to 3000 miles.

Just wondering, if anyone else is experiencing the same?

Thanks

HERO

iTrader: (3)

i noticed the same thing... its weird actually.... it runs really well on some days... and then on other days the acceleration just isnt there... seems like its being held back. ( No not climate related... i've already took that into consideration and tested it out....)

HERO

iTrader: (3)

i have a little over 10,000 miles on mine....

Ellar

As long as you're not hearing any funny noises or seeing any warning lights, try clearing the ECU first before taking it to your dealer service department. Sometimes the computer will read something from a sensor that makes it go into sort of a safe mode, and it loads a really uninteresting fuel map.

There are two ways to reset the ECU: Easiest is to get in the car when it's cold, turn the key to RUN without starting it, and tap the brake pedal 20 times within 8 seconds. That's easier than it sounds, believe me. The other way is to disconnect the battery and hold the brake pedal down for a few seconds. The brake lights supposedly drain any residual energy out of the system. You'll have to reset all of your radio presets that way, though.

rotarygod

The auxillary ports open up at 6250 rpm's. If these don't open you will definitely not pull any harder above this point. Don't just assume that you'd get an ecu code if these didn't open. You won't! There is a code for malfunctioning auxillary ports but only if they get stuck OPEN and not closed!!! This is because leaving them open would make your low end emissions change a little but having them stuck closed wouldn't. Who cares right? You or your dealer may not find anything wrong with a diagnostic check since there is no code for them being stuck shut. It's crap but you'll need to check this one the old fashioned way. Get in there and check it yourself. I wonder how many people actually have this issue but dealerships aren't finding anything wrong because of this lack of error code? Trust me, It's all true! I wish it wasn't.

Ellar

How would you go about checking that?

vegas RX8

I've noticed that as well. Mine, along w/ the lack of acceleration, i hear a 'flapping'/'knocking' while stepping on the gas. I took it into my dealer here in vegas (Magic Mazda) last week and they performed what I think was the 'N' flash. I still noticed the lack of power and the flapping on Saturday. I don't get it. In my case, I've noticed that its at the higher rpm's (5K & up) while the A/C is on. I know some of you might think, "There it is, it's the A/C thats sucking all the juice." but believe me it's not. Everyone who listens to/feels their car can tell what feels normal and what doesn't. I have 20k miles on mine and it occurs randomly. The only things i've noticed is the a/c is on, warm outside (85-90 deg.), and at the high rpm's. I read the TSB #01-008/05 for the MSP04 (Mazda Special Program) and one of the listed concerns is what is happening to my car. But like I said, I took it in, had the reflash and it's still doing it. Any insight would be great. Sorry for the long post. Thx. vegas.

zoom44

cats- get your cats checked. and no a cat that is going south does not always trip a cel.

Ellar

Meow?

zoom44

its not just a problem here- although you can do a search and find much discussion here already about it- but also a problem in the uk read it here-

http://rx8ownersclub.co.uk/forum/viewtopic.php?t=7115

Xyntax

I have been experiencing this lately. At 6000 or so, either my car accelerates significantly slower than it should or the RPMs bounce up and down as if hitting the rev limiter. Weird.

rotarygod

Since this does not show up in any diagnostic codes that the dealership or anyone else my scan for, it will require someone to physically check the issue. This is actually fairly easy to do. There is a small electric motor on the lower intake manifold that is fairly easily accessible from the passengers side. Unbolt it and see if you can get it ti spin or do anything when you apply 12 volts to it. Also check and see if the gears inside the manifold where you removed it from turn at all. There is more than one person experiencing this issue but NO dealership can diagnose it by just looking at ecu codes. If they didn't get in there and physically check, they will NEVER find it! I am dead serious. The only code a stuck auxillary port would throw is if it is stuck open. If they are stuck closed and you are losing top end power, it will not throw a code. The reason we can't get any answers is because many techs today are too lazy to get their hands dirty and have absolutely no clue how anything works anymore. They rely on computers. The problem is that if the computer doesn't diagnose every problem and no one told them that it doesn't, they'll never figure anything out on their own. It's sad really. They are clueless and the consumer is getting shafted.

If a cat is dead, typically it will do more than just hurt power at high rpm's. When they go, they usually go pretty noticably. The car will idle rough, the cat will physically glow and you'd probably smell a burning smell. The one's I've had fail all did this. There was absolutely no question about it.

zoom44

wow i finally have something to disagree with fred about!!:o

there have been many cats going south on 8s here and abroad which dont show the "usual" cat symptoms you describe. there are 2 cels in our cats one before the sensor and one after. when the back one starts to deteriorate or become clogged with small bits of the front it can and does cause intermittent lose of power at higher rpms. without throwing a CEL even. as the damage becomes worse it starts to display more of the symptoms you describe. but at first it seems normal until you get to the higher rpms when the restriction to the flow becomes more noticeable. some have noted "puffs of white smoke" and then normal operation for a awhile again. this i believe is the broken down catalyst temporarily being "burped" out.

read the thread in the ukclub i linked to and another there titled something like " a new cat = a new car"

Razz1

And if the Cat is good, which i doubt, you can check the coils.

rotarygod

I still highly doubt this is a cat issue. I know for an absolute fact that Richard's car doesn't have cat issues. It's the auxillary ports on his car and this sure sounds like the same thing.

I find it disturbing that anyone is having cat issues on the RX-8. If cats are failing at all on a car this young, the cats have a manufacturing defect. Personally I feel that you should only use a cat on a rotary 1 day a year anyways. That's the oinly time you really need one. I've had my RX-7 cat glowing orange on several occasions from running it too lean. I've gotten it so hot that the split air pipe from the cat to the emissions control system has caught on fire. I proceeded to extinguish it and the red glowing cat with the water hose. Cat still works fine. I've flooded the car several times. Cat still works fine. They are actually quite tough and do not get bothered by simply flooding the car once or overheating it once. I've seen several people on the forum suspect the cat might be bad because the car may have been flooded once. So what? That won't hurt it. Mazda must have had a very bad batch of cats get installed in these cars because even older rotaries didn't have reported cat failures so early in life or from such simple things as flooding. When they did go they did so impressively. I think that Mazda and too many RX-8 owners have just become so dependent on diagnostics from the ecu that they soley trust these results. Too bad the diagnostics don't tell you everything that is wrong. The car may tell you the cat is bad because it gets a slightly off reading and then proceeds to change the way the car runs. The cat might actually work just fine and still be capable of doing it's job but the ecu is responsible for making the car run bad. I feel that technology has gotten in the way too much on this car and that too many people are relying on it to tell them everything is fine. As much as diagnostics tell you about this car and how much control the ecu has over the car, there are still things it doesn't do properly. There are only 2 possibilities in regards to the cat right now. 1: The cats are defective from factory. 2: The ecu is messing things up due to the readings it is seeing. We all know the ecu doesn't do anything weird!

Charles R. Hill

iTrader: (7)

This is exactly the same problem I have experienced since I had my N flash done. All along I thought it was the nitrous backfire I experienced that started the problem. This thread is telling me that I am not nuts. Thanks, everyone. I noticed that my noise comes at about 7K rpm's and is much louder when I use my Rotary Extreme intake and, especially, my nitrous. The nitrous used to cut a full second off my e.t. but now it only cuts about .3s off. I used to feel a bit of a punch at 4K, then another one REAL HARD at 6,250 when the last ports opened up. Please keep me posted on any progress and I will do the same. It is this problem that is keeping me from hitting easy high 12's with the nitrous.

CRH

Mr M

Cats on RX8s can melt and reduce performance, with no other noticable symptoms. Not so much now with the new flashes (running leaner=less fuel at cold start/less flooding).

The APV does not really need DTCs, it is easy to test and very noticeable if it is not working (the car is a slug and bucks and jerks under heavy throttle). The easiest way to test it is to disconnect it and go for a drive. If the car performs worse then you know it was working before you disconnected it. You can also test it with a voltmeter while revving the engine. When it is being opened the PCM feeds 12V to one side (wire) of the APV motor, when it is being closed the PCM feeds power to the other wire (the wires are the Blue/Red and Green/Black ones). Simple.

Also, make sure you (the original poster of this thread) have the latest PCM flash. There was also a perfomance problem that was fixed with the M flash.

zoom44

fred i agree cat issues ar edisturbing. but many of the cat problems were not discovered by the electronics but by reading these symptoms and having the cat checked physically.

zoom44

oh and i dont think richards problem is his cat either

rotarygod

Maybe the initial conservative tuning that was done to protect the cats was actually done to protect substandard weak cats?

Charles R. Hill

iTrader: (7)

What if you have no cat and still experience the problem?

I'll be checking the APV motor and circuit on Friday.

CRH

Charles R. Hill

iTrader: (7)

I just got done reading through the TSB regarding the loss of power/"knocking" sound above 6,000+/- rpm's. In the TSB Mazda explains that the noise is caused by improper/low MOP volume leading to a loss in rotor-to-housing seal. If the noise/loss of power that I am experiencing is the same as several others on this post I think I can explain how this works. If I am wrong I expect to be corrected by someone with more knowledge than I. Here goes;

The metering oil pump supplies the oil that seals the apex and side seals in the rotor housings. When the oil volume delivered in the housings is of insufficient level to ensure proper sealing the dynamic combustion pressure will bleed past the seals and rotors. Since rotary engines have no valves to close off the combustion chamber, this dynamic pressure is bled back through the intake manifold and results in severe reversion pulses that sound like rumbling or knocking that gets worse with rpm's and results in a loss of power. Any mods that raise the dynamic housing pressures or otherwise increase airflow through the engine will cause this problem to magnify. Intakes and exhaust systems will affect this issue and, to a much greater degree, so will turbo and nitrous systems. Apparently this MOP volume problem was inherent in the earlier production models that were delivered with the L flash. The M flash was supposed to cure this problem, along with several other issues reported to Mazda, but this may not be the case.

In my particular case, the M flash worked quite well with nitrous oxide and I was able to pull off 13.3's in the 1/4 mile with no traction in first and second gears and with relative ease. Once I had the N flash done I measured easy 13.7's w/o nitrous and expected to be able to tear off similarly easy 12.8-12.9's based on the performance boosts measured while previously using the nitrous. Although the nitrous and N flash worked well for a few times I never had the chance to measure my times specifically and shortly thereafter I began to have issues with the N flash and nitrous.

After reading the Mazda TSB I am fairly confident of one, or both, of two things. First, neither the M nor N flashes have cured the MOP volume issue and I need to be sure to have that matter investigated. Second, since there are no "accepted modification" or MSP04 stickers on my car, the dealer has not actually installed the upgraded PCM flashes. My work order from my last visit indicates that the service was performed so the stickers may have been overlooked.

Whatever is going on I will, once again, visit my dealer and speak with them about my problem(s). As soon as I have this matter resolved once and for all I may resume my quest to run a high 12-second 1/4 mile.

CRH

Mr M

You are bang on the button with your explanation about blow-by caused by lack of apex seal lubrication/sealing.

Regarding the effectiveness of the flashes, MC try to cover as many theoretical usage situations as possible with their reprogramming, sounds like your particular situation was one that slipped through the net.

I'm not sure if I'm reading your post right, but if you are in doubt maybe you should have a technician check your PCM level with WDS? An update might just solve all of your problems.

If you really want to play with the MOP delivery rate (not recommended...) maybe the CANZOOMER PCM or whatever it is called will allow that?

Have fun!

Charles R. Hill

iTrader: (7)

Thanks, Mr M. I was confident in my understanding of the need for oil to ensure the seal/housing interface as that is explained in the TSB but what do you think about my extension of logic surrounding the idea that the blow-by will be evidenced as noise on the intake side? If you think that I am correct on that one then my performance issue may have just been defined and I can now set about a particular solution.

Here is the strange thing; I went to my dealer 2 months ago and told the service tech. that I heard about the N flash and how it was supposed to make the car more driveable. He followed the MSP04 instructions to a "T". I guess I got the re-flash because the car ran very smooth, and it still does(but they forgot the 2 stickers indicating the mod). However, the problem regarding loss of power/knocking at high rpm's was never present until AFTER I had the N flash for a while. Perhaps I have a MOP failure of some kind that was coincidental with the re-flash. Let's hope it is that simple so I can get back on track with my nitrous project. I have some people who want to have their "asses handed to them" in the parlance of the epic drama The Fast and the Furious.

CRH

TJ13b

Hey CRH, I know its been sometime since this post but im having the same issue with the knocking sound in the high RPM and lose of power. Just seeing if there was a outcome to the issue.
Cheers

TJ