Misfires, slightly glowing cat, and a few questions. I'm out of ideas.
02-25-2014, 07:37 PM
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Misfires, slightly glowing cat, and a few questions. I'm out of ideas.
Hey guys, been a while....
'06 Rx8 Shinka MT I bought in the middle of '08, just over 60,000 miles, original engine, premix every fill-up, religious oil changes every 3,000 with classic dino-oil. I just paid it off last month.
In December of last year, I had a blinking CEL indicating a misfire and quickly did a tune-up. New coils, plugs, wires, starter, battery. Car ran absolutely great. I would wager that it ran better than when I bought it.
This past weekend the car started acting funny, another blinking CEL, which eventually stayed on. I yanked the battery cable, cleaned all the connectors for the sensors I could find (MAF, TPS, ESS, etc.) as well as many of the sensors themselves.
I didn't think to have the code scanned before yanking the battery, and now the I can't get the CEL to come back. Regardless, the car is running like crap.
My observations:
- Car starts and idles just fine. Purrs like a kitten. Considering the temperature right now in Michigan, the starting performance is spectacular. I actually attribute this to the new starter and battery.
- 1st gear revs up fine to the redline. Starting with 2nd gear, it starts to stumble if I mat the throttle. Each successive gear is worse.
- When the car starts stumbling, the exhaust tone changes, almost sounds like it's running really rich. The last time I had any vehicle behave like this, it was a mid 80's Grand Prix with a carburetor. The typical rotary "braaaaap" would then sound like a deep "bwa-a-a-a-a-a-a-a-a-aa-a" with some slight vibrations. If I slowly roll into the throttle as the revs build, I can keep it from "bwa-a-a-aa-a-ing", but what's the fun in that?
- Freeway cruising in 4th or so, if I mat the throttle (bwa-a-a-a-a-a-a-aa-), it will accelerate far more slowly than if I were to ease into the throttle. Again, behaves like it's running rich.
- I don't really have enough evidence to support this, but the condition seems worse with more fuel in the tank. This morning, with less than a quarter of a tank, I didn't seem to have any issues. I filled up at noon, and the car has been crap since.
- After some spirited driving (when the car cooperates), I can see a faint red glow from the catalytic converter. I know these cars have a hotter than usual exhaust, but should I be seeing any red at all? By spirited driving, I mean a couple miles of freeway with the engine up to temperature, then two consecutive redlines through 1st, 2nd, and almost into 3rd for the last half mile of my commute, and then peeking under the car once I'm home. Keep in mind, ambient temperature is about 20* F, so it should cool really quickly, and my driveway twists'n'turns for 1/8 of a mile. Plenty of time to cool.
- When the car cooperates, it has all the power it ever did (especially after the tune-up in December). I haven't had a compression test done, but I don't suspect any compression loss.
So, whaddya guys think?
- Fuel pump?
- Catalytic converter? (This would make the most sense, since I just passed the 8 year federal warranty....*rollseyes*)
- Something else?
Thanks guys!
'06 Rx8 Shinka MT I bought in the middle of '08, just over 60,000 miles, original engine, premix every fill-up, religious oil changes every 3,000 with classic dino-oil. I just paid it off last month.
In December of last year, I had a blinking CEL indicating a misfire and quickly did a tune-up. New coils, plugs, wires, starter, battery. Car ran absolutely great. I would wager that it ran better than when I bought it.
This past weekend the car started acting funny, another blinking CEL, which eventually stayed on. I yanked the battery cable, cleaned all the connectors for the sensors I could find (MAF, TPS, ESS, etc.) as well as many of the sensors themselves.
I didn't think to have the code scanned before yanking the battery, and now the I can't get the CEL to come back. Regardless, the car is running like crap.
My observations:
- Car starts and idles just fine. Purrs like a kitten. Considering the temperature right now in Michigan, the starting performance is spectacular. I actually attribute this to the new starter and battery.
- 1st gear revs up fine to the redline. Starting with 2nd gear, it starts to stumble if I mat the throttle. Each successive gear is worse.
- When the car starts stumbling, the exhaust tone changes, almost sounds like it's running really rich. The last time I had any vehicle behave like this, it was a mid 80's Grand Prix with a carburetor. The typical rotary "braaaaap" would then sound like a deep "bwa-a-a-a-a-a-a-a-a-aa-a" with some slight vibrations. If I slowly roll into the throttle as the revs build, I can keep it from "bwa-a-a-aa-a-ing", but what's the fun in that?
- Freeway cruising in 4th or so, if I mat the throttle (bwa-a-a-a-a-a-a-aa-), it will accelerate far more slowly than if I were to ease into the throttle. Again, behaves like it's running rich.
- I don't really have enough evidence to support this, but the condition seems worse with more fuel in the tank. This morning, with less than a quarter of a tank, I didn't seem to have any issues. I filled up at noon, and the car has been crap since.
- After some spirited driving (when the car cooperates), I can see a faint red glow from the catalytic converter. I know these cars have a hotter than usual exhaust, but should I be seeing any red at all? By spirited driving, I mean a couple miles of freeway with the engine up to temperature, then two consecutive redlines through 1st, 2nd, and almost into 3rd for the last half mile of my commute, and then peeking under the car once I'm home. Keep in mind, ambient temperature is about 20* F, so it should cool really quickly, and my driveway twists'n'turns for 1/8 of a mile. Plenty of time to cool.
- When the car cooperates, it has all the power it ever did (especially after the tune-up in December). I haven't had a compression test done, but I don't suspect any compression loss.
So, whaddya guys think?
- Fuel pump?
- Catalytic converter? (This would make the most sense, since I just passed the 8 year federal warranty....*rollseyes*)
- Something else?
Thanks guys!
02-25-2014, 09:02 PM
#2
You gonna eat that?
iTrader: (1)
Blinking CEL is misfires, misfires kill cats, CEL staying on could be bad cat.
That's how mine went, new ignition & midpipe worked.
Check the cat. Disconnecting the battery cleared the CEL, & it may not come back for a while, my experience also.
If the cat is bad you could be damaging your engine in the meantime.
That's how mine went, new ignition & midpipe worked.
Check the cat. Disconnecting the battery cleared the CEL, & it may not come back for a while, my experience also.
If the cat is bad you could be damaging your engine in the meantime.
02-26-2014, 09:49 AM
#4
"I wanna go fast!"
Is it noticeably worse around 4-5K rpms and then 6-9K? I have the same issues with that "stumbling but only around that rev range. And i am pretty sure it is running really rich as it drives better after i pull battery and reset afr. Then it "learns" and it starts to bog down. Funny thing is... this only happened after i cleaned the air filter.
Anyways, i replaced the MAF like suggested and it helped fix the problem. Original around 6K rpms it would hit a wall and struggle before opening back up. It doesnt do that anymore but still doesnt smoothly rev through the whole range.
Im gonna run some more seafoam, check plugs again, and then if im not convinced im going to check the SSV.
Also, i gutted my cat as it was clogged. Helped for a little while. Check ur cat and if it isnt an issue then this sounds most definitely like an ignition problem. Did you find any oil backfeed in ur intake? This could cause a stuck SSV after a while.
Anyways, i replaced the MAF like suggested and it helped fix the problem. Original around 6K rpms it would hit a wall and struggle before opening back up. It doesnt do that anymore but still doesnt smoothly rev through the whole range.
Im gonna run some more seafoam, check plugs again, and then if im not convinced im going to check the SSV.
Also, i gutted my cat as it was clogged. Helped for a little while. Check ur cat and if it isnt an issue then this sounds most definitely like an ignition problem. Did you find any oil backfeed in ur intake? This could cause a stuck SSV after a while.
02-26-2014, 05:47 PM
#6
You gonna eat that?
iTrader: (1)
+1!
That is what a bad cat does.
It may be the most common cause of engine failure.
Glowing cat & stumbling at WOT are classic symptoms. You can gut it if you have to drive it.
That is what a bad cat does.
It may be the most common cause of engine failure.
Glowing cat & stumbling at WOT are classic symptoms. You can gut it if you have to drive it.
03-04-2014, 12:47 PM
#7
Rotary Evolution
a glowing cat does not automatically mean it is faulty...
misfires due to failing ignition cause unburnt fuel to enter the exhaust, as it is burned in the exhaust and consumed by the cat the cat heats up warmer than usual. of course running it prolonged like this will eventually kill the cat anyways, which is probably why people immediately put the blame on it.
severely low compression on a single rotor or a failing seal internally will also mimic a faulty ignition and dump excess unburnt fuel into the exhaust. i guess i'm just tired of everyone saying the cat is junk just because 1 symptom pops up, because aftermarket cats aren't as efficient, a new OEM one is $$ and removing it isn't for everyone.
the engine only has 1 fuel trim O2 sensor, so any effects from a single rotor failing in doing its job can result in the above.
there's 3 things you can do:
monitor the ignition with a timing light on each of the 4 leads to see if there is any drop out of ignition firing sequences indicating a misfire due to ignition
inspect the catalyst physically by dropping it down and checking the core for fractures/clogging with a light
compression test the engine to see if the misfires are due to compression/internal engine issues(to do this accurately with the MSP engine you need a digital compression tester)
other less frequent issues can arise in the fuel system, like a cracked pump housing causing low fuel pressure or a stalling/seizing fuel pump.
misfires due to failing ignition cause unburnt fuel to enter the exhaust, as it is burned in the exhaust and consumed by the cat the cat heats up warmer than usual. of course running it prolonged like this will eventually kill the cat anyways, which is probably why people immediately put the blame on it.
severely low compression on a single rotor or a failing seal internally will also mimic a faulty ignition and dump excess unburnt fuel into the exhaust. i guess i'm just tired of everyone saying the cat is junk just because 1 symptom pops up, because aftermarket cats aren't as efficient, a new OEM one is $$ and removing it isn't for everyone.
the engine only has 1 fuel trim O2 sensor, so any effects from a single rotor failing in doing its job can result in the above.
there's 3 things you can do:
monitor the ignition with a timing light on each of the 4 leads to see if there is any drop out of ignition firing sequences indicating a misfire due to ignition
inspect the catalyst physically by dropping it down and checking the core for fractures/clogging with a light
compression test the engine to see if the misfires are due to compression/internal engine issues(to do this accurately with the MSP engine you need a digital compression tester)
other less frequent issues can arise in the fuel system, like a cracked pump housing causing low fuel pressure or a stalling/seizing fuel pump.
Last edited by Karack; 03-04-2014 at 12:59 PM.
03-04-2014, 01:15 PM
#8
You gonna eat that?
iTrader: (1)
Still waiting on my midpipe. In the mean-time, I bought a wifi elm327 unit and this thing is just incredible....far too much information for me to know what to do with.
However, I do have wildly fluctuating STFTs, all positive, up to 15%. This means it's adding fuel for a perceived lean condition. I read that around 25% triggers a CEL.
This thing also says my cat is sitting about 1100* at idle, and almost 1700* at cruising speed.
What would be some useful things to monitor with this? Does any of the above help pinpoint the issue? Bad cat, bad upstream o2?
However, I do have wildly fluctuating STFTs, all positive, up to 15%. This means it's adding fuel for a perceived lean condition. I read that around 25% triggers a CEL.
This thing also says my cat is sitting about 1100* at idle, and almost 1700* at cruising speed.
What would be some useful things to monitor with this? Does any of the above help pinpoint the issue? Bad cat, bad upstream o2?
03-05-2014, 04:45 PM
#9
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You can do way better on that price. A new reman from Mazmart is $3,300 + shipping + $1,000 core charge which gets refunded once your old engine gets to them. If you have them add the various Remedy produces to the engine, it's $3,800.
For $2,500-$3,500 range, you could have the engine rebuild at Rotary Resurrection, or more if you expand that to BHR, or Pettit.
For $2,500-$3,500 range, you could have the engine rebuild at Rotary Resurrection, or more if you expand that to BHR, or Pettit.
03-05-2014, 07:58 PM
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To be fair, Mazmart's engines are Mazda remans too. But if you buy a reman from a dealer they will mark it up far more and tell you to go shove it if you find out that the engine is dead on arrival. Buy it from Mazmart and not only are you far less likely to have a DOA engine (I believe they do some sort of testing on it, but I don't know the details), but if there IS a problem, Paul will work with you to figure out a solution that everyone is ok with. He doesn't abandon customers.
I would feel really concerned about buying from a dealer, I wouldn't buying from Mazmart, even if "you get the same thing".
If you want to ensure exactly the kind of quality you want inside the engine, go with Rotary Resurrection for a quality rebuild that is also affordable, or BHR or Pettit if you want to pay top dollar for top quality. Pineapple Racing is also apparently a good one, though not much about them on here. A few engines that seem to be pretty good.
I would feel really concerned about buying from a dealer, I wouldn't buying from Mazmart, even if "you get the same thing".
If you want to ensure exactly the kind of quality you want inside the engine, go with Rotary Resurrection for a quality rebuild that is also affordable, or BHR or Pettit if you want to pay top dollar for top quality. Pineapple Racing is also apparently a good one, though not much about them on here. A few engines that seem to be pretty good.
03-06-2014, 12:07 PM
#11
Rotary Evolution
also a cheaper alternative would be to find a used engine from a totalled car(accident only) which usually ensures the car was in driving condition when the engine was put to rest. but second hand engines aren't the best alternative, perhaps one to get by temporarily while leaving you a second core engine to have rebuilt properly and to have as a backup.
but with compression that low on a single face i'm betting at least 1 iron is damaged(broken side seal), perhaps the rotor and housing(s) as well.
but with compression that low on a single face i'm betting at least 1 iron is damaged(broken side seal), perhaps the rotor and housing(s) as well.
Last edited by Karack; 03-06-2014 at 12:10 PM.
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