Mis-Fire diagnosis/issues
 

OK, I need the wisdom of the forum to help me understand or uncover the issue of the random mis-fire codes.

At Road America, first time racing the car, I had the P0300, 0301, 0303 codes for random, cyl 1, and cyl3 mis fire codes. The car was on original plugs/coils, so we put all new plugs/coils after that event, and at Gingerman, car never seemed to mis-fire, but it's also a shorter track that didn't really get the car deep into 5th gear, where it routinely mis fired at RA. It was very slight so didn't hamper performance that much, and could be driven through.

Fast forward to today, at NCM for the first time, and immediately starts mis-firing, as there are some high speed sections. However, this time, is gives P0300, and 0200 for random and Cyl 2 mis-fires, and they could be felt, massively even at lower speeds. Also, while the CEL is flashing, the TC light also comes on (the one that is off when the Pedal dance mode is engaged)….it was so bad I thought it was fuel starving, so pitted, put more gas in, went back out, and same thing happened once back up to speed.

So besides burning up another coil in such a short time, what else could cause mis-fires like this?

I have a ACT street-lite flywheel, Fluidamper harmonic damper, Antigravity lithium battery....trying to think of anything else that could possibly affect crank position sensors or ignition. I have vents in the hood. Car makes 200 WHP on E85.

Could the combination of the LWFW, plus the Fluidamper harmonic damper (which is OE size but 1lb heavier) be causing crank position sensor issues at high RPM?

Do these cars just go through coils this much? The car has literally been run for 11-12 sessions (20 min or less) on track since the all new coils/plugs.

Thanks for the input in advance!

It may not be the heat whilst in motion but when at rest. Heat soak is a helluva thing. Just how coils can die, so can sensors. What’s your cool down lap look like and how long do you run the fans after a session?

Check you direct injection seals. That is a pretty well documented issue on these cars.

I had a coil go bad midway through Saturday at NCM after having paid for the whole weekend :(:mad0260:

I don't have fans running after the session, but I do try to remember to pop the hood. Not to mention, both the last two times at track were in cool conditions (60 deg or less).

Thx. Sorry to hear that. I was supposed to be there Saturday as well, but a funeral delayed me until Sunday.

My local track has a long stretch of 5th gear. I have a 2013 BRZ, still on original plugs and coils. Never had a coil fail yet. I must be stupid lucky, maybe it cause i still have the OEM overpipe?
Maybe time to add the outside vents on your hood to help with temps?
(I know you said it was cold air temps)


I would be curious on the flywheel, I know I have head of them causing misfire issues on other applications, but usually when paired with a lighter crank pully.

I have the heavier "street-lite" version, and the Fluidampr harmonic damper is 1lb heavier than stock, but in use because it's fluid and not bonded, it actually has an effective weight of 1lb less, however, still much heavier with better vibration handling than stock, but still, I think both would contribute to slightly different crankshaft torsion.

I'm thinking about testing the OEM damper along with the Exedy LWFW which is another 1lb heavier than the ACT version, to see if that gets rid of the "phantom" random misfire code.

That said, the car had some real misfiring going on, along with P0302, so something in the ignition system def. wasn't working properly, which leads me to think that in fact Cyl 2 coil is dead again. I noticed a big drop-off in fuel economy this weekend, which coincides with mis-firing. At Gingerman it was fine, and fuel economy was really good, and no mis-fires.

Not sure if this helps, but my street only driven car cooked a cyl 1 coil once during a really hot day. The code went away and didn't feel like it was missing so i kept driving it. It got to the point a month later where if I went above 6k rpm it would trip the code. Eventually I got a notable miss when transitioning from half to full throttle at about 3-4.5k. I did spark plugs, didn't help. I did DI seals, helped a little with 93 but the lack of fuel presented itself still on e85. Finally I replaced the entire set of DI and sure enough the car ran perfect. I guess X amount of misfires in a cylinder can fry the injector given that the direct injectors are in the hot zones so to speak.

Sorry for wall of text. Hope it helps.

Edit: a good way to confirm this would be to log AFR, fuel trims, and turn on the cylinder misfire channels if using Ecutek.

Thx. Yeah, I haven't had a chance to download all my data, which I can do through my AIM MXM/Ecutek. I'm running only E85, on an E85 only tune, as it's a race car. I don't have the luxury of 93, as I need all the power I can get. I'm going to replace the Cyl 2 coil, and if it doesn't fix it then I'll start looking at injectors. But I've literally driven the car at 3 races, that's it.

Ran like a champ at Gingerman, but there was only 1 place on the track that I even got into 5th gear, so not as much chance to expose any ongoing misfire there, so it still could have been there, just not exposed like at Road America and NCM.

Will run some E85 injector cleaner through the system as well, to see if that helps as well.

I had one of these codes over the summer, and one of the direct injectors was the culprit.

If you do end up eventually replacing the injectors be sure to match the numbers of the new ones to the ones you have in the car.

I have a 8 pound aluminum flywheel on my track car and no misfire issues. I would look elsewhere.

Do you have a datalog and video?

Well, I finally confirmed something. It seems a lot of information out there says the 13-14 had the "old" wiring harness/coils, and the new one is in '15. Well, I have a '15 and thought I was good, but turns out that the old system was used about halfway through '15, and I have the old coil/harness.

Not that it's a fix-all, but I'm going to update to the new harness/coils, add more heat shielding (even though I have double sided ceramic coated Ace headers from CSG), and see how things go. I might even use the "better" coils from Cusco or another brand to help with high RPM use.

Yep, have data from my MXM setup. No video though, haven't had time to install the smarty cam yet.

get this figured out? I have a misfire on cyl 1 I haven't been able to pin down either.