[skinrock]

First of all, I'm well aware of the misfire sticky. I already have a new set of plugs and just bought the tools today to replace them. I am waiting till tomorrow morning to let the engine cool over night. The car has 38k on it, I have put 8k on it and at the very least it's been running those 8k with a tune/mods and the plugs haven't been changed yet.

That being said, I've been running Cobb Stage 2+FMIC Sport for the past couple weeks, pushed it a few times without any issues, but today I took off from a toll bridge and it started sputtering and felt like loss of power after 55mph or so. It would only sputter under acceleration above 55-60mph, but just driving at those speeds didn't do anything. I pulled over shortly after and read the codes, it was a misfire in 5.

Drove some more, seemed okay at first, but happened again, decided to pull into a gas station and switched to Drive map. Happened again after getting on the expressway, so I switched to Stock map (not uninstalled, just the stock like map). Seemed to be fine after that, and I cleared everything, but it looks like I did get a misfire again - but it didn't sputter or bog like the other times.

I plan on swapping coil packs during the spark plug install, just in case it is a coil, but I'm curious if these are normal symptoms. I couldn't get a definitive answer on misfires always resulting in this behavior. I'm just curious if it could be a sign of injectors, even though I'm only throwing a single code.

[Jeff@TopGearSolutions]

Need to take 1 step at a time. Either swap coil and see if it moves and or change spark plugs.

If it keeps on persisting then it may be fuel related however they are usually followed by fuel codes and if you havn't had the recalls done on the fuel hardware then its very plausible even still.

All of this is scattered in the misfire sticky I think

[GeorgiaTech335coupe]

Easiest thing to check is swap coils. To me it sounds like injectors though. Does it misfire when you 'lug' the car, WOT from high gear. That would make me think injector. An injector going bad will be much more present at higher boost than at stock boost.

[RnmEvo9]

Like Jeff said, do one thing at a time. I had misfires at high rpm's and I bought new plugs which solved my issues. I had about 55k on the original plugs.

[skinrock]

Originally Posted by Jeff@topgearsolutions

Need to take 1 step at a time. Either swap coil and see if it moves and or change spark plugs.

If it keeps on persisting then it may be fuel related however they are usually followed by fuel codes and if you havn't had the recalls done on the fuel hardware then its very plausible even still.

All of this is scattered in the misfire sticky I think

HPFP recall was done awhile ago, and they replaced some of the injectors - 1,3,4,5. Again, this isn't so much as how to debug it, I know what steps to take, I'm just sharing my experience with how the car felt and was curious if anyone else can relate.

Originally Posted by GeorgiaTech335coupe

Easiest thing to check is swap coils. To me it sounds like injectors though. Does it misfire when you 'lug' the car, WOT from high gear. That would make me think injector. An injector going bad will be much more present at higher boost than at stock boost.

Well of course I didn't go WOT after getting the misfire, I was a little nervous to really push it. It was really only slight acceleration above 55-60mph where I felt it, definitely not wot.

[skinrock]

Why wouldn't this happen. I go to remove the plug from 5 and...my extension is short by an inch to clear the cross bar. I replaced the other plugs and swapped the packs, but now I have to go buy another extension before I can finish. It started up fine and no codes at idle. The coil itself doesn't appear to look any different than the others, and the 5 plug didn't look much different.

[GeorgiaTech335coupe]

Originally Posted by skinrock

Well of course I didn't go WOT after getting the misfire, I was a little nervous to really push it. It was really only slight acceleration above 55-60mph where I felt it, definitely not wot.

? I think you misread. I'm saying you should go WOT to see if you can reproduce the misfire while lugging your car. Chances of you hurting your car are very slim.