Misfires / Cutouts / Hiccups at WOT - A Real Discussion

[doverosx]

1. V4.1 Intake, GFB DV+, Turbosmart Wastegate, Forge Blow off plate, NGEN Coil Packs, NGK Iridium plugs gapped by EC running phase 0/1 Pops n bangs 2015 Automatic Abarth.
2. I do not currently have a set up for datalogging. I only experience the issue on phase 1, phase 0 has no issue.
3. Spark plugs, wastegate, coilpacks and cleaning PCV system have not fixed the problem.
4. N/A
5. Yes, My breakup is as early as 4200 which is different than most peoples experiences that I have read. Sometimes the car will pull through the breakup on its own, other times I have to let off the gas and get back on it. It is not a constant problem it just randomly appears, when it happens I take note if I was pushing the car hard or not. I get it on Acceleration but the main culprit is shifting. It really likes to present itself during a WOT shift.

6. Extra Info: I recently pulled my spark plugs to replace them, this is the 4th time I have replaced the plugs on this car. This last time I noticed that the plug closest to the PCV box had its threads soaked in oil. I cleared out the spark plug tube as best as I could and hoped for the best. I did not have the issue after cleaning my spark plugs/changing them..about 3 months later, maybe 3k miles the problem has appeared again. I am going to pull them again this weekend and check out how they look. My assumption is a bad spark plug tube seal..I have not problem tackling this problem on my own, but the only company I can find that sells a full kit for the seal replacement with a valve cover gasket is a company I'd rather not risk buying anything from.

How would you describe the breakup? Is it individual hard jerks, or is it more of a "rumble/stumble" where it gets rough and loses power?

I would say its the rumble stutter. When I experience the issue its after a shift and car feels like im hitting a rev limiter and wont gain any power..Its very audible in the car too, it sounds like a fart...Forgive me for the lack of better term. It almost sounds like an audi waiting on launch control, that even stutter pattern; I will link a video with pretty much the same sound im experiencing after a shift.
https://youtu.be/_TKWT45_RLk?t=55

Like this: https://youtu.be/ZgR7eLAJJYM

[doverosx]

Great thread.

When I first went to the J&J/RAW tune (in 2015) I would get severe breakup at around 5000 rpm at WOT. That was cured by upgrading the coils to NGEN coils (which have stayed the course to date). That was a hard stumble with no CELs.

After the head work was done, with the upgraded C&B cam, I had a persistent P0300 code but that came without any kind of noticeable misfire or hesitation.. Over the last 18 months or so I've been trying to find the cause. It happened with any EC tune or stock tune; driving hard or driving gently. Over the period I took off the light weight drive pulley, I replaced the O2 sensors as they were throwing codes, chased down electrical issues because my battery kept dying and my lights worked strangely. Finally I swapped the PCV and cleaned the AOS and that made a difference. The code still appeared but it was less frequent. Last month I did an oil change and primed the multi-air with oil (long story). The code has now gone completely. I also upgraded to a FX250 clutch and lwfw at the same time, so perhaps it's related to that as well.

Currently the car is running really well, it has a slight blip around 5,000rpm. Not even a misfire really, it's like the engine just forgot to fire on one revolution and then it's off again. No CELs. I'm going to do some data logging next month to see if I can see anything odd, I have some long drives to Dallas and San Antonio to wind the car out a bit.

Log the TPS. At the top end you may be hitting limiters and getting a throttle closure. If you don’t see a large snap of the throttle, then you are most likely getting spark blowout. You might even hear a quick pop or two from the exhaust.

When I had a 5k pop that was felt 50% of the time it was the plugs. Either they were fouled from running too rich or the gaps opened up from running too hot or both. Last year around this time, I had serious gapping; all were over 0.030” after only 3000kms.