EPC Light and Harsh Vibrations after Hard Throttle with Low Traction

[DogParty]

Long time lurker. So 2017 Golf AT with 40k with APR Stage 1 (only last 4-5k). Plugs replaced/gapped right before the tune, along with filters. Oil every 5k. Proper octane fuel, although it did get a good bit of injector cleaner on this tank, probably more than it called for but nothing crazy.

Last night, I hammered it coming out of a turn and it was a little wet out so I wasn't getting much traction, revs shooting up to 6-7k and back down and back up without much acceleration. When the revs shot up the last time, the engine made a weird bogging noise and EPC light came on. Car started vibrating like crazy (maybe a cylinder not firing??) and I slowed down to a stop. I turned off and on immediately and everything was okay. Lots of hard throttle today with no issue.

No scan tool to read any codes. No check engine light or anything, just the EPC which reset after I restarted the car. Any ideas??

Also, is it bad to stay on the throttle when I don't have traction? Like when the revs are shooting up to almost red line and back down a few times quickly from loss of traction. And I swear I've seen the needle go all the way to 8k at some point a while back from doing this. Is that just the gauge not reading properly or is the engine actually revving way too high?

Thanks for your input!

 

[MeltedSolid]

Sparky has had this issue before, low traction coming out of a specific uphill corner and wheel spinning like crazy, getting an EPC light, then it going away like it never happened. I don't remember what the solution was, or if there even was a solution.

Also, chances are you didn't see the tachometer go to 8k, just to the ~7k fuel cut (unless something else went wrong...). If it did go up that high it would probably put you into limp mode like you experienced, but you would also potentially have some other major issues.

 

[jimlloyd40]

It most likely over revved which triggered the EPC light. And yes it can be bad.

 

[Sparky589]

Hrm I've certainly had this issue in the past, but I will say that I never observed an over-rev situation (nothing above 7k) whenever the EPC light was on. Running codes indicated misfires, usually in cylinder three and two if memory serves.

Ultimately the issue was so infrequent, and so easily remedied that I never spent much time chasing it. I've literally never had it happen to me once I started running Is38, so part of me wonders if there is something tuning related going on here. At the same time, Is38 has less power down low, so breaking the wheels isn't as frequent of an occurrence as it was on my Is20 tune. Of course this is helped by the fact that at this point my car has virtually everything on it that could possibly aid in granting additional mechanical grip. Furthermore this issue never occurred to me on my Stage 1, and was exclusive to my tenure with Is20.

Are you running stock tires and suspension? The only constant I had was a loss of traction, and even that wasn't a grantee of triggering the misfire. I'd certainly recommend a code reader at the very least (everyone should really have one), but also a quality dogbone insert if you haven't got around to installing one yet.

 

[tigeo]

Limp mode. Need to read your codes but the ECU didn't like something is all.

 

[DogParty]

Thanks for the replies everyone! It did it a few more times in the past month, but the only common denominator was high revving. Restarting the car cleared it all up every time. Still stock suspension and have very crappy snow tires on now (still way better in the snow than the all seasons though).

Codes read were P0302, 3, and 4. Misfires in cylinders 2, 3, and 4. They were listed as "pending" on the cheapo scan tool. Hopefully that means it was just those few instances and not occurring normally.

I got new coils and plugs so we'll change those out if it keeps doing it. Could it be related to the cold/winter weather?

 

[DogParty]

I should add that it was only the EPC light the first three times, the fourth and last time, both EPC and blinking CEL. Again, cleared immediately after a restart of the car. I don't think you can get codes from just the EPC light, right?

 

[Sparky589]

The car's ECU should log codes after the fact, and yes, anything that triggers any dash light (outside not plugging your seatbelt in) will come with a logged code.

 

[jimlloyd40]

I should add that it was only the EPC light the first three times, the fourth and last time, both EPC and blinking CEL. Again, cleared immediately after a restart of the car. I don't think you can get codes from just the EPC light, right?

If you scan your car after getting an EPC light you will definitely have codes set.