Intermittent stumble under WOT past 5k RPM's
 

I have an 03 G35 Sedan 6MT and after installing a JWT Popcharger, my car has an intermittent stumble under heavy throttle whenever I go past 5K RPM's. I recently had my drivers side camshaft position sensor replaced as I got a P0345 code, but that didn't fix it. My mechanic test drove it and ran to redline from 1st to 3rd and he could not recreate it, but on my way home, it happened two times when I went WOT. I've tried researching it but I'm still at a loss as to what it could be :/. Anyone have any ideas?

Are you sure you aren't hitting the RPM limiter? I should kick in around 6200 RPM.

I doubt it because this feels like the car heavily jerks back and then goes smooth again for a second. I dont think a rev limiter would make the car jerk back like that.

Sounds like it could be the limiter. When mine kicks in the car bucks like a bronco, the revs come down and its smooth again but if you stay on the throttle it will do it again. If you are redlining it that often there are two things to do:

1. Don't redline it
2. Get an Osiris tune with the rev limiter set higher

Hmmmm.....I'll have to look closely at my RPM's next time to make sure it's actually going past 6000. I could of sworn I've gone past 6.5k before and it didn't lurch like it does now.

My question would be, why are you revving it so high? Shift a little earlier and put less strain on the engine.

It's starting to get warm here in New England and some days I feel like a bit of spirited driving, but knowing that my car is going to lurch like this (if it isnt the rev limiter) kills the mood :/.

If you're going to drive it like that you should really get a tune... not healthy for the engine if you haven't

I'd like to, but before I do that I need to figure out why its doing this stumble above 5k all of a sudden.

Have you reset the ECU since installing the pop? If not that might help the computer adjust for your increased air flow and get rid of the hesitation. Also make sure everything's buttoned up in the intake tract and that the MAF is clean.

There is also a reset sequence to recalibrate the MAF. I am not sure what the programming sequence is though, someone else did it on my car.

When my mechanic replaced my camshaft sensor he had the battery off long enough for my radio settings to reset which I'm guessing is 30 minutes or so. Is that long enough for the ECU to reset completely?