996 3.6L Multiple misfires (4-5-6) only at 1500rpm

[Brad Roberts]

This one is driving my nuts..

 

Anyone with good solid suggestions on *why this car is only misfiring on 4-5-6 and only at 1500rpm?

 

Coil packs replaced, spark plugs replaced, fuel volume good, 02's read consistent side to side, cam variation is only -1.25 and 1.15. Maf number look good compared to other 3.6 cars we've had in here. I have *another 996 on the way with the same problem, and I was called on Monday by another tech down the street from me with the EXACt same issue in yet ANOTHER car..

 

Nevermind the multiple misfires in a track car we noticed this past weekend at the POC Tribute to Lemans race!!!

 

What's going on? Is it crappy CA. gas??

 

Help :)

[Ahsai]

Did this issue start after some engine work? How are the FRAs and RKAT?

The WSM mentioned misfires at 1200-1500rpm could be due to variocam timing not fully activated. There are some tests (o2 adaptation) to verify. Maybe you can compare the actual cam angles of both banks around that rpm?

[Brad Roberts]

I'll bring up FRAs and RKAT info and report back!

 

I may need more info on the 02 adaptation tests!

 

I'll also bring up cam timing on both banks and data log them from 1200-1700

 

I *should have looked at the FRAs and RKAT and didn't :(

 

Thanks for the leads!! *Sometimes we just need a clear head to think this through :)

 

 

Did this issue start after some engine work?

 

Negative Ghost rider :) 58k mi. C4 convertable. Clean car.

Edited May 21, 2015 by Brad Roberts

[Ahsai]

PM sent.

[Richard Hamilton]

What were the codes? P0300, P0304, P0305, P0306? Any others? If no others, my money would be a Variocam solenoid.