I’ve been chasing and throwing parts at the s6 left and right trying to find this misfire. It’s random/all cylinders. As soon as the car comes to a stop it starts shaking and misfiring bad. But as soon as I’m rolling and has any rpm above idle it has Zero misfires. It is happening both in neutral/park and in drive, however it seems to be slightly worse (most times) in drive. Any advice or people who have been in the same situation help is appreciated!
carbon buildup?
I had a leaky injector o ring about 200 miles ago and did a carbon clean while I was in there
About the only thing I feel as if I didn’t replace it the pcv. The car seems like it has a vacuum leak somewhere, but cannot find it. When i had a bad PCV valve I had more than normal oil cap suction. Now, I have zero to nearly zero vacuum on the oil cap. Could a bad PCV cause these symptoms?
If you find (plenty of) oil in the upper intake manifold, yes. Tilt it and see if any oil comes out at the intakes if they are tilted down. I would expect misfires rough sound at startup idle.
Last night I popped the pcv hose off and nothing changed then I blocked the pcv with a flat piece of metal and it idled perfectly smooth while I had it there so I went ahead and ordered a new one.
The PVC system and the diaphragm in the oil separator can fail. That causes a big disturbance.
Let us know if that sorted it out.
I threw a rubber glove over the fitting on the pcv and hose and started it and let it run for a few minutes with no misfires so I’m hoping that’s what it ended up being. I’ll know for sure Wednesday when the new one is here
I installed the new pcv yesterday, and unfortunately it ran the same as before. So I checked once again with blocking PCV valve and it ran completely smooth. So I’m now thinking that the old PCV might not have been the problem and there is something else causing this. But I have no clue where to look now.
Can you read the lambda value with a VCDS, for example? Pressure differential between intake and the headers (or where the pcv intake is located): Wild guess, not based on experience, clogged cats restricting exhaust airflow.
Can you post a picture showing where exactly you are blocking the pcv?
And did you do a smoke test on the entire intake system?
Considering you are unplugging the PCV at the PCV valve only, I see 3 possibilities:
- The PCV pipe going to both valve covers is leaking somewhere
- The PCV itself is leaking
- The oil return hose going from the PCV to the V between the heads is leaking
Also I’d say it migh be possible, that the vacuum hose going from bank 1 intake pipe to the V has a faulty valve. You can check it by unplugging it, and trying to suck and blow air through it. It should only let the air one way.