The Acceleration Stutter - Pulling my hair out.
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The Acceleration Stutter - Pulling my hair out.
I've had the stutter show up on my '11 S All4 with 114k on it. It's all stock. PCV and Valve Cover replaced at 104k. Replaced plugs and all 4 coils, ran a few cans of BG44k through the tank. Noticed the spark plugs with 10k on them had a bit of black crusty stuff on them, maybe a tinge of white to them. All four of the cylinder heads viewed through the spark plug hole appeared black and somewhat crusty looking. No codes show up except for misfire codes, but they haven't come back since clearing. Took it by my BMW repair shop and they hooked up the Autologic to it, no hidden codes and we did a quick check on the HPFP, at least during idle and light acceleration it wasn't showing any issues. We looked at the Expected/Actual real time values and they stayed very consistent. There was another screen in regards to the HPFP that showed two MPa values (one 6.5 MPa and another .5455 MPa) but I don't remember what it was reading and my screenshot of the autlogic unit has sun glare covering up the descriptions.
So, next step was to do a smoke test, and that showed no leaks anywhere, which was actually surprising to me, but during the test I took off the three intake pipes closest to the throttle body and noticed that there was enough oil pooled in them to coat my fingers. Also noticed that there was a reddish orange gunk, that looked like gasket material in there. It was in very small pieces, finely shredded maybe? I guess it would have to be in order to go all the way through the intercooler. So I cleaned all that up, and then checked the oil (which had been recently changed by a local shop)... and it was overfilled by almost 2/3 - 1 quart. Pulled some out to get the oil to a normal level, thinking that excess oil was running through PCV system and causing the buildup, and thereby possibly the misfiring since oil was essentially getting shoved into the cylinders during heavy boosts?
So I drove it another thirty miles pushing it hard to try to burn up any excess oil, but while it seems that the stutters are less pronounced they are still happening.
Wondering if anyone has any idea what gasket or sealant compound might be going through the oil system? My thoughts were the PCV, but it's only 10k old, or the blow off valve possibly? Or any ideas on what's happening overall?
The whole problem is frustrating due to a lack of codes to work off of, but hopefully, I'm on the right path.
So, next step was to do a smoke test, and that showed no leaks anywhere, which was actually surprising to me, but during the test I took off the three intake pipes closest to the throttle body and noticed that there was enough oil pooled in them to coat my fingers. Also noticed that there was a reddish orange gunk, that looked like gasket material in there. It was in very small pieces, finely shredded maybe? I guess it would have to be in order to go all the way through the intercooler. So I cleaned all that up, and then checked the oil (which had been recently changed by a local shop)... and it was overfilled by almost 2/3 - 1 quart. Pulled some out to get the oil to a normal level, thinking that excess oil was running through PCV system and causing the buildup, and thereby possibly the misfiring since oil was essentially getting shoved into the cylinders during heavy boosts?
So I drove it another thirty miles pushing it hard to try to burn up any excess oil, but while it seems that the stutters are less pronounced they are still happening.
Wondering if anyone has any idea what gasket or sealant compound might be going through the oil system? My thoughts were the PCV, but it's only 10k old, or the blow off valve possibly? Or any ideas on what's happening overall?
The whole problem is frustrating due to a lack of codes to work off of, but hopefully, I'm on the right path.