[fastboatster]

Hi all, I’m having some strange issue sometimes my engine starts to shake at idle. It happened today and was very brief, maybe a second. Felt like it was going side to side. Sometimes I get this feeling at cold idle, sometimes not. I think this has first started when one of my coils went out and I replaced it with a new one.
Seemed to have gotten better after a while. I replaced all my coils a week ago and it started to happen. Couple a days before that, I had a coolant expansion tank replaced, wonder if any coolant somehow got onto some connections.
Oh yeah, no check engine lights.
Do you know if I should reset some adaptations or maybe it’s time to check the vanos solenoids and/or their connectors?

[oVeRdOsE.]

- scan for any miss fire.
- clean the vanos solenoid, very easy. Rough idle is most of the time because of those 2.
- check ground. The easiest one to check is the one on the passenger side, next to the windshield washer white hose.

[fastboatster]

Gotcha, will do! I’m 90% certain it’s VANOS, these were replaced under warranty at 50 kmiles, and we now got almost 115 kmiles. Need to clean those.
The reason I’m this certain now is that I recall that sometimes throttle response is not as it used to be at 2,500-3000 rpm, it sometimes feels like it doesn’t pull as good

[smallseafishie]

Check your eccentric shaft sensor for oil seepage. Check your air filter and MAF. Could also have a small vacuum leak somewhere.

[fastboatster]

Originally Posted by smallseafishie

Check your eccentric shaft sensor for oil seepage. Check your air filter and MAF. Could also have a small vacuum leak somewhere.

Will check these, too, but eccentric shaft sensor seal is not leaking as of last Saturday - the valve cover was replaced 10kmiles ago.
I’ll double check the MAF, though. I should add again that these stumbles happen intermittently, I’d think that with vacuum leak it should happen all the time but idk

[fastboatster]

checked the codes - I have none, no misfires. Pulled the VANOS solenoids out, they look brand new, basically zero varnish. sprayed them with engine degreaser, reinstalled.
Anyways, I think this issue actually traces back to my bad ac pulley bearing - I get a lot more vibrations with AC on full blast. Just need to finally replace the pulley. I had the belt off on Saturday, AC pulley was a bit noisy.

[lowrydr310]

Originally Posted by fastboatster

checked the codes - I have none, no misfires. Pulled the VANOS solenoids out, they look brand new, basically zero varnish. sprayed them with engine degreaser, reinstalled.
Anyways, I think this issue actually traces back to my bad ac pulley bearing - I get a lot more vibrations with AC on full blast. Just need to finally replace the pulley. I had the belt off on Saturday, AC pulley was a bit noisy.

What did you bad AC bearing sound like? I have a vibration at idle, and I'm getting a whining noise whenever the AC compressor is on. Curious if it's the same type of noise and vibrations.

[fastboatster]

Whine, vibration and knocking

[lowrydr310]

Originally Posted by fastboatster

Whine, vibration and knocking

Knocking? What kind of knocking?

Hmm... I hear a knocking sound from the front passenger side that only happens when I stop. When I come to a stop at a red light, a few seconds later the engine RPMs drop to a low idle (~650RPM) and as soon as the RPMs drop I hear a knocking sound, about 2-3 times. I've been thinking it's my engine mounts, with the engine settling on them after I stop, but I'm now wondering if it's the AC compressor pulley.

[fastboatster]

Originally Posted by lowrydr310

Knocking? What kind of knocking?

Hmm... I hear a knocking sound from the front passenger side that only happens when I stop. When I come to a stop at a red light, a few seconds later the engine RPMs drop to a low idle (~650RPM) and as soon as the RPMs drop I hear a knocking sound, about 2-3 times. I've been thinking it's my engine mounts, with the engine settling on them after I stop, but I'm now wondering if it's the AC compressor pulley.

Yep, this is what I have. I probably should have put on a shorter serpentine belt to bypass it and see if this sound disappears, but haven't gotten around doing that. Look up e90 ac delete belt, that'll give you the belt you need and how to route it.
I spent my Saturday night doing the engine mounts, only replaced one on the driver (the harder side) because it didn't go as planned and it was getting very late at night. I'm kind of pissed it didn't fix that sound although shifting gears is marginally better.