[tequila318325]

Hello, maybe someone may know what could cause this? The revs slightly drop on only cold starts, when the engine is warm everything is ok. E92 325i. Adding a link to the video : https://www.dropbox.com/scl/fi/gggbi...=v1rh6gj6&dl=0

[gavan_davis]

I had this problem a few months ago with my E91 328xi. Turned out to be a vacuum leak in one of the lines and the valve cover. Not entirely sure which line, as the small dealership I bought it from did a smoke test and just fixed it without many specifics. The previous owner had somebody “repair” the cracked valve cover with a bead of silicone…not how that works.

It had the same issue as in your video, cold starts would rev between 400 and about 1600, but would idle more normally the closer it got to operating temperature. Not exactly sure how much a smoke test costs since the dealer fixed everything free of charge, but that could be a good place to start.

[tequila318325]

Originally Posted by gavan_davis

I had this problem a few months ago with my E91 328xi. Turned out to be a vacuum leak in one of the lines and the valve cover. Not entirely sure which line, as the small dealership I bought it from did a smoke test and just fixed it without many specifics. The previous owner had somebody “repair” the cracked valve cover with a bead of silicone…not how that works.

It had the same issue as in your video, cold starts would rev between 400 and about 1600, but would idle more normally the closer it got to operating temperature. Not exactly sure how much a smoke test costs since the dealer fixed everything free of charge, but that could be a good place to start.

My car literally had a valve cover replaced 1 week ago
After it got replaced everything seemed fine for a few days and then this started to happen.

[gavan_davis]

That’s really unfortunate if it is the cover or gasket. Can you see any oil around the bottom of the cover?

[tequila318325]

Originally Posted by gavan_davis

That’s really unfortunate if it is the cover or gasket. Can you see any oil around the bottom of the cover?

Fortunately no, it looks bone dry.

[gavan_davis]

That’s a good sign but I guess since it was only done a week ago it may not be leaking yet depending on how much you’ve driven, if that is the problem. I’m not 100% sure but a dirty MAF might also contribute to this? Before taking my car back to who I bought it from, I sprayed the MAF with CRC MAF cleaner (use that specific product if you choose to clean the MAF), but it didn’t help me since there was a vacuum leak. There’s a few DIY smoke tests on YouTube using a cigar and transfer pump, but I don’t personally know anyone who’s actually ever done it that way, so I can’t entirely recommend that.

[TheMidnightNarwhal]

Originally Posted by tequila318325

My car literally had a valve cover replaced 1 week ago
After it got replaced everything seemed fine for a few days and then this started to happen.

Then it's probably one of the vac lines.