S54 engine "stumbles" when at idle

Originally Posted by jragan

Could it be the DME adjusting to the first warm days?

I doubt it, mine used to do it in colder Boston temps. My guess would be bad gas/high ethanol content.

Originally Posted by Proph

How often are you guys seeing this happen? On my M54 engine, it's happened twice in the 1+ year that I've own the car. I'm not too worried.

Once or twice a week on a daily driver.

Originally Posted by aestheticstorm

Once or twice a week on a daily driver.

Edited. Mine doesn't stumble on idle. Mine stumbles on startup. I need to pay more attention to what I'm posting.

Originally Posted by GrantM62

Edited. Mine doesn't stumble on idle. Mine stumbles on startup. I need to pay more attention to what I'm posting.

Mine does this from time to time too but it has never stalled. It presents itself immediately upon turning the ignition. Turn the key. Car revs to 1000rpm or so per usual, falls rapidly to just under 500rpm and then goes right up to the usual 700rpm or so range and settles at around 600rpm within 15-20 seconds. It concerned me at first but it really is so infrequent that it doesn't worry me all that much.

Originally Posted by JCz04Bimmer

Mine does this from time to time too but it has never stalled. It presents itself immediately upon turning the ignition. Turn the key. Car revs to 1000rpm or so per usual, falls rapidly to just under 500rpm and then goes right up to the usual 700rpm or so range and settles at around 600rpm within 15-20 seconds. It concerned me at first but it really is so infrequent that it doesn't worry me all that much.

Please don't hijack this thread. What you're referring to is discussed here: http://www.bimmerfest.com/forums/sho...d.php?t=443047

This thread is for diagnosing a stumbling engine at operating-temperature idle.

For the record, mine has never stalled. Once it stumbles, it regains its composure and it never does it again for another week or so.

Originally Posted by aestheticstorm

Please don't hijack this thread. What you're referring to is discussed here: http://www.bimmerfest.com/forums/sho...d.php?t=443047

This thread is for diagnosing a stumbling engine at operating-temperature idle.

For the record, mine has never stalled. Once it stumbles, it regains its composure and it never does it again for another week or so.

Sorry. I thought GrantM62 was the OP.

I can say that my 330Ci had an issue where its idle would stumble and, sometimes, stall out. It was diagnosed to be a faulty DISA valve but I don't think the S54 has that component. Dunno...

My Z3M with S54 engine used to do something very similar when approaching a junction and the clutch was depressed, sometimes dropping to 400ish rpm before returning to normal idle. After removing and cleaning the Idle control valve and changing the air mass meter(incase the air temp sensor was failing) both to no avail I had BMW reprogram to factory default and its been cured since.

No issues since I reinstalled the charcoal filter. For real.

Just to chime in, mine does this once or twice every few weeks. I am from SoCal, so temperature are not extremely cold. Just like the others have posted, it will dip down to ~500 or so, and correct itself back to normal operating rpm @800-900 until it happens again a week or two later.

I use only top tier fuel 91octane Shell or Chevron, and use Techron every 5000 miles before an oil change.

I purchased my car used and do not see anything before my paper filter, so I'm guessing the charcoal filter has been removed.

Take it easy, first off to be a BMW owner you need to understand that sometimes there is no reason why things happen the way they do, they just DO!!!

I have had my MZ3 (S54) for 9 years now and it has alway done corky things, that being one of them! I treat it like she's telling you that she's still in control. As for you stalling I don't think its your cars fault (sorry). Word of advice never go looking for a problem with you BMW when you don't have one $,$$$..

But honestly its a common problem in the S54 so don't let it bother to much she'll be fine.

Just adding my name to the list - this has happened to me since my car was new, maybe a handful of times in a month. Everything is completely stock.

my experience is these are often fuel brand or grade issues.

Young people.

The S54 is an 11 to 1 compression ratio engine, with very aggressive cams.

In the old days, before VANOS and all the other computer goodies, and engine with these specs would not idle AT ALL until fully warmed up (including oil). It would stumble, hesitate, buck, and just act nasty.

So a bit of stumble at idle is to be expected. Especially when cold or just starting to warm up. Consider it proof of a high performance engine.