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Discussion Starter #1
Started just recently – and maybe related to the fact that I don’t DD this car anymore, but not sure.
Typically, when you start the car, the revs go up to 1200-1400 rpm and as the car warms up slowly drops to the 650 or whatever the idle revs for the engine once warm, right?
So, my car quit doing this. When I start it, it barely goes to 1000 rpm, might (or might not) start stumbling right away, dipping to under 400 sometimes, recovering, then stumbling again. After a few seconds it usually goes to 1200 or so and then warms up and idles normal after that. But that initial startup sequence is not normal, it has never done that before – what gives? Sometimes when I try to rev it (lightly) while it stumbles, if just acts as it is about to stall. Kinda like misfiring, or bad coil pack, but they seems fine - could this be something else?
No codes, no lights. Once warmed up, car drives normal. No loss of power, smooth idle. Once I shut it off and then restart it, I get the dreaded idle fluctuation (always had it), but now it seems more pronounced. Once I drive the car for some time, it settles and idles fine again.
So, is there are anything I can check, test, or do to diagnose or remedy this? Anybody had the same issue? 06’ 57K miles.
 

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Has the car been sitting for a long time since you don't drive it daily any longer? Mine starts by what you define as normal, but while in neutral and revving seconds after starting it from cold it reacts by that almost stalling behavior you describe. It goes away after you idle/drive it for 30 seconds or so. It has always done that so it is likely not unique to your 'issue'.

The warm restart idle fluctuations you describe may indicate you need to replace the carbon filter in your DTML (fuel vapor recovery) system. Behind the lining under your right rear wheel well lining. Then again, the VANOS actuator may be a root cause here as well.

Also, when was the last time you replaced your fuel filter? Mine drove like a 'different car' and I just replaced it out of preventive maintenance measures. No exaggeration! I had 65k on it when I did so. And I drive it daily through New England winters. If the car has been sitting for a long time, perhaps the filter is negatively affected somehow.
 

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Discussion Starter #4
No codes.

The car has been sitting for no more than 5-7 days at the time, so I wouldn't say it was sitting too long. I drive it once a week, maybe once every 8-9 days for about 100 miles. Used to drive it every day though.

Is the carbon filter you mention a DIY? Need to look into this. Never replaced fuel filter. Will look into this as well.

VANOS actuator? Could you please elaborate? I'll search too.

Thanks!
 

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No codes.

The car has been sitting for no more than 5-7 days at the time, so I wouldn't say it was sitting too long. I drive it once a week, maybe once every 8-9 days for about 100 miles. Used to drive it every day though.

Is the carbon filter you mention a DIY? Need to look into this. Never replaced fuel filter. Will look into this as well.

VANOS actuator? Could you please elaborate? I'll search too.

Thanks!
VANOS actuators/solenoids control the CAM shaft positioning/timing with VANOS oil pressure. Do a search. There is a lot of talk about these things. Dirty oil and particulates will clog them. So, change only and filter every 5 grand. There are DIS / ISTA/D Rheingold tests you can run to check their "health". There have been idle fluctuation reports that were resolved by replacing them. (Cleaning them is a bit hopeless). But start simple with the filters. The actuators are expensive. So, rule out the easy stuff first.

In the DIY section:
http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/235105-diy-changing-s85-vanos-solenoids.html

DMTL canister/filter: (I realize that there is no DIY for it....but it is relatively easy. Get a copy of BMW TIS software). Some words about it:
http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/445777-crazy-vacuum-fuel-tank.html
 

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Discussion Starter #6
Thanks!
 

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OP - before you go chasing your tail on the idle, do this simple test. Check your voltage in the secret menu right after startup. I had the same conditions described, but occasionally the HUD and radio would flick on and off (overvolting). Voltage menu confirmed this. Idle seemed to be following the varying voltage output.

I swapped out the $40 Voltage Regulator, and now my idle is rock freakin solid. Unbelievable how much better off this car is now with a simple $40 part. It shifts smoother and warms up like a brand new car.

Check this before you do anything. These VRs are consumable items and cheap / easy to replace.
 

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Any updates on rough idle issue?
 

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Issue has been Fixed. Replaced Alternator with Voltage Regulator - Valeo 439559 is the alternator that comes together with VR. Relay part number is

Also Replaced Relay that is responsible for charging because it was getting very hot and causing battery drain issues. Part number: 61366901469 and it sits in the trunk inside the fuse box.
Replying to multiple threads (some of them years old) is rather annoying. Even worse this thread has nothing to do with you or your problem. Personally I never bothered to reply to your questions for this reason. I'm sure I'm not the only one. Open a new thread next time.
 

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Discussion Starter #14 (Edited)
My issue seems to have resolved itself, but its hard to say what I did (or didn't do) to help it, as I have done quite a few (seemingly unrelated) things to the engine. I still get slight idle fluctuations when the car is warm, but I just chose to ignore these now :)
I did replace both TBAs and I think that was the culprit.
 

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If you dont want to help thats fine. Im trying to help people to resolve issues with their cars and future members. No point to open up a new thread when this thread has already alot of discussion about it. IF you are annoyed at a notification in your email about this thread being revived - thats your problem.
 
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