98 M3/4; Occasional stalling: WTF?

[m3f_empwrd]

:help:



1998 M3 sedan (36k miles, no mods):



Occasionally while stopped in traffic idle speed will dip to just above stalling and then come back to normal idle speed on its own.



Twice in the last two months it has just died while idling at a traffic light; it does this very suddenly, without warning. Gauges all indicate normal state.



I would really appreciate thoughts on this.

[m3f_97BLKM3COU_0f375e15e2]

Is the engine cold when this happens, or is this after driving it for a little bit? Maybe the Idle Control Valve needs to be cleaned?

[m3f_empwrd]

Is the engine cold when this happens, or is this after driving it for a little bit? Maybe the Idle Control Valve needs to be cleaned?



No it doesn't happen when cold; this morning it happened when car had been driven a good 30 minutes.

[m3f_97BLKM3COU_0f375e15e2]

Purchase a nice fuel system cleaner to run in your next tank of gas. There could be all kinds of reasons why this happens. Do you notice any stumbling other than at idle?

[m3f_empwrd]

Purchase a nice fuel system cleaner to run in your next tank of gas. There could be all kinds of reasons why this happens. Do you notice any stumbling other than at idle?



I'll go the Techron route first (check results), then clean the ICV (check results), then fuel filter, in that order obviously.



Where exactly is this idle control valve ?



Advise, and thanx.

[m3f_Norlin]

ICV should be in that hose that connects your air filter box to your engine

[m3f_97BLKM3COU_0f375e15e2]

Actally, it is not that easy to get to. Try the fuel system cleaner first and see what happens. The ICV is kind of buried and you have to remove quite a bit of items to get to it.

[m3f_96M3Power_4547fc3d60]

One of them being the intake manifold...

[m3f_ziggy]

I also have a 98 M3/4 with a similar issue. It happens every now and again (engine fully warmed) but mine has never stalled so i never gave it too much thought other than a "hmmmmmm." Otherwise, performance across the board is great.

[m3f_ubersnax]

my idle just drops to 500 sometimes.. and sits there.. its ridiculously low but no mechanics ive taken it to have any idea why..

[m3f_96M3Power_4547fc3d60]

How do you clean the Idle Control Valve? Or should I just have bmw do it?

[m3f_empwrd]

I also have a 98 M3/4 with a similar issue. It happens every now and again (engine fully warmed) but mine has never stalled so i never gave it too much thought other than a "hmmmmmm." Otherwise, performance across the board is great.



Interesting; as I also own Ducati 748S. Pranged last summer, now being completely customized and better than new:



Black Paint with very small bit of gold pearlescent over.

Gold Marchesini's

Much CF, Ferraci bits

40 & 14 teeth



I'm in small claims court this Friday as a result of an uninsured punk getting ticketed for causing the accident that wasted my sterile Duc. Oh well, good opportunity to re-build (upgrade).

[m3f_Norlin]

Never tried this but read that you should take the ICV out, spray it with some alcohol based cleaner (like monitor spray?) wipe it down. Have the door in the closed position to get at the most carbon deposits. Then after clean, let it evaporate off all the alcohol then spray it with some WD40 and shake it out then reinstall...like I said, never tried it so no clue if it works well, but this is what I read over on another message board but forget which one...

[m3f_Norlin]

Here's the page I saw that I was talking about:

http://www.bmwe36tips.20m.com/unstable-idle.htm

[m3f_FabulosoM3]

I have the problem to once and a while. I heard that you could take it to the dealer and they have an upgraded software to eliminate that bad idle. I havn't done it b/c i might just be getting a new performance chip soon anyways. And i would rather see if the performance chip would work. If not then i'll see from there.