1990 525i - rough Idle, stalling, and a wild ride.

[abler]

Tonight the temperature showed 22 F on the dashboard and my 1990 525i started acting up, I almost didn't make it back home. Here are the symptoms:

1.) When warming up the car, the idle jumps back and forth between 1,100 rpm and 400 rpm, and almost stalls at 400 rpm.

2.) When I start to drive it, the car bucks like a wild horse and stalls a couple of times.

3.) After a while, I can drive it in 3rd gear (2nd seems better). While the car doesn’t respond as it usually does, it's drivable.

4.) When I finally get home in my driveway, I try a couple of things and this is what I observe:

- In Park, the idle jumps back and forth between 1,100 rpm and 400 rpm.
- In Reverse the idle is constant at 750 rpm (smooth).
- In Neutral the idle jumps back and forth between 1,100 rpm and 400 rpm.
- In Drive, 3rd, 2nd, or 1st gear, the idle is constant at 750 rpm (smooth).

The car never has this problem in warmer weather.

Anyone care to take a crack at this? All replies are most appreciated.

Able

[Tiger]

ICV... tap on it to see if engine settles down. There is a thread on this.

[abler]

Tiger,

When I started my car this morning the idle started jumping back and forth between 1,100 rpm and 400 rpm while in Park as it did last night. I did what you said and it looks like it did the trick.

The ICV is somewhat pricey. Do you know if I can spray throttle cleaner into the two hose ends on the ICV to clean it, or will I have to purchase a new one?

I have attached a picture of what the 1990 525i ICV looks like. It is mounted on top of the engine in plain view.

Regards,

Abler

[Tiger]

yes... clean with carb or MAF cleaner and shake until no more gunks...

[Morgenster]

Tiger,

When I started my car this morning the idle started jumping back and forth between 1,100 rpm and 400 rpm while in Park as it did last night. I did what you said and it looks like it did the trick.

The ICV is somewhat pricey. Do you know if I can spray throttle cleaner into the two hose ends on the ICV to clean it, or will I have to purchase a new one?

I have attached a picture of what the 1990 525i ICV looks like. It is mounted on top of the engine in plain view.

Regards,

Abler

Perfectly do-able. Just take it out spray it in both ends and let it run out and it'll work better. Worked for me too when I had similar symptoms. That was a year ago and it still works fine.

[abler]

Perfectly do-able. Just take it out spray it in both ends and let it run out and it'll work better. Worked for me too when I had similar symptoms. That was a year ago and it still works fine.

Did you have to purchase new hoses from BMW after removing and cleaning the ICV valve?

[M20Turbo]

Did you have to purchase new hoses from BMW after removing and cleaning the ICV valve?

Replace the hoses if they need it, check to see if they any cracks anywhere, while your at it check ALL the hoses for any vacuum leaks as it will contribute to your rough/searching idle. Take the ICV out of your car and when you spray the cleaner in the ICV, shake your wrist back and forth fast enough to help move the little gate more freely. Sometimes the ICV is actually bad and you will need to replace it, but it doesn't hurt to try cleaning first. It's when you go to purchase the ICV that hurts.........

[genphreak]

The M50 is prone to horrible leaks. Check the ICV > intake manifold connector and hoses, also the connector going into the valve cover at the front.

Many hoses tend to get loose in old age and allow air in.

Most importanbtly, check your trans fluid. This could mean your trans fluid level is too high, the fluid too worn (ie brown instead of clear red) or the clutches and/or speed sensor are dying a miserable death.

Move fast for its the trans, you may be pushing your car to the nearest rip-off shop sooner ratther than later.