Loping idle until I take out the dipstick or unscrew oil fill cap.

[brian0128]

This isn't on my 87 E30. It's actually on a 1983 520i with the 6 cyl M20 motor. The motors look really similar except for the rubber intake tubing for the intake. What would make it have a strange idle that sounds like a vaccum leak? Once I take out the dipstick or unscrew the oil cap, the idle becomes steady but it's still high, around 1500RPM. I can't turn down the idle screw any more so I was thinking it might be the cold start or the idle control valve, but I thought I'd post here first to figure it out.

[325iCabrio]

It could be that the throttle is adjusted too tight. Check out this idle page.

[cthulu703]

Check to see that the breather is unobstructed. Also, possible ICV valve?

[brian0128]

Check to see that the breather is unobstructed. Also, possible ICV valve?

I am new to the BMW scene, sorry. I've been reading as much as possible over the last 2 weeks that I've owned a BMW, but where is the breather?

As for the ICV, I know where it is on my 87 320i (right up top next to the intake) but on this 83 520i, the intake is the same, but everything going up to it is a little different and I'm not sure where to find the ICV. On my 87 I have Motronic, on this 83 I am pretty sure its the other type of L-Jetronic????? (it's late, I might have spelled that wrong or misquoted it) so I don't even know where to find the ICV on it.

In case your wondering why I'm working on a car that I know nothing about....I'm in the US Army and stationed in Germany and everyone here has a BMW....;) .... my 87 is in great shape, a 1987 with only 135k kilometers on it with a mint interior and exterior...problem is that it is a 320i with the small motor with no torque. My buddies car was given to him and it's a 1983 520i in mint condition body wise...just a few motor problems. It's driveable, just has an idle problem. Don't flame me for knowing nothing about these cars. I have done so much reading over the last 2 weeks to get my car to pass the inspection here in Europe and it worked!!!!! This forum rocks! I fixed all of the small problems that I've had with the car so far, and now I'm helping other members in my unit with their cars.

[AndrewBird]

When you take out the dipstick or remove the oil cap, you are creating a vacuum leak and essentially making the motor run leaner. Since your idle gets better when you do this, this leads me to believe that the A/F mixture at idle is too rich. If that is the case, I would check your cold start valve. They are know to go bad and will default to the richest setting I believe when they do.

[brian0128]

When you take out the dipstick or remove the oil cap, you are creating a vacuum leak and essentially making the motor run leaner. Since your idle gets better when you do this, this leads me to believe that the A/F mixture at idle is too rich. If that is the case, I would check your cold start valve. They are know to go bad and will default to the richest setting I believe when they do.

Where is the cold start valve?

[SpecM]

-The cold-start valve on US-etas w/ Motronic 1.0 is on the end of the intake manifold, right above the valve cover. Not sure on the Euro, tho.

[TUD]

According to realoem the cold start valve was not installed on Euro M20s. p/n #7

[brian0128]

Since there is no cold start valve and I can't seem to locate the ICV, what now? I'm taking pics of under the hood so I can post them and everyone can see what I see.

[Rocla]

Since there is no cold start valve and I can't seem to locate the ICV, what now? I'm taking pics of under the hood so I can post them and everyone can see what I see.

L-jetronic engines don'y have electrical ICV.

On that earlier posted realoem picture look at the part #5, it's the idle adjuster, track the rubber hose from it and you'll find the rheostatic cold idle valve below the intake manifold.

The looping idle is propably because of the ICV is stuck open, revs will raise up to 1000 rpm and then the coastal cutoff is shutting injector feed, until idle drops below ~900 and cycle starts over again.

EDIT: http://www.realoem.com/bmw/showparts...34&hg=13&fg=15

Part # 11ADDITIONAL AIR SLIDE VALVE

Is the part I ment.

The rheostatic ICV is not serviceable and cleaning usually doesn't help.

If you cannot get new rheostatic ICV, plug hose from ICV to manifold and adjust idle speed correct when engine is warm. Doing that will disable cold start idle raising, so car will not idle properly(if at all) when cold.

EDIT2: Euro spec m20b25 allways have Motronic, M20b23 allways have l-jetronic and m20b20 have l-jet untill M.Y. -88 after that they have motronic.