eta idle problems/ vaccum related?

[EtaSport]

My mom's 85 528e has had an idle problem almost ever since we got it. Right now it has about 240k and the motor is all stock. My dad bypassed the ICV because no matter what he did when the car was in park it would idle around 1500. Put it in gear and it goes down to around 800rpm. We used to get by okay by just turning it off in gear. (it would idle normally when cold) So now with the ac on, and the car in gear it will not run without turning the idle up on the throttle linkage, which in turn causes the idle to be about 2 grand when in park. We seem to think it has a major vacuum leak based on the fact that when the oil cap is off or the dipstick tube is out it will not die.

When we hooked the vacuum gage up to it, it read 22 inches. Does anyone know if this is normal or not? Seems to like 22 is more than normal, and doesnt constitute a leak.

My dad is going to get a new ICV as well as all new rubber hoses and probably valve cover gasket as well. Any ideas or suggestions. *Turning the screw in on the ICV all the way in still wont get the idle down low enough when in park*

[DaN]

22 in/hg of vacuum is pretty damn good for such high mileage.
Sounds like it's an icv problem.

Make sure the throttle plate is allowed to close all the way, and the cable or anything else isn't holding it open. Take the rubber boot off the throttle body and make sure the butterfly is closed all the way.

[Ryan Stewart]

Yes, start from scratch. That screw on the throttlebody isnt for controlling idle and the DME doesnt know when you change something like that.

Get a new ICV, its been long enough. Maybe a used one just to experiment with. Check the AFM boot for cracks and the hoses to the ICV and FPR for cracks. If all those are fine maybe its between the manifold and the head.

Oh, and the hose from the TB to the valve cover.

[EtaSport]

Yea, that screw was just to keep the car running when we cut vacuum to the icv. He got a new icv about 3 years ago I'd say. Last night we plugged the old one in and it was even worse. I was going to try and use the one from my car because I have no problems. He is going to just get a brand new one though, but perhaps I will swap mine in tonight.

Also, is it possible that the throttle position sensor might not be set correcty? I haven't checked to make sure its in the right spot. It should click as soon as I start to move the linkage, correct? I assume that we could always try swapping ecus as well. I have an extra eta motronic lying around somewhere.