idle at 500 rpms in Drive, 87 420 SEL

[RKreutzer]

Hi everybody,

My idle is a bit low at 500 rpm in Drive. It is about 750 rpm in Park and thus ok. Turning on the AC does not lower the idle any further, which indicates to me that there is some idle control still working.

I researched the archives and located the "idle control valve". As per previous posts, the idle should increase to 2000 rpm or higher, when the plug is pulled on the idle control valve. When I do that, idle goes to about 1700 rpm. The resistance of the valve is about 4.5 ohm.

I took the valve out and cleaned the attached hoses, but they were not that dirty. If you look at the attached picture, you can see the inner "plunger" ot the valve. For you experts who have seen a new valve or have access to one, does my valve look ok or is the plunger not going far enough?

Also, I seem to have a faulty fuel pump relay. My pump does not stop after about one second, when the ignition key is placed in pos. II or just before the start. (It used to stop until about a month ago) Could that fault in the relay have anything to do with a low idle?

What else can I test now?

Thanks for your help already in advance.

Reinhard Kreutzer

[RKreutzer]

here is the location of the valve