940 GLE running rich, rpm won't drop

[TonyS9]

If the throttle body was gummed up, did you check the other breather pipes, particularly the small breather to the oil separator.

[codinacan]

Originally Posted by TonyS9

If the throttle body was gummed up, did you check the other breather pipes, particularly the small breather to the oil separator.

No, i haven't. In fact i'm not sure i know what the oil separator is. One more thing to check

[codinacan]

well, mileage has not improved, although driving it has improved. i just found out that if i clamp (with my hands, not with a clamp, but nevertheless quite firmly) the iacv, it makes absolutely no difference to the idle. but if i unplug the iacv all sort of idle craziness occurs, and the idle speed screw is already set for the minimum speed.
in diagnostic mode, the iacv clicks and ican feel it move freely.

[Rversteeg]

With the hose clamped, the idle speed should drop to 500 rpm.

[codinacan]

Originally Posted by Rversteeg

With the hose clamped, the idle speed should drop to 500 rpm.

i've just been checking around, and it sure does not drop, in fact nothing happens. i pulled the throttle linkage, including the return spring, apart to see if there was anything weird, and everything looked normal, but once again, there's a little play, and if i rotate the butterfly shaft counterclockwise, in the direction of the idle speed screw, it moves about a hair, and idles drops to the the point of stalling.
so, i'm guessing my throttle body is the culprit. but when i cleaned it, the butterfly would close perfectly, at least to the naked eye.
i doesn't make sense, if the butterfly is fully vertical when the throttle is not pressed, why in the world would the idle drop when pushing it to the "closed" position?

[Steve940estate]

I don't think the throttle plates are intended to shut completely I think there is supposed to be a small gap. I will have to go looking for the section in the manual to confirm it though.
It does sound like you have a leak somewhere though. From memory there are a few pipes from the inlet manifold leading to various things like the brake servo, bypass valve and boost gauge if you have one so it might be worth checking those if you haven't already.

[codinacan]

Originally Posted by Steve940estate

I don't think the throttle plates are intended to shut completely I think there is supposed to be a small gap. I will have to go looking for the section in the manual to confirm it though.
It does sound like you have a leak somewhere though. From memory there are a few pipes from the inlet manifold leading to various things like the brake servo, bypass valve and boost gauge if you have one so it might be worth checking those if you haven't already.

i was reading my haynes book of lies for the 300 series (yeah, i love those little bricks) and for the b200 it says it should have a 0,1mm gap. i don't have a gauge feeler, but from looking, it seemed pretty tight.
the leak, could explain most of my symptoms, just having a little trouble finding it. but then again, the story of my life.