E30 Zone

So today i decided to clean out my air intake/ throttle body on my M20.


-Did all that with carby cleaner, dried nicely, put all back together with cleaner, tighter seals than before, checking all pipes etc for conition. All was mint. All elec connections clean.

-Once it was all back together, the previous 20 sec sliiiight idle fluctuation had gone from 700- 1000rpm, to 500- 2000 rpm non- stop.

Now I know about vacuum leaks, i know the function of the ICV, and i know about air flow meters (basic operation anyway).


-After taking the car for a cobweb blow- out, (NOT a thrash, but a good run for 15 min) the fluctuation had gone- and on starting, the car would struggle to stay at 400rpm, and then stall mostly.



Tonight with the car cold, it starts fine first pop, but dies instantly. The ICV is doing the normal buzz, but when disconnected it doesnt 'spring' to the open position like i have read they should, instead it stays at the 2-3mm gap same as with engine off and key in 'ON' position (ICV buzzing).

Sorry about the complicated post, but basically MY QUESTION IS:

Should the ICV spring open when disconnected? (non- event indicating shot ICV) could this be the prob?

oooh tricky.
I think you might have a couple of problems here.

First off, because you have cleaned the butterfly of crud it is now passing more air through on idle so I would try to re-adjust this I would expect this to bring the idle speed down a bit

then so solve the hunting idle I would check for a vacuum leak from the inlet manifold gaskets if you have one replace the gasket only a couple of £ from BMW also you my well be right with the icv problem, if you can get hold of one to test it wold be ideal however you could always try to clean it out?

I'm sure someone else will have some other input later on

Early two wire ICVs shut when they are disconnected. Later three wire ones stay put at whatever position they were when disconnected.
Unless someone has moved it before, leave the throttle butterfly stop adjustment alone. BMW set it at the factory, and it doesn't need moving.
Double check that the TPS is working properly (cleaning throttle body often fills the TPS with crap), and also double check for inlet manifold air leaks.
Try starting and idling with the AFM plug disconnected.

Cheers for that guys, yeah i think the TPS will be the next (last) thing for me to check- and yeah it definitely had the chance to fill with crap! ICV is cleaner than clean, and i suspect its operation is fine now. Really does sound like tps......

Did you disconect the battery at any momentt?
Because my ICV wouldn't work properly the 3-4 days after battery changes on mine (don't ask why, there is no reason for it, as I've cleaned it, without any improvement!) The idle was fine after starting, but give it a little throttle, and the idle would then be too low, even dying when warm.
Cured itself after a couple of days.

Thanks guys!! i would never have thought that crud would have gotten down into the TPS! And also i now see that my ICV is fine, and VERY clean haha. TPS wasnt making a 'click' when i moved the throttle before, so i took it off, cleaned it, and refastened it at zero throttle so that moving the throttle would make a 'click'. Car runs and idles perfectly now, and the bonus is that she is minus a whole lotta crap in the air intake!


Cheers!

Nath
NOW, THE NEXT DAY the icv has stopped working (no buzz)

So the ICV is working fine on my mates car, the relays beside the air flow meter are fine also.

what i now remember, is that yesterday (once the engine was warm, so that would explain not noticing the ICV stop) I reset the service lights with a paper clip (read: UNFUSED WIRE) and probably had it on for too long, as i was wondering why the last green light wasnt on.

Is there a fuse of a something somewhere thats stuffed up the ICV due to this? I have early motronic with the pre- FL diagnostic plug.


!!!

Bit of an update again- took the ECU apart and part of the printed circuit board was fried. got that fixed for $35 same day, and now the ICV is working fine, but the car is idling too low! every now and then it dies, but i put this down to the fact that its simply too hard to maintaon a low idle!!

dramas

The car wont idle when cold, and will idle at 450 very lumpily when warmed up.

Could this be a temp sensor? how many does it rely on? Will test the ICM tomorrow as well....