M20 icv problem?

[Mullet Bullet]

Ok so I've had a weird idle since I got my car. It's a 1990 325i.

Basically on cold days you start the car and it starts then drops to about 600rpms. There is no cold high idle what so ever. I pulled the icv and sprayed cleaner in it to no avail. The wires look fine but when the car is running and you unplug the icv nothing happeneds, no change in idle at all. Is this normal for the m20's?

[brian h]

Possible vacuum leak?

[Mullet Bullet]

thought about that, going to bring my car into work and smoke the intake out. the intake gasket is brand new but im not sure about the vacuum hoses and such.

[brian h]

I just had this problem with my m20. Check all the hose clamps and make sure the valve cover is tightened correctly.

[Mullet Bullet]

well all the hoses and top end gaskets are new since i just rebuilt the head and all that. i know the oil pan is leaking pretty bad and thats going to get changed in the next few weeks once i source a E36 rack to go in at the same time.

[Mullet Bullet]

tested the ICV tonight and it ohms out properly. i also grabbed the specs on the CTS so ill check that tomorrow after work but the CTS and connector look a good bit newer then all the others in the engine bay. i guess i can swap in my spare DME as well and give it a try.

[bastianshaw]

update?

[motozach69]

Is your intake boot torn common problem to run into and my car ran like that till I changed it thats if it is a vacuum leak

[rlddlr53]

I have 2 ICV's for sale :)

[Mullet Bullet]

still having the same issue, intake boot seems fine but im going to get a new one since they are under $20 anyways. also just replaced the coolant temp sensor and did a coolant flush for the winter prep so i know thats wasn't the problem.

[blocke]

Has anyone ever messed with the throttle plate adjustment screw? Maybe its too far open, allowing air in at idle and doing the ICV's job, hence no change when you unplugged it.

[Mullet Bullet]

No it hasn't been messed with, and if it was I would have a higher idle compared to mine that sits at like 600rpms or so.

Also if it was a vacuume leak then I would have a higher idle, but I don't. Another thing I did notice though is that when I turn on the a/c the idle raises maybe 100rpms but smooths out.

[motozach69]

Sounds dumb but check the air filter it sounds more like you have an engine starving for more air flow idk stupid idea but if I was their we could figure it out it sounds like you do routine maintenance on your car and part failure is common anything related to idle control you haven't ruled out

[motozach69]

The ac compressor draws more voltage from the battery causing the engine to idle higher to maintain proper voltage to the cars componets thats weird call me a moron but I went to a starting and charging system class where the renowned teacher said poor voltage can cause runability problems sounds like your case but you won't know till you check off options that causing your symptom

[Mullet Bullet]

Sounds dumb but check the air filter it sounds more like you have an engine starving for more air flow idk stupid idea but if I was their we could figure it out it sounds like you do routine maintenance on your car and part failure is common anything related to idle control you haven't ruled out

i get were you think a restriction could cause the problem but that would be more pronounced under a load and at higher RPM's which is when the car runs flawlessly.

The ac compressor draws more voltage from the battery causing the engine to idle higher to maintain proper voltage to the cars componets thats weird call me a moron but I went to a starting and charging system class where the renowned teacher said poor voltage can cause runability problems sounds like your case but you won't know till you check off options that causing your symptom

no the a/c doesn't draw any more voltage then the headlights or brake lights, it creates a higher mechanical load, and the ICV bumps the idle up to compensate for that added load(which my ICV does).