Cleaning the ICV, idle control valve.

[Snitzler]

I was checking my engine and decided that I would clean the mysterious ICV. First off, I did try the ignition switch on but not started and I could feel the ICV vibrating. It is pretty subtle but easy to feel. The ICV detached easily, loosened the upper and lower clamps and 2 nuts that hold the ICV to the engine and it was out. Watch out for those 2 nuts and washers, if they dropped it would probably be hard to find them. I sprayed brake cleaner into the inlet and outlet until it ran clear. There wasn’t much gunk in there. Shaking the ICV didn’t produce the clunking noise that I expected. Rotating the valve through the long axis produced the clunking sound. I let the brake fluid evaporate and then gave the valve a shot of silicone spray. Installation was the opposite of removing the valve. The car idles the same.

[Discseven]

Nice pics Snitz

[Jesse16]

Compliments on the nice clean engine BTW. Obviously a well maintained car !
Is it finally warm enough in Canada to go out and dirty it up some ?

[shadowjack1]

Nice write up. Thanks

[jlex]

Nice pix. However, from what I'm reading you should keep the silicone spray away from your intake system. It supposedly kills O2 sensors and/or other sensors. Manufacturers of car products will tell you if their item is "sensor safe" so be careful with what you're using.
It's also why I don't use a silicone product (syl-glide) like others do on the O rings when replacing the collapsible oil return tubes. Regular grease works just as well for me, so I'm not going to take a chance of contaminating the engine with a product containing silicone.

[911obgyn]

I dont take the bracket off of the engine I loosen the clamp that holds it to the bracket its easier to find with a magnet on a stick. What Idle issues are you having?

[Snitzler]

Car starts and runs great. When the engine is warmed up the idle will drop to around 600 and the engine will shake and then it struggles to get back to around 800. It takes a second or three to get back to 800. The engine won’t do it for a short idle only when sitting for a light or traffic. Reminds me of an engine loading up because of rich mixture.

[jlex]

Would be nice to be able to borrow a good ICV to see if yours is bad, although it sounds like a vacuum leak to me. A smoke test can rule that out.

[911obgyn]

Does the Idle change when it is warm and you remove the oil cap? if it doesnt you have a vacuum leak. lots of threads where people have found intermittant vaccum leaks cracked lines to oil tank, brake booster, etc. lots of rubber bits that are not too hard to replace.

[OK-944]

I'd had been chasing increasingly bad idle symptoms on my 85.5 944...starting with a high idle (1.5 K) after warmup, progressing to include an intermittent idle cycling between 1 and 2K's, and ultimately having this cycling occurring at startup - so I unplugged the ICV and nothing changed...indicating a fault in the ICV.

I then removed and cleaned the ICV as you did...and tested with 12volts (pos. to middle ICV terminal, neg. to outside terminals) - but noticed only sluggish response. So I took the ICV apart...bending the metal tabs and removing the commutator assembly - and what a mess! Commutator spindle had serious gouges...and contact "bumps" on the three brushes completely worn off! So I cleaned everything up with emery cloth and bent the brushes inwards, reassembled and reinstalled the ICV - and my car now (finally!) idles perfectly...both at startup and at running temps.

I'm guessing that my "fix" will prove temporary...and that I'll be needing a new ICV before long. Not sure if I'd trust a used one after my own findings. Too bad that these ICV's are now so expensive new, and apparently only available from Porsche (no more aftermarket units, at least for my 944). Some have suggested that ICV's from other manufacturers might work - but I have my doubts about this.

[chuckr]

I tried the cleaning thing, a couple of times. Only seemed to be a temporary fix. Replacement was the solution.