As my 1994 2.8 12v C4 cuts out at stops, I removed and cleaned the Idle Control Valve, but it made no difference. The ICV seems to be working to some extent at least, as if I disconnect it after starting a cold engine it cuts out immediately. When warm, disconnecting it causes a very slight drop in idling speed.

However, my multimeter says there is NO resistance across the terminals, instead of the 7 to 11 ohms specified by Kris Hansen in his Tech Article on ICV removal and cleaning (which I found VERY helpful, thanks Kris!). What does this mean?

Barry Stuart

 

no resistance as in OL as in open? no resistance its really possible, any wire/complete circuit has some sort of resistance.

How about DTC's? You have a check engine light causing any codes? those could be very helpfull

 

Well, I guess my little multimeter may not be that accurate, but to be precise it shows about 0.1 ohm resistance, the same as if I connect the meter leads to each other - in other words, a full connection. No DTCs or engine check lights, but that may not mean anything, as it looks as though the previous owner hacked the circuitry somewhat to fit a non-standard immobilizer. I don't quite understand how the ICV should work: is it supposed to open as the revs drop when you stop, and then close again?
Barry Stuart

 

I should add that the stalling problem is recent, and was not there when I got the car, so is unrelated to anything the previous owner might have done! Further to my last question on the ICV, what controls it? Is there a relay or something, and if so could that be where the fault lies?

Barry Stuart

 

I'm just going to throw this out there but rough idling can also be caused by the o2 sensors starting to go. If it worked when you got it and it started to go bad later, maybe its not the icv.

 

She actually idles fine, hot and cold. The problem emerges just when you stop at a traffic light or stopstreet, the revs drop below normal idle of around 800rpm. Initially she recovered back to idle speed, but now she almost always cuts out. If I left-foot brake (tricky to do this smoothly!) and keep the accelerator slightly depressed I can prevent it. It seems that whatever is supposed to "catch" the situation is not acting enough or quickly enough? I gathered from reading other posts that it is the ICV that does this. Maybe I misunderstood? Either way, that total lack of resistance makes me think the ICV may be faulty: but it's expensive, so I'd like to make sure before ordering one!
Barry Stuart

 

I have exactly the same problem and wondered if you have fixed it. Everything you have done I have done with the exception of changing the valve, but not had any luck yet. If you have cracked it I would appreciate your help.

 

(For the record, I did reply to PMD: don't know why it does not show: I said something likeNot solved yet, but I found another append by someone with an older Audi, who said he had fixed the same problem by boring out the glue-plug in the side of his (older model) ICV and adjusted the idle speed by turning the screw within. I note that mine has a similar hole filled with glue or something, so I propose to try the same thing, as soon as I can find a gap to do so. Will let you know what transpires!

The total absence of any resistance does, however, really puzzle me. I wish someone would explain it - or at least confirm what the resistance is on an operational one!
Barry Stuart

 

Let me know how the boring turns out. sonce oyu are going to have the thing removed anyway scour audidiy.com for the thottle body mod. Its make the 2.8 c4 and maybe it will help you run smoother.

 

Thanks for that info: I did not know about audidiy! Does anyone have first-hand experience of the results of that throttle body mod? Seems to me I recall that opening the intake breathing moves the torque peak higher up the rev range?