Cleaned my ICV, need input here. . .
 

I cleaned it using isoprop. alchohol. the piece you can seen down in the holes spins freely, and when i shake it i hear a dull thud as i shake it back and fourth. However, it feels like its barly moving, like maybe a 1/16 of an inch or less, but I have no way of telling for sure.

Does this sound like an ok ICV.

bump

OK, I was hoping someone would answer this question so here's another bump.

Yes, me too. I've cleaned mine (and myself) out with alky and didn't notice much difference. I can't really tell a difference when I unplug the electrical connector from it, so hence it's difficult to tell whether it's actually working. I've searched a bit, but not found much definitive on the subject.

The Bentley has a rudimentary test, but I'd like to hear some more as well,

ianc

It should move more than a 16th of an inch. It is a valve, so it should open the airway and close it. The ICV can be opened up and taken apart. There may be some debris blocking it from moving.

is there a bench test i can do to see if the plunger is working. Like hooking up a 9v batter the terminals?

You've already done the bench test by shaking it back and forth, looking for free movement. When voltage is applied, it vibrates slightly, but I think you would have to vary the voltage applied to get it to open and close.

I see, so then even if the ICV was working fine, if you shook it you would NOT see the plunger in the window of the unit. B/C right now I see nothing when I shake it.

I cleaned mine some time ago but if I remember right it should be free sounding kinda like the sound of an empty paint rattle can. I didn't notice any difference after cleaning it either.

You fellows who are fairly sure yours are working:

What kind of difference do you see in the idle quality when you disconnect the electrical plug from the unit? More when cold than hot? Input here?

ianc

I have NO idea if mine is working or not. One evening I walked out to the car popped the engine lid and went to work. Unplugged it, unmounted it and took it to the work bench. Cleaned with alcohol and soaked it while I ate dinner then went back out to the garage and shook until it sounded like a paint rattle can and "free" sounding. Then I remounted it hooked up the wires and a few days later I took the little lady out for dinner in it. It ran the same. I know, I hate this word too, but I "assume" it's working. Car runs excellent....

EDIT: The engine was cold when I did the work.

Bill,

when you shake it you say it sound like a paint can. How much movement do you think the pluger is moving back and forth?

It seems like it moved about 3/4 in from sound to sound.

Mine sounded more like a dull thud than a free sounding rattle of a spray paint can. I wonder if it is clean or not. Can someone clarify what a new one sounds like? I think that there are several of us that are trying to determine what the correct sound should be.

still confused . .

just got home and looked at the ICV again.

Now i can see the piece that rotates, it rotates freely and smoothly about 1/2 turn. If i stick a pencil with an eraser donw in there and hold it tight will shaking it i get not "rattle" or "thu" up and down whatsoever. I've heard of the plunger, is this the same piece as the rotating piece or is it separate? Can someone explain the exact operation?

Reinstall and Drive It
 

It's a 10 minute job to reinstall the ICV - now that you've cleaned it out, why not just put it back it and see how she does?

well, its a little more complicated than that. I also have my AFM off and will be switching that out (hopefully, if he'll let me) with a friend of mines '87. Also, he as an CO meter that we are going to set my idle mixture with because i fiddled with it a while back when i was trying to diagnose a misfire (turned out to be a plug not pluged in all the way). So I have several variables im trying to weed out. I figured if i could get a handle on this ICV i'd have a better direction.

Im just not sure i understand how the internals work to see if what i see is normal or not. When I cleaned the ICV the alchohol came out clean, no debris.

That's all I look for, It should work fine. It's function is to allow air past the throttle plate, which is modulated by the ICV valve. This is how the Motronic system controls the idle speed. The voltage applied to the ICV varies with the program in the DME under different conditions; ie: cold start, or normal temp running. As the voltage applied changes, the valve opens or closes off the bypass tube.


If you are chasing a "hunting idle" problem, I would strongly suggest you confirm your CO mixture setting with a gas analyzer before making any further adjustments or replacements. The mixture is very precisely metered through the AFM, and if not set correctly, you can be replacing parts that don't fix the problem.

edit: I should read all the posts before running on about stuff that's been done.

Anyway, I just resolved a "miss" problem after wrangling with the mixture, AFM, Dizzy, etc., only to find a poorly firing plug. Replaced the plug, and all is well. This stuff really does all seem to work together, so the symptoms of failure often point to just about any part of the whole complex system.

I hope its just an "hunting" issue. This all started when I started the car the other day and the bounce up and down wildly between 800 and 1500 rpm or so. Then as i started pulling away the car when to about1200 rpm +/- then bucked. It would also start pulling, and then it was like the ignition cut out - nothing for a second or so, then the engine cut back in. I've got an DME on the way, and i've done a just about all the resistance checks i can, and they all come up good. Even the ICV. The cleaning bit was more of an insurance policy if you will. However, i kept reading about a plunger than could get stuck and i wasn't sure what the plunger was or what a stuck one would feel like.

Sounds like you have a series of problems. I would start with replacing the DME relay (I hope that's what you meant, not the DME itself). Then get the mixture set correctly. If you still have a hunting idle, I would suspect the AFM. It has a potentiometer inside that can get a worn spot that causes the voltage pickup to be erratic, which can cause all sorts of issues. There is a way to re-position the pickup arm that glides across the potentiometer that I would try before replacing the entire AFM. By far, however, my CO mixture setting has had the greatest affect on the performance and idle.