Here we go again.. After fixing the idle switch by readjusting the linkage, my idle is now perfect, but...

...after learning from Ned that the ICV is supposed to equialize the idle (thank you again Ned)... I found out that my rpm's still are dropping by about 200 when I turn on the a/c. Very minor problem in comparison to the one just solved, but I gather rpms shouldn't be dropping when a/c is turned on because the ICV should be compensating to let more air in??

Anyone have any opinion on this one??

84, with your car warm and idling. Disconnect the ICVelectronically. Where does your idle go to then? Do the same and disconnect the AFM and where does your idle go? Don't touch your pedal either time.

Don Mo - are you saying to disconnect the ICV with or w/o the A/C on? I know w/o the A/C on, there is no change (I've already done that this morning).

As far as the AFM, I know from another experience this morning that if the plug is disconnected, the car won't start. Not sure what would happen if I disconnnect while in operation, but I can try.

To clarify, do you want me to run the car at normal idle (850 rpm) or do you want me to turn on the a/c (200 rpm drop) and then pull the ICV and AFM plugs off their terminals?

I'm at work now but I can try later when I get home tonight...

DonMo, did the tests tonight. To answer your question.

-With the engine idling and the a/c off, there is no change in idle when i remove the ICV plug or the AFM plug (done one at a time).

-With the engine idling and the a/c on, there is a slight decrease in idle when i remove the ICV plug. When I remove the AFM plug (after putting the ICV back), there is a slight increase in idle. Still, idle is slightly does drop by about 200rpm w/ a/c on. So is this normal then?

I'm not sure what you are looking for (or why you asked the question), but let me know what you think based on these results. Thanks.

You did right, I was checking to see if the icv and afm settings were right. To me both are working as they are supposed too and adjusted right. The load of your compressor is dragging you down 200 rpm. I am not sure how the Motronic is supposed to adjust for that, Maybe Steve W can chime in here. Iknow the Motronic has an ac input or output wire (not sure which) on the connector. My guess to turn the ac off under load.

Okay, thanks a lot DonMo. SW, if you know if this is normal, that would be great to find out. I was just wondering since Ned mentioned the ICV was supposed to stabilize idle under increased loads, I thought ideally it would be great if the ICV could keep the idle at 850 rpms when the a/c is turned on??? If there was some way to "tweak" things to keep rpm's steady even when the a/c was turned on, that would be ideal. If not, and rpm is supposed to decrease, I suppose I would just have live with it then... Thanks again...

So your mixture was wrong and the idle switch did not work. Who could have guessed at those two things?.

"So your mixture was wrong and the idle switch did not work. Who could have guessed at those two things?."

PBH, your statement above is clearly incorrect. The idle switch had absolutely nothing to do with the low idle problem. The low idle problem was attributable ONLY to the mixture. In retrospect, only SW was dead on right in his reply, and no one came closer to diagnosing he problem in one shot like that. Only after i adjusted the mixture, for the reason explained below, the idle switch was intermittently not making contact when I let off the throttle, but this was a separate and distinct problem that occurred after the fact. If you understood how the idle switch worked, as well as the scope of my problem, you would not have misstated the solution to my problem like you just did.

I already knew how to diagnose and solve the idle switch problem before I posted the question and that was NOT the reason for my post. Something like that was easy for me to diagnose and resolve and I was not asking for help on that issue. I only posted that in the conclusion just to be honest about what was happening, but again, it was clearly a different issue that occurred after the fact, and was not encompassed in the symptoms posted in the original problem.

The only reason the idle switch was not set properly is because SW had mentioned I should try to adjust the linkage so that the throttle opened all the way under full load and that 1/3 of the cars are not set properly. Apparently i did not correctly adjust it so "sometimes" the idle switch would not activate when I release the throtle. Again, this was a separate and distinct problem attributable only to my adjustment of the linkage, and had absolutely nothing to do with the low idle problem. Since then I have adjusted the height of the gas pedal and now my linkage seems correct where the throttle plate pretty much opens all the way when the pedal is floored, and the idle switch is always making contact upon release.

It was very easy for me to tell when the idle switch was intermittently not making contact. I would let off the throttle and the idle would stay at 1200 rpm's and after several seconds drop to 800. This meant that initaily the idle switch was not making contact upon the first several seconds after releasing the throttle, but eventually made contact and then the rpms dropped to a normal level. This also proved that the switch was in fact working, and that it was just the linkage and/or actuating lever that was not properly adjusted.

So to respond to your statement, when I posted about the low idle I knew it was something other than the idle switch and I was asking for specific help on that issue alone. The idle switch CLEARLY was NOT a factor in the orginal problem, and the symptoms I posted clearly were not affected at all by the idle switch.

This is why I told you I thought it was a waste of time when you kept insisting that I do the "exact procedures, step-by-step, with a meter, as shown in the manual" related to the idle switch. Although you apparently took offense at my reply, no offense was meant. I hope this clarifies things for you.

I may not be comprehensively knowledgable about my car as SW is, but I do believe what little I have studied in depth and know well (like the idle switch), I know well. If I don't know, that's when I will ask. However, I do appreciate your inital concern, advice and attempts to help me with my problem even if it was not completely on-target. I sincerely appreciate your effort even though I might only be a lowly electrician and not an esteemed electrical engineer like yourself... Thanks.

Snipernick, you might want to post a reply to this thread when you finally fix the idle problem on your CIS car. Although my posts may help people with motronic cars fix a similar problem, we still don't know how to fix the same problem on a CIS.

If our symptoms are exactly similar as you stated, from what I've learned on this board, you too may also be having a lean mixture issue during warm up. And the there may be some similarity in car's design that will richen the mixture when it hits normal operating tems, which would explain why our idle problems go away at normal operating temps even though we have different systems...

If you assume you might be having a lean mixture issue at warm up and figure out how to adjust it, your problem may probably go away, as mine did....