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Topic: Idle how does it work? (Read 2789 times) previous topic - next topic

Idle how does it work?

I have a 1986 3.8L Cougar, when I crank it up it idles fast as usual but sometimes way too fast it seems and also it is really rev ed up when it's hot, is this normal or is there something that isn't set correctly, something worn out?

Idle how does it work?

Reply #1 –
Start looking for a vac leak. Start with all the rubber hoses,then use some spray carb cleaner spray around the throttlebody and intake gaskets to see if idle speed changes. If it does you found a leak.
Brian R.
88 2.3t Ranger
83 TC  gt40p motor,Vortech,TFS1 cam,long tubes,MS PnP,T5,8.8,17x9 Cobra 17s

Idle how does it work?

Reply #2 –
My '85 3.8 does something similar when I start it, after 15-20 seconds it will usually settle down. I don't know if this is normal either.
Cornfed85

1985 Thunderbird - 3.8 V6, C5  :ford:  :birdsmily:

Idle how does it work?

Reply #3 –
I think I've found my problem, my Idle air control valve is shot going to replace it soon!

Idle how does it work?

Reply #4 –
Quote from: CatWoman;456474
I think I've found my problem, my Idle air control valve is shot going to replace it soon!
Your car does not have an IAC valve. It has an ISC (idle speed control) motor.
The motor has a plunger that moves in and out to control the throttle position. The motor has a ITS (idle tracking switch) built into it.
When you take your foot off the gas, the throttle linkage, under spring tension, presses against the ISC plunger. This operates the ITS, signaling the EEC that it is in control of the throttle position. End of how it works lesson.

1. Pull computer codes.
2. Take the air cleaner off and observe whether the ISC plunger ever moves.
3. Here is the adjustment procedure for the ISC motor. Skip the throttle stop screw part. It should be ok unless it has been messed with.

Idle how does it work?

Reply #5 –
Thank you very much softouch I'll check that out before I go out a buy a new one.  But the original ISC is still on the car, it might need cleaned and adjusted, I've read once they give problems you might as well replace them cause cleaning is just a temporary fix, is this correct?

Idle how does it work?

Reply #6 –
Quote from: CatWoman;456479
Thank you very much softouch I'll check that out before I go out a buy a new one.  But the original ISC is still on the car, it might need cleaned and adjusted, I've read once they give problems you might as well replace them cause cleaning is just a temporary fix, is this correct?
Idle air control valves sometimes need cleaning.
Idle speed control motors never need cleaning and rarely ever need replacing.

Idle how does it work?

Reply #7 –
I was waiting for softtouch to reply, haha. He's correct.

Check for sizes codes, adjust, check for vacuum leaks. With cars as old as ours, intermittent vacuum leaks aren't uncommon of the lines are original.

Idle how does it work?

Reply #8 –
Well I do understand the instruction for setting the ISC but I haven't seen the plunger move at anytime when I turn on the switch, it was dirty so I wiped it off with a soft cloth, sure that didn't help anything but it made me feel better.  Anyway if the plunger isn't moving do you think it's worn out or what's the deal with it?  Haven't pulled any codes, have to get a code reader or take to the garage.  Should I go ahead and adjust or wait till I see what the codes are?

Idle how does it work?

Reply #9 –
Hey Softtouch I took your advice and ordered a Champion radiator, I'm excited it may arrive this week!  Cool looking it is and a life time warranty, what else could I want for my Cougar cooling.

Idle how does it work?

Reply #10 –
Quote from: CatWoman;456534
Well I do understand the instruction for setting the ISC but I haven't seen the plunger move at anytime when I turn on the switch, it was dirty so I wiped it off with a soft cloth, sure that didn't help anything but it made me feel better.  Anyway if the plunger isn't moving do you think it's worn out or what's the deal with it?  Haven't pulled any codes, have to get a code reader or take to the garage.  Should I go ahead and adjust or wait till I see what the codes are?

Have you checked for KOEO and KOER codes?
 

Idle how does it work?

Reply #11 –
Quote from: CatWoman;456534
Well I do understand the instruction for setting the ISC but I haven't seen the plunger move at anytime when I turn on the switch, it was dirty so I wiped it off with a soft cloth, sure that didn't help anything but it made me feel better.  Anyway if the plunger isn't moving do you think it's worn out or what's the deal with it?  Haven't pulled any codes, have to get a code reader or take to the garage.  Should I go ahead and adjust or wait till I see what the codes are?

You have me confused with someone else on the radiator.

Trying to save you as much money as possible. Codes can be read-out without a code reader. It just takes a little practice.
If you are not familiar with pulling codes, I am guessing you did not put the self test jumper on. The self test connectors are near the driver's side shock tower.
A straightened paper clip can be used for a jumper.  If you don't have an buttstuffog meter or a test light, I recommend getting a test light. They always come in handy and are cheap.

!.Take the air cleaner off. Notice where the IAC plunger is. Is it touching the throttle linkage pad?
2. Hook up your test light or meter.
3.Turn the ignition to RUN. Do not start the engine.
4. Install the self test jumper. Notice if the IAC plunger retracts so there is a gap between the plunger and the pad.
5. The self test should start running KOEO (key on engine off) tests and outputting codes to the meter or test light. (your car doesn't have a check engine light)

To rerun the KOEO, turn off the ignition, wait 10 seconds, remove the jumper and start again at step 3.
You will have to do this several times to learn how to read the codes.

So  try this and get back to us and we will help you learn to read the codes.