Idle Control Motor for 87 2.5

[streetjeep2.5]

Mine is kind of "gerry rigged". Can't find anything on the internet as a replacement. What have you guys done in the way of fixing or eliminating?

[Pete M]

tried autozone? napa?

[streetjeep2.5]

Yep. Got Idle Air Control Valve for a 4.0, but not the Idle Control Motor for a 2.5. Probably just gut the puppy and let it work like the old carbs did.

[Pete M]

seems there is yet another item on our trucks that's GM in origin.

 

http://www.autozone.com/autozone/access ... ing=search

[streetjeep2.5]

seems there is yet another item on our trucks that's GM in origin.

 

http://www.autozone.com/autozone/access ... ing=search

 

this is 4.0, me thinks. Me be 2.5. It's origin is lost in the past and is now part of antiquity. :roll:

[Pete M]

got a photo of a 2.5 one? I don't yet have a 2.5 MJ.

[streetjeep2.5]

got a photo of a 2.5 one? I don't yet have a 2.5 MJ.

here ya go! The orange and white pieces are my gerryriging!

 

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It is on the Throttle Body where the throttle cable hooks up, and works like the idle adjustment screw did for a carb, but instead the gears inside the ICM let it down to idle slower than instant.

[88SporTruck]

The IAC on my 88 2.5 looks exactly like the IAC off my wifes old 3.9 Dakota. the plug is different tho.

 

I'm still trying to find a way to mount the Dak motor to the Comanche IAC body.

[streetjeep2.5]

This isn't an IAC if by it you mean Idle Air Control. Its called ISA Motor, or Idle Speed Adjustment. It works electrically from the computer the way the fast idle cam did on carbs.

[airspeed]

ISA or ISC (idle speed control) in my manual. I would go to the Pull-n-Save and find one on a 2.5 MJ/XJ. You can disassemble it and clean it up. There are a couple brushes and springs that fall out and (3) different gears, at first it looks complicated but if you study the assembly it will only go back together one way. The key is to study and note the disassembly process.

 

What a difference that made in the cold start cycle for my 2.5!!

[streetjeep2.5]

Yea, my problem was I got a rebuild kit a few years ago, and it was not exactly right. So I cleaned and reassembled and it hasn't worked right since.

I live so far away from any decent yards, so I am gonna put a request out in "classified".

[Cheech]

Not meaning to hijack this thread, but is there a way to test this component? Is there a way to test if the ISA is defective or if the problem lies elsewhere?

[Cheech]

I should also add, that I ask this because the one in my 86 does not work at all, everything is fine once it warms up, but when its cold you have to put something onto the throttle to keep the rpms up.

[Pete M]

the iac is operating all the time. if it was completely bad, I'd kinda expect issues after it warmed up too. :dunno: might be something like a vacuum leak that's sealing itself once it gets warm, or a faulty egr valve.

[Cheech]

But that little motor is electric right? It never seems to move and open the throttle like it should for cold starting. It actually never moves at all. :D

[Pete M]

I may be way off base here since I've not personally opened one up, but I don't believe it moves the throttle body plate at all. I think it opens and closes a small bypass hole to tweak the idle speed. :dunno:

[Cheech]

Lol, Thats alright. :cheers: It actually does move the plate open a bit. I have a picture here somewhere, I'll try and find it.

[Cheech]

Well, I managed to lose all the pictures I took when I pulled my engine out. I will take some in the morning for sure and post them here. :thumbsup:

[streetjeep2.5]

The electric motor turns the gears to increase or decrease idle speed depending on what the computer understands as operating temperature. It does not tweak air but does operate the throttle itself to raise and lower idle.

Again, kinda like the old spring loaded or electric chokes on a carb that worked according to the temperature of the engine.

Of course, some of you young wippersnappers may be saying, "carb?" or "spring loaded fast idle control?" Yep! Great technology that replaced the choke/fast idle cable you operated from the dash board to keep your engine from dying until it warmed up! Back then there was no "start", "put in gear", go". It was "start", "feather the throttle for a minute or two while you sat in a cold car and let the engine warm up enough to not stall and die", and then "went back inside to warm up while the engine warmed up," and then you "carefully accelerated so it would not sputter and die in really cold weather" because if it died you would probably flood the engine trying to start it again and then you held the gas pedal to the floor and cranked it over until it went "sputter, sputtersputter, hack, cough, cough, kinda run, run, varoom", and then go again! Oh, yea, feather it again! BTW, "feather" means be "REALLY LIGHTLY push up and down" on the gas pedal. Ah, the good old days!

[Vintage]

It was "start", "feather the throttle for a minute or two while you sat in a cold car and let the engine warm up enough to not stall and die", and then "went back inside to warm up while the engine warmed up," and then you "carefully accelerated so it would not sputter and die in really cold weather" because if it died you would probably flood the engine trying to start it again and then you held the gas pedal to the floor and cranked it over until it went "sputter, sputtersputter, hack, cough, cough, kinda run, run, varoom", and then go again! Oh, yea, feather it again!

Hey, my daily routine!

 

My '86 2.5 won't start or just barely stays running (when cold) without some throttle. Could this (possibly) be my problem?

[airspeed]

Now I'm getting confused, I'm looking in my 87 Cherokee FSM under 2.5 TBI. Under "throttle body" removal they say disconnet the wire harness from the ISC motor. That illustration matches what I have under my hood. A few pages in they start talking about the ISA motor removal and installation. What is the differance between ISC and ISA?

[utah_redneck]

ISA (Idle Speed Actuator), IAC (Idle Air Control), and whatever else there is are PRETTY much the same thing, they all compensate Idle RPM's to a certain extent. For the 2.5L TBI this part is called a ISA, I have found that AutoZone doesn't offer this part as they say it's a "DEALER" part. If you have idle issues this may be part of your problem...Part, but not nessasarily the whole problem. If you have someone watch the ISA and one start the motor you might see it move the throttle cam. The computer is the ultimate factor in how much and when this works based upon sensor inputs such as the coolant temp switch & sensor (should have both), air intake sensor, O2 sensor, crank sensor and throttle position sensor. If all of the sensors are tested to be good and the ISA works, there could be idle issues relating to the fuel system, vacumn leaks, and possibly ignition (least likely). I have had similar problems, but they are deeper than just a simple fix. Hope this helps clearify.

 

 

"airspeed"

ISA controls the throttle cam....

ISC is a different term for ISA.

IAC is a solenoid that helps regulate the amount of airflow beyond what the throttle plate does to "choke" in order to help with cold starts.

[airspeed]

Here is the electrical schematic for the (ISACM) Idle Speed Activator Control Motor.

[Cheech]

Hey Pete, here are the pics of the actuator on my 86 2.5. The plunger moves in and out (or it should anyways, lol) to adjust idle speed.

 

 

 

 

[airspeed]

When looking at the photos I see a hex on the end of that plunger, can it be threaded out to bump the idle up a bit?