Girlski

Hello everyone,

I have a 99 cherokee 2wd 4.0 manual transmission.

I have an IAC code a pcm code (5v reference one)

At first it would idle between 500-800rpm sounding like it is going to die, then it will bump the rpms to 1100-1500 rpm for a few seconds then back down to the low rpms. When driving you have to play with the clutch and the gas to get the rpms high enough to where you can feel the jeep catching the shift. After a few mintes the jeep will drive normal like there is nothing wrong.

I removed the IAC , it was fully extended amd nasty, cleaned it up and cleaned the throttle body, reinstalled the iac and no change in issue. Replaced with a new iac and now im getting a an idle jumping between 2400-3000 rpms. Now when driving the jeep jumps to 3000 rpm when the clutch is depressed l. Once shifting the rpms jump down to 2000rpms and you can shift normally but it is at a higher idle. Just for ****s and giggles I swaped the IAC back out with another new one and im still having the same high idle.

Does anyone have any suggestions ?

Ive replaced the battery, changed out terminals (they were looking pretty sad and falling apart) I cleaned off major ground spots on the body and motor. I used up almost a whole can of starting fluid spray down tue engine while it was running to hear an idle jump amd cant find a spot where a vacuum leak could be comin from.

Ive tried looking for a pcm but it is challenging to find a pcm for a 99 manual transmission. The pcm that is in the jeep now looks to be a junkyard pcm. Would a pcm for an automatic give me these issues?

CCKen

The part number on your PCM should be 56041 488AC.


Now upgraded to 488AH.

Girlski

In all honesty if this was a newer model jeep I wouldnt ask this question but I can find a 98 jeep cherokee 4.0 2wd manual trans PCM looking at the specs between the two jeeps there is no difference between the two as far as air fuel ration and engine cylinder temp with the computers ability to do the mathematical calculations for proper ignition.

Will it make a difference if I get a 98 pcm vs. A 99?

EZEARL

.

CCKen

OP,


What are the two codes (numbers) you get?

Girlski

Im going to have to get back to you on the actual codes. I cant find my print outs for them.

I know the description was
IAC reading short to ground

No signal between pcm and tcm

I do remember seeing a torque converter code which is why im thinking who ever had the jeep before me got a pcm meant for an automatic tranmission jeep.

CCKen

I was wondering about the " pcm code (5v reference one)".


What is the part number on the side of your installed PCM?


Was your Jeep converted from auto to the manual transmission at some point?


Code numbers are needed.

Girlski

If it was converted I would have no idea. I am the third owner of the jeep, originally I called the dealer to see if they could tell me what pcm # I needed to be looking for, I gave them the vin and they didnt correct me by saying it was automatic. I had them verify for a manual transmission at the time.


#493ae is whats in there now

CCKen

493AE is for a 4.0, Auto transmission, California emissions.


Look at the white decal on the driver's side of the firewall and see if it says California Emissions.


In any case, 493AE is the wrong PCM.


You need that 488AC PCM if you have a Federal Emissions Jeep or a 489AC if you have a California Emissions Jeep.

CCKen

If you feel adventuresome, you could try a junk yard '98 PCM.


531AB - 4.0, Manual trans, Federal emissions


532AB - 4.0, Manual trans, California emissions


California emissions will have a Leak Detection Pump.

Girlski

Thanks for all the info
My suspicion was correct about the wrong pcm being in the jeep.

Do you know of any good sites to look for the pcm? I looked at 4 different sites and no luck ok the 488ac

EZEARL

Did you check here:
http://carcomputerexchange.com/jeep/...e/prod_90.html


The part numbers in stock are below:
56041488AC