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Discussion Starter · #1 ·
Hello, I have an 88 I6 4.2 with MC 2100 and HEI.

I'm having an intermittent problem with my jeep stalling without warning while driving and then it'll crank but won't start again until it cools down a bit. I have had the ignition coil replaced, but that didn't fix it. The fuel pump has been replaced within the last year, so that shouldn't be the problem either.

My mechanic is recommending swapping out the ICM, but he says there is a chance that it might not be the problem. They've been driving it around and it hasn't stalled on them, so they can't seem to diagnose the exact issue.

I don't want to just throw parts at it, especially since I am paying for labor. He says it's going to cost me around $300 all said. Anyone have any other ideas?

I hate to be that guy, reporting back to my mechanic what I read on the internet, but I've already emptied every pocket, if you know what I mean.
 

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I believe it is mounted on the passenger side inner fender well so it should be easy to get to and a small socket set will unbolt it from the fender well and the plugs have little clips you need to disengage to unplug it. Reverse the procedure to install.
That is the same basic module Ford used in the 80s , my wife had a Ranger that would eat them so I bolted 2 of them on the fender so when one would quit she could plug the other in.
 

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Mowrangler is almost correct. It's under the overflow tank on the driver side fender well.You'll have to crawl under to see it.

Easy swap, 4 screws and 2 connectors. I think a module is about $45. Most parts stores can test yours if you take it in, but an intermittent problem may not show up. $300 for that job is robbery.

Another possibility is the pickup in the distributor. They do go bad, and if it's not sending a signal to the ICM it won't fire. Just something to keep in mind.

Edit: I didn't read very well. When you say HEI you mean GM style HEI or Team Rush? If it's a GM type the ICM is in the distributor.
 

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Discussion Starter · #9 ·
Edit: I didn't read very well. When you say HEI you mean GM style HEI or Team Rush? If it's a GM type the ICM is in the distributor.
It is the GM style HEI.

I'll try the ICM swap myself since they're pretty inexpensive. Even if that isn't it, it's one less thing that can fail in the future, right?
 

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GM HEI uses 12 volts and that's it?


12v to power the distributor, yes, but there is an ICM inside.

It is the GM style HEI.

I'll try the ICM swap myself since they're pretty inexpensive. Even if that isn't it, it's one less thing that can fail in the future, right?
It's an easy swap, but one word of advice. Use a quality thermal paste (think computer CPU heat sink) instead of the dielectric grease that comes with the module. It'll last much longer.
 

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Discussion Starter · #12 ·
Crap, looks like I just went and bought the wrong ICM. I was fairly ok with the idea of replacing the "stock" ICM located on the fender wall, but less inclined to take apart the distributor. It looks easy in the video but I know I'll **** it up. Also, if I just got this distributor installed less than a year ago, how is the ICM already messed up? If I replace it, will it fail again in less than a year because some other issue is causing them to die?
 

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Crap, looks like I just went and bought the wrong ICM. I was fairly ok with the idea of replacing the "stock" ICM located on the fender wall, but less inclined to take apart the distributor. It looks easy in the video but I know I'll **** it up. Also, if I just got this distributor installed less than a year ago, how is the ICM already messed up? If I replace it, will it fail again in less than a year because some other issue is causing them to die?
Firstly, if you can operate a screwdriver you can change the ICM. It is as easy as she made it look.

Since GM has quit producing the modules the quality has gone down. Heat can kill one quickly - as in a bad application of thermal grease. Semiconductors don't like heat.

Could be you have another issue, too. I tend to agree that the ICM is a likely culprit, but check the 12v feed to the dist and make sure those connections are good.
 

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12v to power the distributor, yes, but there is an ICM inside.
Yep I suppose you are right although I never really thought about it being that way. Regardless, all the previous posts (including yours :-D ) had the guy looking at the stock one which was totally backwards and had him out buying something totally useless.

OP, don't sweat working on the distributor before you actually pop the cap and see what's going on in there. Distributors aren't rocket science and you may be fearing something that's no big deal.
 

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Yep I suppose you are right although I never really thought about it being that way.
I wish it were simpler, but no. I've changed a bunch of them. One crapped out on me in the middle-of-nowhere-Kodiak-Alaska on my old FJ40.

Regardless, all the previous posts (including yours :-D ) had the guy looking at the stock one which was totally backwards and had him out buying something totally useless.
I almost got caught there. A lot of folks call the Team Rush upgrade an HEI, and that uses the stock ICM.
 

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Discussion Starter · #16 ·
Yep I suppose you are right although I never really thought about it being that way. Regardless, all the previous posts (including yours :-D ) had the guy looking at the stock one which was totally backwards and had him out buying something totally useless.

OP, don't sweat working on the distributor before you actually pop the cap and see what's going on in there. Distributors aren't rocket science and you may be fearing something that's no big deal.
I appreciate the help and the vote of confidence. Is this the correct part?

http://www.summitracing.com/parts/pro-66944c/overview/

I have the "blue cap" GM distributor.
 

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Unless you have something other than is what is listed for your Jeep I cant see $500 for an ICM. Labor shouldn't cost very much and in fact you could change it out yourself , it is just a couple of screws and 2 plug ins and the part is under $65.00.

http://www.autozone.com/ignition-tu...wd/1988/6-cylinders-c-4-2l-2bl/31688_90764_0/

I know you have got to have an Autozone nearby.
So I just got a lifted 93. Ran fine when I got it, today started it in cold and it starts fine but starts skipping A LOT when I push on gas pedal. NOW WHAT?
 
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