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Discussion Starter #1
i got a 4.2 motor in my cj5 and i have replaced the ICM every 3 months. dose anyone have any clue as of wat would cause them to keep going out like this. i have tryed looking and cant find anything on wat woulld do this. im not very handy with electical but i do know sum things and can figuer it out if someone points me in the right direction so any help would b nice.
 

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When you say ICM you mean ignition control module? Small grey box mounted on the fender?

If so, ditch it and the old canister coil and switch to an HEI ignition. When I did, the performance improved, and the system hasn't given me any trouble since then. I paid 100$ for mine, totally worth it.
 

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I bought mine at 4wd.com. Search for HEI and it will come up.

To install it, you remove your distributor and install the new one. Then you cut one 12V power wire currently going to your ICM (a big red one if I remember) and put a spade connector on the end and plug that one wire onto the new coil. I think you need new wires as well, but 4wd sells the wires with the distributor on page 2 of the HEI stuff. The install is really easy, took me about 2 hours going slowly. I loved having less crap in the engine bay.

Take a look at the instructions I found below, sounds like what I did.
http://www.crtperformance.com/html/258_hei_instr_.html
 

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Discussion Starter #5 (Edited)
hey man thanks. sounds prity simple and forsure way better that the stupid system that in there now. and ya im with ya on getin as little crap in the bay as possible. the only other question i got is that in the directions it mentions the ICM with only 2 plugs on it. i got the CA smog system that has 3 puls into the box. dose that make a difference?
 

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Might be worth taking a google search to see what the third plug does. If you need to keep your smog equipment for exhaust tests, you may want to keep it.

I think most bypass the smog stuff anyway. You may want to look up the "Nutter bypass", I think this cuts out the smog stuff and the third plug.
 

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Discussion Starter #7
ok i aint gota do the smog test unless i sell the jeep and that aint guna happen unless its goin out in a pile of parts form. but ya il check that out. thanks for all the help man.
 

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you could get an msd ignition but if you do get the offroad model, i dont think the other models hold up to water,dust,and vibration that well, i had one of the red msd boxes and it died one hour after i sold the jeep
 

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Discussion Starter #9
my buddy put a msd system in his jeep and has the heavy duty off roed igniton box and he has more problems with that than i do with the ICM. idk if he installed it wrong or wat but wachin im break down every time he drives it makes me turn away for goin that way
 

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The California spec box from '81 and '82 has a yellow colored strain relief where the wires go into the module, with three wire sets. The extra wire is for the ECU controlled timing connection on these models. The normal 2 wire set box has a blue strain relief.

There is a conversion called the "Nutter Bypass" that eliminates the timing control from the ECU. You can google it to find out more about it. It would allow the use of the more common blue strain relief box.

The MSD boxes are easily adapted to the Motorcraft distributor. They sell an adapter connector to mate the box to the stock distributor. This setup would bypass all the stock ECU timing controls.

A common cause of the Motorcraft box failure is a poor ground to the module. The factory setup grounds through the Black wire that connects to the distributor, the ground path in the distributor is through the moving advance plate. :homer:. A good fix is to splice the black distributor wire directly to the main engine ground at the dipstick tube hold down,(Six Cylinder) or where the battery ground cable connects to the block.

Verify that all of the ignition control module and distributor connections are corrosion free, repair connectors are available from Standard Motor Products.

Hope this helps!
 

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You may need to address the root of the problem first...

Before putting in another ignition module or switching to HEI (which is a very good idea, BTW), you should check to ensure your voltage is within spec (have someone rev the engine and make sure a voltmeter reads even and doesn't get above 14.4V).

If your voltage regulator is going south, it makes a lot of sense to check this or you could just end up blowing your next module.

If your voltage looks fine: like Marty SoCal said: it's likely the ground.


HTH,
Jake
 

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Discussion Starter #12
me and my buddy went throught my whole wire harness to look for burnt wires, breaks, bad connections, and all that fun stuff. didnt find anything. wen checked the volts and they run at 14.3 volts all te time. my alt has a built in voltager regulaor and its all working good so im thinkin its the ground. guna try that and c if that fixes the problem. also if i wer to put in a HEI ignition in and run the nutter bypass that would compleatly eliminate the ICM box right? im also shootin for less wires under the hood.
 

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The nutter bypass should get rid of the third plug, and the HEI will get rid of the ICM, and your old canister coil. It also gets rid of 5 wires crossing over the whole engine bay. I loved ripping that crap out of the bay.
 

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Discussion Starter #14
ya man im not guna lie that sounds like a plan to me. make things simpler and cleaner lookin under the hood.thanks everyone for the help and ideas.
 
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