Start the car....Fry the HEI Module
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Joined: Oct 2001
Posts: 3,155
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From: Louisville, Ky
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
Start the car....Fry the HEI Module
Anyone have anything to suggest when I'm frying ignition modules with each start of the car almost?
I have a Pro Comp large cap HEI and have gone through three modules. I fired the car up 4 days ago and found I had a swiss cheesed radiator (How I don't know) so did not try to start it again until today when I got the new one installed. Would not start.
Knowing I had to replace the module to get it to start last time I went and bought another. Fired right up. Ran it for about 10 minutes and shut it off. Went to start it again 5 minutes later and no fire...
I have a Pro Comp large cap HEI and have gone through three modules. I fired the car up 4 days ago and found I had a swiss cheesed radiator (How I don't know) so did not try to start it again until today when I got the new one installed. Would not start.
Knowing I had to replace the module to get it to start last time I went and bought another. Fired right up. Ran it for about 10 minutes and shut it off. Went to start it again 5 minutes later and no fire...
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Joined: Mar 2006
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From: CALI
Car: 85' Trans Am !best car ever!
Engine: 305tpi 215hp LB9 two bolt,
Transmission: th-700r4
Axle/Gears: stock (3.27)
Re: Start the car....Fry the HEI Module
sounds like a grounded coil or pickupcoil or condensor. you didnt mention the module thermogrease under the module.? test the ohms on all three componants and pray one is bad. the coil and module are like buddies. if one goes bad the other will die soon after. lets just say you have a coil that fails when hot only and ruins your sweet module. you got warranty on the modules. shouldnt have to pay $$$.. and second. sounds to me its an ignition problem. you say you have a pro comp hei dizzy, would possibly the leads to the ECM match the same leads from a stock. Its got to be somthing sooo simple. Ive got a an ignition control module, two actually on hand, if you need one ill send it, BUT you should be able to claim the warranty. check your leads to ecm, test for codes. test the resistance of the coil and pick up coil, you may have a bad surge from the alternator (doubt it).
Last edited by transam85dudeman; Aug 30, 2009 at 11:45 PM.
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From: MN
Car: 85 SC, 86 Berlinetta
Engine: V6, V8
Transmission: 700r4, 700r4
Re: Start the car....Fry the HEI Module
Don't know if it matters but did you double check the engine ground to the firewall?
Thread Starter
Supreme Member
Joined: Oct 2001
Posts: 3,155
Likes: 2
From: Louisville, Ky
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
Re: Start the car....Fry the HEI Module
sounds like a grounded coil or pickupcoil or condensor. you didnt mention the module thermogrease under the module.? test the ohms on all three componants and pray one is bad. the coil and module are like buddies. if one goes bad the other will die soon after. lets just say you have a coil that fails when hot only and ruins your sweet module. you got warranty on the modules. shouldnt have to pay $$$.. and second. sounds to me its an ignition problem. you say you have a pro comp hei dizzy, would possibly the leads to the ECM match the same leads from a stock. Its got to be somthing sooo simple. Ive got a an ignition control module, two actually on hand, if you need one ill send it, BUT you should be able to claim the warranty. check your leads to ecm, test for codes. test the resistance of the coil and pick up coil, you may have a bad surge from the alternator (doubt it).
[you can't test voltage in the engine bay when running because the digital meter goes crazy from some sort of interference!]
I have the engine grounded to the framerail with a 4ga strap, engine grounded directly to the relocated battery in the trunk, and battery grounded to the rear framerail with 1/0 welding lead so I think I have that covered but I may add another fro mthe motor to the firewall for good measure. Oh, I also have an extra ground strap from the alt case to the engine.
Thread Starter
Supreme Member
Joined: Oct 2001
Posts: 3,155
Likes: 2
From: Louisville, Ky
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
Re: Start the car....Fry the HEI Module
Update:
Removed ignition module and re-installed it. Car fired up fine, WTF. Alt output only 12.46v (at battery and alternator) and not increasing with RPM. 12.18v with fan running.
Shut the motor off via my kill switch and no voltage spike. Just rose back up to 12.5v.
Now I expected it not to start again since the motor got hot; tried and it started again. Will try in another 15 minutes to see what happens.
Any freakin' ideas here???
Removed ignition module and re-installed it. Car fired up fine, WTF. Alt output only 12.46v (at battery and alternator) and not increasing with RPM. 12.18v with fan running.
Shut the motor off via my kill switch and no voltage spike. Just rose back up to 12.5v.
Now I expected it not to start again since the motor got hot; tried and it started again. Will try in another 15 minutes to see what happens.
Any freakin' ideas here???
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Joined: Nov 2006
Posts: 248
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From: Tx
Car: 86 Camaro
Engine: 305
Transmission: 700r4
Axle/Gears: 3.73
Re: Start the car....Fry the HEI Module
Napa part # RR231. Capacitor terminal block assy. Basically the condenser and your connectors are all made into one assembly. I'm betting something's jacked with your contacts and when you wiggle it/unplug plug it back in, it's making connection again.
Dan
Dan
Thread Starter
Supreme Member
Joined: Oct 2001
Posts: 3,155
Likes: 2
From: Louisville, Ky
Car: 1991 Z28
Engine: 383
Transmission: T-5
Axle/Gears: 3.08 10 Bolt
Re: Start the car....Fry the HEI Module
Thanks Dan, that's a big help. I'm chasing all sorts of problems but that puts a little light into the no spark issue.
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