HEI ignition module question (L98)
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
HEI ignition module question (L98)
Hi everyone,
I'm just curious - how do you know when (or if) the stock ignition module needs to be replaced? Is it a wear item that needs to be replaced with some frequency, or is it something that normally lasts the life of the car? How do you test one to see if it's gone or going bad?
Thanks very much in advance.
I'm just curious - how do you know when (or if) the stock ignition module needs to be replaced? Is it a wear item that needs to be replaced with some frequency, or is it something that normally lasts the life of the car? How do you test one to see if it's gone or going bad?
Thanks very much in advance.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Racer
Joined: May 2004
Posts: 295
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From: Newton NJ
Mine went two months ago on an 87 with 65,000 on the clock. It left me stranded on the interstate, it provided no warning. I would think about replacing it the next time your doing a cap or wire replacement.
Thread Starter
Drifting
Joined: May 2002
Posts: 1,581
Likes: 2
From: The Motor City
Originally Posted by adi4
It was Merle at EM that supplied me 
Did you notice any difference in the way the engine runs after you installed it? Better idle, smoother running, quicker starts, better mileage, etc...?
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Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
The spark control module is a power transistor switch that connects 12v to the spark coil primary and then rapidly switches off when the distributor pickup coil generates a pulse and the ECM conditions the timing of when to switch off. I do not see how an aftermarket module can do that job any better as it must also have a power transistor to do the switching exactly like the GM module!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Burning Brakes
Joined: Oct 2004
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From: Weymouth Dorset
Originally Posted by TheCorvetteKid
Very cool - thanks!
Did you notice any difference in the way the engine runs after you installed it? Better idle, smoother running, quicker starts, better mileage, etc...?
Did you notice any difference in the way the engine runs after you installed it? Better idle, smoother running, quicker starts, better mileage, etc...?
If there was any difference it was a smoother idle, but I changed it for peace of mind more than anything else .
.
Moderator Emeritus
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From: Maryville Tn
CI 5 thru 12 Veteran
St. Jude Donor '09 thru '23
NCM Sinkhole Donor
I replaced mine on my '85 when I bought it 3yrs ago. It was mainly for peace of mind because of the age of the car and the fact I was replacing the cap, rotor, and wires anyway. I'm glad I did because there wasn't that much grease under the module I replaced. It was only a matter of time before it cooked itself and left me stranded! 
Team Owner
Joined: Mar 2001
Posts: 54,124
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From: Cincinnati, Oh USA
It won't hurt, but I wouldn't. I drive everyday an 87 and several years ago at about 150k miles it was hard to start and it was the spark control module. If your engine runs fine, let keep on running fine!
Melting Slicks
Joined: Oct 2000
Posts: 3,426
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From: Heidelberg PA
Cruise-In V Veteran
Another indication that the module is on its way out -
I was getting a rpm variance similar to a miss right at 2100rpm, I could feel it and watch the tach jump.
With rpm lower or higher no miss, replaced module - gone.
I was getting a rpm variance similar to a miss right at 2100rpm, I could feel it and watch the tach jump.
With rpm lower or higher no miss, replaced module - gone.
