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ignition control module?

2K views 2 replies 3 participants last post by  Two8tyThree 
#1 ·
How do i know if i have a defective control module in my HEI distributor? Ive been chasing down a problem with my 383.. some days it runs good.. some days not so well. I notice when i clamp my timing light on the plug wires, some are very irratic, some will not spark for almost 2 seconds at a time. I really cant think of anything else that would make the car run bad. Everything is brand new on the engine except for the distributor itself. I changed everything on it to msd parts such as cap rotor and ect, but the control module is stock.
 
#2 ·
stroker444 said:
How do i know if i have a defective control module in my HEI distributor? Ive been chasing down a problem with my 383.. some days it runs good.. some days not so well. I notice when i clamp my timing light on the plug wires, some are very irratic, some will not spark for almost 2 seconds at a time. I really cant think of anything else that would make the car run bad. Everything is brand new on the engine except for the distributor itself. I changed everything on it to msd parts such as cap rotor and ect, but the control module is stock.
Most parts stores have a tester they can plug the module into. They are a high failure item but usually they just die. First thing to check is make sure you have full battery voltage the the HEI plus terminal. You didnt say what kind of car it is in but the older cars had a resistor wire in the run circuit to drop the voltage. Your HEI will not be happy with that. A coil that is breaking down can also cause the issue you are seeing, unfortunatly without some expensive equipment they are hard to diagnose.
Also take a look at the pickup wires, make sure they are not cracked.
 
#3 ·
I agree with Chet. Check the pickup coil wires they usually crack at the the joint to the coil windings inside the insulation. They look fine but if you pull on the wires, the insulation will stretch. Also check to make sure you have the right electronic grease under the module do not use silicon or petroleum grease. If you did the module will be toast.
 
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