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z24i ignition module problems


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Hey everybody, this site has a ton of good information on this topic but I haven't seen a thread regarding this particular problem with the ignition system. I know this forum covers a lot of older stuff I guess this is more of a shot in the dark to maybe get some advice. I have a z24i with a cas distributor, replaced coils, int and ex modules, cap and rotor. I've got good ground and 12v to both coils when the key is in the on position. It starts right up and idles great until the modules get so hot they quit working. I suspected bad coils but new ones haven't changed a thing. When I leave the key on and the plug wires unhooked from the distributor, no such heat occurs but as soon as I plug them in to the distributor they start to overheat. I have a new distributor but really don't want to mess with the timing, is it a better idea to start tracing wires back to the ecu or replace it all together?

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The CAS distributor doesn't really work the coils. The information from it is supplied to the ECU which computes the timing advance and powers the coils.


Can I assume the old 'modules' also got too hot and this is why they were replaced???

Were the old coils after market? or the originals?

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The truck was brought into a shop I was an apprentice at with no spark. After a cap and rotor was put in, it ran again but only for 10-20 miles or so then quit. The old modules looked corroded and damaged so they were assumed to be bad and replaced. The coils were replaced with orileys ones along with them by this shop. That's when this problem started. I have the stock modules and they look bad but its hard to tell if it was wear and tear or heat damage. The old coils put a lot more load on the modules, I've tested them against the rockauto ones I got once I bought the truck and they heat up way faster with old coils vs new. Like 20 seconds versus a minute or two of run time before I have to shut it off due to unsafe heat. I guess I must have been completing the cricut by plugging the wires into the distributor versus the signal from the cas actually causing them to heat up. 

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8 hours ago, Skifoo said:

 The old modules looked corroded and damaged so they were assumed to be bad and replaced. The coils were replaced with orileys ones along with them by this shop. That's when this problem started.


 Apprentice. Learn from this. When a problem arises, always ask yourself or the owner, what was the last thing done to the vehicle???? Problem started after coils and modules were replaced. Seems pretty obvious that wrong parts were installed or installed incorrectly. NEVER assume! NEVER replace just because they 'look' bad. NEVER throw away old parts. If you have the oil coils and modules put them back on.



NEVER replace more than one thing at a time.

NEVER assume a new part is in perfect running condition.

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I never said I was the one to do that work on the truck, I bought it because this shop couldn't get it running, the owner was done with it. I figured I could do better with some actual diag procedures. If I didn't know the difference between mechanic and parts replacer I wouldn't be here right now. I have the old parts, if I plug them in the truck does not start. I should have said the modules do not work instead of they looked bad. I've tested the resistance on my new coils and they are within haynes manual specifications, the old ones are not. Do you know of any other element that could cause the modules to heat up aside from a bad coil or being installed improperly? This truck also had plug wires put in, they are all in correct order but could that also be a culprit? I'm not going to pretend like I know everything so I'll check again tomorrow morning but these are pretty straightforward to hook up, the truck runs great the modules just get hot. 

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It wasn't that clear. Got you now.


With earlier EI ignitions the coil(s) are grounded by the ignition module to build the magnetic field in preparation of firing the spark plugs. However if the engine is not started within a fraction of a second, the module removes this ground so the coils don't over heat or run the battery down. As soon as the engine begins turning it resumes grounding the coil(s). It would seem that yours are 'on' all the time. 


Does your coil have a flat power transistor on it? Looks sort of like this... Or is that what you are calling the 'module'???





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