Repeated ignition coil failure on 93

[jamot1]

I recently replaced the ignition coil on my 93 caprice 305 tbi with 202,000 on it thinking it died from old age (original coil)......

My replacement lasted about 1000 miles and died. My 3rd one lasted 3 starts and died. I heard an audible "click" when I turned the ignition to the "on" position from the coil before it died this time.

Does anyone have any idea what my problem is? It is definitely failing on start up... Could a worn ignition switch cause a surge or short at start up? No wiring schematics I've looked at shed any light for me.

Anyones help is greatly appreciated to help me get her back on the road!

[CD Smalley]

Wow you got me. How are you diagnosing that the coil is bad?

Are you sure it's not the ignition module?

[jamot1]

Yeah, it's got a lot of people, including some very experienced techs I've talked to.

I can replace the coil with another and it fires right up!........Until it fails again that is... I poured over more wiring diagrams today with no avail. One tech I talked to suggested the radio noise capacitor could be at fault, although I'm not sure it's a seperate piece from the ignition module....

One thing I did not do when I replaced the original ignition module(done during the original coil failure) is coat the underside with silicone/dielectric grease. I've since read this grease is essential in precluding heat build up and a possible short circuit or failure of the module... I'm going to put in another new module with the grease to see if this is the case.

It baffles me that the coil is failing during start attempts (all three have) and not driving down the road.

I'm going to put a multimeter on her this weekend and do some of the prescribed test....

Anyone who has any insight or knows anyone who knows someone....PPPPllease let me know!!!!

[CD Smalley]

I think you really need to check those coils to ensure they are the failed part following what's outlined in the FSM. I doubt that they are.

I think you are on the right track of replacing the ignition module with a new one and DO USE the grease. Without it you are headed for certain failure there.

[jamot1]

Yes, you are right. I'm going to put a multi meter on the failed coils to verify they in fact have failed, along with the ignition module and the pick up coil. Hmmm.... funny thing is, thinking back, there was no silicone on the module I replaced.

I initially did not mention, but I did put a new cap and rotor on, so no burned through rotor is causing the problem.

I did read last night, while searching the net, that a fellow mentioned that a pick up coil that is beginning to fail can have high resistance and cause a module or coil to fail.... I almost consider that a normal replacement part after 200k on the engine.

I am armed with a multi meter, new coils, new module with grease, and a new pick up coil, so hopefully I can find some answers in the next two days now that I have the time..... Will report back.

[studious03]

Can i get an update on this my 92 305 wont start....

[silicon212]

Yeah quit using those Wells coils from Autozone! :P