A little background: My 92' was serviced with a GM original Opti-Spark, Water Pump, Plugs, Wires, and Coil (The coil will be in question later) about 25,000 miles ago. The car has been very well maintained, the engine has never seen water, and my water pump is not leaking a drop.

Okay, I noticed every once in a great while (meaning once in every 5 or 6 rides), when I have been driving in very prolonged stop and go driving conditions (I usually cruise a car strip every weekend) Around 5000 RPM, the car would quickly, what I call break down for a split second, shift and all is fine. But it was EXTREMELY conditional, meaning I could have it happen, get off the throttle, and then accelerate to the same RPM again and it wouldn't happen. I know when my Opti-Spark went, it broke down in lower RPM's (around 4300 RPM) and it wasn't conditional, it was constant and the RPM's progressively got lower with every occurence.

On a hunch, I looked at the coil, and it seemed like an older coil (based on how dirty and old it looked compared to the rest of my engine compartment; I don't know if the dealership actually replaced it). When I removed the elctronic connections, they seemed fine, but when I removed the coil wire, the terminal was bright white, and the inside of the boot had a white powder. The metal contacts looked corroded white, almost like a spark plug when it is exposed to over extreme heat. There was also traces of dark (black) and white powder over some areas of the coil.

Question: Could the coil have been blasted by too much heat, cracked, and is now failing? (It is over the exhuast manifold) It couldn't be my Opti-Spark failing and the coil taking a hit on some back current, or could it? The car is excellent in all other RPM's and isn't temperature dependent. Any suggestions or comments are appreciated in advance.

Also: When it was damp Thursday (In MA) the car seemed to do it once or twice during a drive, but stopped when I got to some dry roads and had a chance to air out. I didn't think Opti-Sparks were effected like this, sounds more like a traditional coil short.

 

The coil is a problem with those things...

no question. I would expect it to be failing.

Get a factory stock GM coil. I do not recommend the hotter coils, mainly, cause I don't think they do any thing good for the cap and rotor.

The other culpret could be the coil wire itself. It rests on the opti, and motion can cause it to wear away.

at this point, miles is not the main factor, age is.

When you replace the coil, put a good shot of dielectric grease on it so the terminals don't corrode.

 

:iagree:

The coil will crap out at the higher rpm's if it is going bad. Since you have done the opti, replace both the coil and the coil driver.

 

Excellent. Thank You bogus and ittlfly for the prompt responses.

A new GM coil and driver will be on the way, along with a new coil wire just for good measures. It makes the most sense for a failing coil, and doesn't cost $300 for another Opti-Spark. Thanks for the help.

Take Care! :flag

 

I should have added that to be sure NOT to wipe the white grease off the mounting plate for the coil unless you have new to replace it. There is a big caution about it in the Helms....something to do with heat transfer.
Good luck. :seeya

 

Also in my case, with the same symptoms it was the coil wire rubbing on the water pump. Check that as well.