Hi guys. Just a question out there for all you LT1 gurus. What would cause my car to go through an opti at least every six months? Since early last June, I've had seven different optis in it so far, and it will be on an eigth as soon as I tear the car back apart and find my puller for the balencer/pulley. So far all since June this is what has been changed ignition wise: one pcm, two ICMs, four or five coils, two sets of plugs and wires, six optis, and I think that's about it. One of the distributors went due to waterpump failure, so a new GM waterpump was installed in December or January. Don't remember which. The vent lines have always been checked and they've always been clear. The opti harness is in great shape. What gives? Any guesses?

Oh, btw. It seems like it's always the optical part that goes. The cap and rotor are usually in great shape. The longest I've had a distributor on this car now is 11k miles, that's the one that's on it now.

 

The most common early failure cause is a cam dowel pin that is too long. You seem to have a stock cam, so it must be something else. Maybe you have some kind of voltage or grounding issue that is causing you to lose so many electrical parts. It's definitely not normal.

 

Thanks a million shoebox. Last fall I checked all the grounds I could find, cleaned them off well and everything. It didn't really seem to help much, but I may have missed something. Here's another odd clue for you, I forgot to mention this in the previous post. If you get the car out on a really dark night and open the hood with it running you can watch the coil arc to the square metal bracket that surrounds it. Just a faint blue glow. I don't know if the car is still doing it or not, but I'd imagine so since it done it since I owned it. This has happened with all the coils, distributors, plugs and wires, etc. It has never went away.

Is there any certain area or circuit that I should start checking first?

Again, thanks a million.

 

You stated that your vent lines are clear, but are they hooked up right?

From Shoebox's site:
http://shbox.com/ci/opti_vent.jpg

 

A constant arc between the coil and the metal on the front of the engine might be enough to damage the optical sensor electronics. But what you are describing seems to be more like a "corona" and not a heavy arc. Have you tried to isolate the coil from the bracket?

 

Well, I've isolated it from the bracket that holds it to the head, but it's arcing to the metal square thing around the coil itself. I don't really know how to describe it best, but the metal square around the coil itself has a corona between it and the plastic sides of the coil. Every time I've taken all the previous coils out and looked at them, there is very heavy carbon tracking on each of the plastic sides of the coil.

Thanks Injuneer, and I'm sorry I wasn't more specific. I just really don't know where to go with this car from here. It's been at several different shops and dealerships, because I figured I must be missing something, and it seems like every time it was, it just had parts thrown at it. I mean, the entire ignition system, except for wiring, from the opti to the computer to the icm and coil and plugs and wires have all been changed, a lot of those several times.

I don't know what to do with it, or where to start searching at this point. Thanks for all the help so far. Is there anything I should try? Any guesses?
Thanks again gentlemen. -J.Bird

 

Hate to say it, but you obviously have somekind of quirky electrical problem. And these are always a pain to track down. Get a good high quality multimeter. Like a Fluke 87 or better, and start checking every electrical parameter, particularly of the coil. Check volts in, check the ground, check resistance of the coils both primary and secondary. Check the coil wire connector and make sure it's not carboned up, sign that the coil to opti wire is not seated. Check the connection(soldering) of the internal wire of the coil. Pay particular attention to the coil grounds. It's grounded to the heads, heads to the block, block to the Neg. Bat. terminal. All should be near O ohms. I would go so far as to check the restistance of the spark plug wires and spark plugs. Make sure they are properly grounded and that they are not over gapped, Makes your coil work really hard. And don't forget about moisture, water or oil getting on the coil. In fact I would start by spraying the coil and that area down with WD40, while it running at night and see if the arcing goes away.
Good luck.

 

Thanks a million for all your help guys. I probably won't get to start on the car until after next weekend now, but I'll keep you updated. I just got word that my good friend (second cousins-we grew up together) got killed last night. He and one if not two more people were in a car or truck or something (don't know all the details yet) when they tried to beat a train in Saxton KY, right between Williamsburg, KY and Jellico, TN. Well, they didn't beat it. obvious outcome train>vehicle. He was killed and the other passenger or passengers of the vehicle were flown to Knoxville, TN and are in critical condition, so I'd imagine I'll be up in KY for a few days.

I'll be sure to keep you updated if I find anything. I do have a Helm service manual, but I haven't been able to find anything indicative as far as troubleshooting goes so far. Thanks for the clues on what to check, that will be the first places to start. I'm sure many of the parameters are in the service manual. Thanks a million again guys. --J.Bird

 

I keep going through optis. I got a hotcam out of a 96 and ground the dial off. Will this cause me to keep going through optis? My car is a 94(no dowel pin)