I recently purchased a 94 Z28 6 speed that needed a little work. I towed the car home and after replacing the radiator took it out for a test drive. The car seemed to run great until it reached normal operating temperature at which point it started running rough. I did some surfing on the internet to find that this is a common problem with the Optispark so I ordered one from Summit and proceeded with the installation. I didn't find a keyway on the splined shaft and didn't have a problem installing without using force so long story short reassembled everything and started the car. It started immediately and ran fine for about 15-20 seconds before it started running rough again and cut off after about 45 seconds. At that point I was unable to start the car again. It turns over and sounds like its just so far out of time it simply won't start.

Did I miss something during the installation? does the shaft need to somehow align with something? Or do I have a problem with the ECM? Any help or direction is appreciated.

Ron

 

the opti can only go in 1 way there is a key way its a thick spline on the shaft

http://img291.imageshack.us/img291/5369/9394opti.jpg

 

So someone would have to use a bit of force to jam it in the wrong way? I see the thick spline on the old unit but it looks like it has a groove in it that's not as deep as the others. If I got lucky with the alignment since I didn't force it in what else could be wrong?

 

it would take a lot of force to misalign it probably a hammer

id get the car scanned for codes

 

Could be the ICM, wires, plugs, oxygen senors. All could make it run rough...but I don't believe to the point of the car not starting at all. Are you sure you have gas in it? I know it sounds stupid, but when I first got my car, I forgot to add gas and it wouldn't start. As far as it being out of time...I do believe the computer self corrects itself and puts in correct time.

 

ya theres no mechanical timing its all computer

 

the icm could make it not run at all. I would check the battery voltage, too. The car may turn over with a weak battery but may not have enough to run the electrical ignition components properly. I also check the plug and harness that goes to the opti. Then maybe test the injector circuits with a noid light. Though its not likely that all of them would go out its easy enough to check and it is possible. If you have no circuit to all of them its likely a pcm issue. also you said it ran fine with the old opti until it got up to temp, so i would check coolant temp sensor for that but it could be a seperate issue.

Also did the car throw an ses light on? if so have it scanned.

 

test your fuel pressure, 33 on the list here 4th Gen LT1 F-Body Tech Aids . check for spark. heres a few things you can do. look at 28 on that same list. and look here https://camaroforums.com/forum/lt1-l...t-start-65637/

 

I took everything apart again and with number 1 at TDC I pulled the cover off the optispark and made sure the rotor was in the correct position. Turns out that it can be installed in many different positions without forcing it in. I replaced the coolant temp sensors, TPS, sparkplugs, plug wires and coil, I haven't replaced the ICM or O2 sensors yet. The car starts now (full charge on the battery and plenty of gas), but will only idle. Checked fuel pressure and it's within range. I can get it up to about 1100 RPM but I noticed that the exhaust manifolds get red hot very quickly. I tried to pull out codes, but they don't flash on the 1994 and I don't have a scanner.

 

there should be a blank spot in the splines of the shaft that drives the opit. sure sounds like a plugged cat. need to get that taken car of then most likely you have or have had a rich condition so look for anything that would point to that.