I just replaced my optispark 2 days ago, put longtubes on, and after having the car on jacks for a week, I was very anxious to hear it run. Well, after I put everything back together, I try to start the car, and nothing. It will crank all day
and not start. So I pulled a few plugs to check them and sure enough none of them were sparking, I tried about 5 plugs. Then I bought brand new plugs thinking I might have fouled them out from when the car broke down the first time, and no spark from the new plugs either. The opti install is very cut and dry, I put the new one on and after about 5-10 mins. of wiggling got it on the dowel pin and completely flush with the timing cover. Hooked it to the wiring harness and put all my boots back on. I did the coil continuity test and all my readings were perfect. I have an aftermarket coil that I really didnt need since my stock 1 worked fine, so I even put the stock coil back on and no luck. What else could there be? Surely not EVERY wire is bad since I have tryed all the wires for spark. Could it be the PCM?

Any input at all guys would be very much appreciated, this car has given me nothing but trouble since day 1, and I might begin to look around and sell it if I cant figure this out.

 

If it were the PCM, I think all you would hear is clicking. Whenever I change an opti, I start it while the waterpump and everything is off, just to make sure it runs.

 

Confirm output of the coil to the opti, On one side of the coil as well you should see pulses from the opti as it spins, check your grounds by the coil and pass side of the block. If you have steay voltage to the coil but no pulsing voltage your ign module may be bad. Also insure your opti is plugged in correctly.

The Opti can go on the wrong way so I wouldnt compltely rule that out. Although you should get at least some spark like that.

 

Well, its been a few days and car still wont start. I get no spark through the opti OR coil, so im guessing the problem is within the ICM. Going to replace it today and see if that fixes the problem.

 

If it's a spline drive opti, pull it and make sure it's in right. I just fixed one for a guy yesterday that had the same problem; he somehow got it together wrong.

Ryan

 

spline drive?

 

The 92-94 LT1s used a slpined shaft from the timing gear to the back of the opti to drive it, the newer optis are driven by the dowl pin in the camshaft, the 92-94 splined shaft driven optis were very easy to install incorrectly, but even installed incorrectly you would still have spark , but just at the wrong time.

http://shbox.com/1/93-94_opti.jpg

Picture courtesy of Shoebox's site.

http://shbox.com/1/4th_gen_tech1.html

Fixed my last statement, I had right instead of wrong in there.

 

If it could be installed far enough off, the rotor would not be near the correct spark plug when it is required to fire. Making it appear as though the spark where not occuring at the plug but the coil should still fire. However don't forget that if the spline were inserted incorrect, the reference signal from the 2 optical encoders would be wrong thus the trigger for the spark would be occuring at the wrong time as well.

 

same thing happened to me when I replaced my Opti..thought it all was installed correctly..hooked up right and all. The bolts for the Opti even went on without much trouble and it was flush against the timing cover. Car turned over and over and over...finally uninstalled and reinstalled the Opti and it worked. Its 9 times out of 10 just the shaft in the Opti not catching (not aligned properly). Would be nice if that were your fix eh? Good luck. Check, recheck, then check again before messing with the ignition systems of your LT1

 

Im on my 4th one. (Cheap a$$ autozone parts with lifetime warranty)

Anyway. Every time I have changed I have had a problem with the 4 pin wiring harness that plugs into the opti. Ive had to replace it once. Pull it loose and see if the connectors are all straight, sometimes mine get bent up pretty bad. Does it feal like it plugs in smooth and easily? This will give a no start and I have had problems with it every time.