I'm working on my 93z28 with opti-spark system, It crank but it won't start.
It has fuel pressure and spark but no injector pulse. I check power and ground to the opti-spark distributor, it has 12.6v,a ground and two reference voltage, 4.8 volts from ECM to opti-spark. I also check for the high and low resolution signal with my snap on lab scope, it has a high resolution signal,but no low resolution signal from opti-spark. I already replaced ECM and opti -spark distributor and still won't start. Please help,i greatly appreciate if you all can help.

 

do you have any codes? what brand of opti are you using? anything but ac/delco or delphi is known to have problems.

 

First of all if the low res signal was actually gone it would have a code for it. With a paper clip you can get the code from a 93. Confirm it's there before going any further. If you indeed have a code for low res failure, that would explain why the injectors have no pulse. (I assume you already know this).

Next check the actual signal at the opti connection directly. If you indeed have power and reference at the opti and the signal is not coming from the opti connector, the opti is dead. BUT BUT BUT. There are many things that could appear wrong if it is done wrong.

 

Check the ignition coil, or ignition module. I had the problem twice, once where my car just died out while driving, and wouldnt start back up. Then also had a problem with my car stalling. Both problems were fixed by replacing the ignition coil, and its quite easy and cheap. Just look into it, I dont know how to check if its working or not.