No Spark ?
 

Thanks in advance…I am very new to an LT1 so please forgive me if I have missed something obvious in this but this thing is driving me nuts. Car is a 96

I have no spark coming from the coil

New parts: Optispark, ICM, Coil, Plugs and Wires

I have no spark coming from the coil, I have the proper readings at the opti harness and ICM connector and I have power at the red on coil connector for power…what should I be seeing on the green wire at the coil?

I replaced the ICM twice and coil twice just to be sure…are there any other sensors that could cause a no start/no spark condition? I have fuel at the injectors and good compression

Re: No Spark ?
 

When you are cranking the engine, does the tach needle move up about 200 RPM?

Did you test per Shoebox's guide:

http://shbox.com/1/4th_gen_tech2.html#opti_test

Re: No Spark ?
 

yes I tested using that guide and no I don’t believe the tach goes above 200RPM when cranking…not recently I’ve been testing by spinning the opti instead of cranking and continuing to ruin batteries

Re: No Spark ?
 

So you have no 5 volt pulses on the Opti signal wires (pin A - red/black; pin B - purple-white) when spinning the Opti drive?

And you verified that the PCM is supplying the 12 volts required to power the Opti on pin C- red? And supplying the 5 volt reference on the signal wires when measured to pin D - pink/black? That's what the Shoebox test verifies.

When the Opti is off the engine try running a ground wire from the Opti metal case to the block. I'm not sure where the ground is for the 12 volt power supply.

What brand is the Opti? Not unusual for the cheap Chinese rip-offs to be dead right out of the box.

Re: No Spark ?
 

I have the correct readings at the opti harness and I also have correct readings at the ICM connector…the opti is a summit racing opti

Re: No Spark ?
 

You have 1-4 volts AC on the white wire from the PCM to the ICM (pin B) while cranking the engine?

If so, you have contradictory results. If there are no 5 volt square wave low resolution pulses from the Opti to the PCM, there can’t be any pulses on the white wire to the ICM. The PCM can’t time the spark unless it has the low res cam position signal from the Opti.

Re: No Spark ?
 

Perhaps you’re mixing threads up I never said I didn’t have the 5v at the opti harness I do have the correct readings according to the above mentioned testing procedure

Re: No Spark ?
 

Then read the signal coming from the Opti with a volt meter, as you spin it. It should be switching between 0 and 5 volts DC.

I guess I misread post #5. My apologies.

Re: No Spark ?
 

It doesn't have to rise ABOVE 200 RPM, that is just typical. The question is does it rise up at all.

Re: No Spark ?
 

I guess “move up ABOUT 200 RPM” wasn’t crystal clear. :) Plus he hasn’t signed back in since post #7……

Re: No Spark ?
 

My apologies honeymoon week in Tennessee! When cranking the tach does move and it does stay right around the 200RPM mark

Re: No Spark ?
 

OK that means you OptiSpark distributor is not dead and is outputting normal signals (to some extent)

Re: No Spark ?
 

Yes and I have signal at the ICM and also all other proper voltage (system voltage at A and D and ground at C)

Thats what has me wondering if there is something else perhaps some sort of sensor that would possibly cut spark?

Re: No Spark ?
 

I should point out that the 200 RPM test just verifies the internal operation of the distributor but not the ICM. Where are you measuring the spark? Coil output? Have you checked the coil connector?
If the tach moves up, no sensor is shutting that down.

Re: No Spark ?
 

Thank you for the information regarding the tach movement. I am not seeing any spark from the coil...the coil connector I have 12V power coming in at the connector and I also have voltage at the green wire at the ICM connector while coil connector is plugged in.