z28cam1993

No. I never had a chance to check the coil for spark. I had to move car so I just had towed straight to mechanic. I'm going To show him just what you said.

Injuneer

And you could have scanned it for codes yourself.... DTC 16 sets as soon as you turn the key to crank the engine.

You also indicated you tested for the Opti signal at the ICM. If you had the correct AC voltage on the white wire, you verified the PCM was receiving the low resolution pulse from the Opti.

z28cam1993

I did scan. Code 16 never set. Yes I had all correct voltage. So what else could it be so I don't spend money for no reason. I will show him what you said tom

z28cam1993

Loose ground? I'm totally stumped. remember when I said I looked for spark and when I ground the boot on plug one the engine started and I drove it.

Injuneer

I don't understand what you just said you did, and it wasn't real clear before.

Please explain.

z28cam1993

Sorry let me elaborate. I took the boot off of plug 1. I stuck a screwdriver in it and grounded to the engine block to test if they were spark. There seems to be spark at that moment because my friend got shocked and the car started and ran. So I put the book back on at tried to start the car And all it would don there seems to be spark at that moment because my friend got shocked and the car started and ran. So I put the book back on at tried to start is crank.

z28cam1993

Mechanic dug into car and tested the opti it's bad. He temp hooked up the new one and now there is spark. The bad opti is MSD

Injuneer

Just curious... how do you/he explain that you did a test and verified the Opti pulse signals were getting the the ICM? How do you/he explain that at no time did DTC 16 or DTC 36 set?

Is he basing this on looking at the pulse signal trace on a 'scope, as DelSoto suggested above?

The problem was apparently intermittent, since at one time you had spark and said you drove the car.

Knowing that the old Opti was an MSD would have been useful, because I have seen them produce a sporadic pulse signal. And that can be picked up from a Scan9495 data log.

Or is he possibly saying the rotor came loose, another common problem with the MSD?

z28cam1993

I haven't heard back from the shop yet so I cannot answer your questions but yes seems like was sporadic but I do remember coolant was leaking before sensor was changed right on to opti. Maybe that did it. Also I didn't know till the mechanic told me that is was an MSD opti.

z28cam1993

Ok a little update. Mechanic replaced opti with a brand new one. He says it now starts intermittently. Any idea what to check for now?