Is it possible? Is a visual good enough? Just replace the cap and rotor with an MSD unit or get a completely new GM opti and not take chances?

Mine only has 4K on it, but the motor had idled erraticly and had a 4800 rpm miss on WOT on occasion before I pulled it. I'd be nice to know the condition of mine for sure either way...

 

 

It's possible, but is it practical?

Using an adjustable power supply to create +5 volts and an oscilloscope to detect the low-res and high-res output signals, you can turn the Opti-Spark shaft by hand and see the pulses.

But, this does not test the high-voltage side of the Opti-Spark, only the signal generation side.


Tom Piper

 

This is a tough decision with only 4 thousand miles on it, but if it was mine I would replace it. (complete opti) A cap and rotor will run about $150.00 and a complete opti will run a little over $200.00 or so.

 

Thanks Tom. Before the motor was pulled from the car (before it was totalled at least) we troublesooted the idle problem. We confirmed spark to each plug, and there were no error codes in the ECM. The ECM was reprogrammed by madwolf, but that should not have effected the ECM's ability to log codes would it? I agree without checking the high voltage output of the opti I'll never know for sure if it's the culprit of my problems.

I'm beginning to lean towards a new opti, geez at this point what's another $200. I'd hate to get this thing all back together and find it's bad...

 

I replaced my opti about 6 months ago with a new GM unit. Mine was in the car and I had to think about it for awhile before tearing into it. Erratic miss. After I installed the new one (runs great!), I tore the old one apart just to see what all the fuss was about.

Probably more written about this distributor than anything else ever made. My problem was the tiny screws holding the rotor...one had backed off and caused the "ear" of the other side of the rotor to break, allowing the rotor to wobble.

Can it be bench tested. Probably for visual and mechanical issues like bearing wear, carbon tracking and broken parts. The electronic scope thing is beyond my abilities. If engine is out of the car, I would certainly spend a few minutes and pull the opti apart...if only to satisfy your curiosity about spending the money for a new one.

 

When I removed my opti with 95000 on it to the best of my knowledge I saw nothing wrong. Cap was clean, no carbon tracking, 8 contacts very nice shape, rotor attached solid and the only ware was some darkness/arking at end of rotor which looked OK to me for that kind of mileage.

The other side with the optical section looked alright, just a little rust on the inside of the housing but wheel was fine. Expected to see more of something and can’t explain why I didn’t. When I replaced it the problem did seem to go away.

 

Definitely take it all the way apart and inspect for stuff like loose screws, optical wheel damage, debris or buildup on the optical sensor, etc. Any of these issues could explain your problem or confirm the Opti is the 'guilty party'. Adding a new cap and rotor should eliminate any high voltage problems that would have been attributed to the Opti. From what I have heard, the optical sensor (made by Mitsubishi) is supposed to be a fairly hearty unit that usually outlasts the rest of the Opti's components. Other than the relationship between the optical sensor and the delicate wheel, the inside workings of the Opti are pretty simple.
I am in the process of putting mine back together right now, using a new GM Opti (vented) with the MSD cap and rotor. I found out that the plastic 'middle' cover that comes with the MSD kit is TOO TALL and the rotor will RUB against it when assembled with the supplied O-rings. If I use the GM cover with its own attached seals, the rotor has good clearance and reassembly is normal.
So be WARNED, use JUST the CAP, ROTOR, and 4 cover screws from the MSD kit, and reuse everything else from the GM unit.
I still have the NEW GM cap and rotor of off this Opti, if you need them.