I'm pretty sure I have a bad distributor on my hands, but I wanted to run it by everyone here for a "second opinion". Back story: after 383 build I was running down the highway doing some calibrating and the engine died and would not recrank. I start the diagnosis and notice there is no spark at the cylinders but the coil is sparking. There is good continuity on the opti harness from the ECM, through the connecter near the passenger side valve cover, and on through to the opti itself. I have voltage on both 12V wires at the ICM as well as a good ground. The white wire at the ICM does not have 1-4VAC on it when cranking. For a second I got 200mv but that soon disappeared. It does have good continuity back to the ECM.

I'm calling this a bad opti. Concur?

 

You're making this far more complicated then it has to be. If you have spark at the coil but not at the plugs (need to check more than just 1). Then the problem is the high voltage side of the opti. Assuming plugs and wires are not the cause.

Also if you do have spark at the coil but don't seem to find the 1-4 VAC then your measurement method is wrong. Why? If the 1-4 VAC signal were not there, the coil would not be making spark.

You need to confirm the spark is not getting to all the plugs. I like to check 2 plugs on each side. 1 and 7 and then 2 and 8. I use either an inline spark checker or an inductive timing light.

If you know the plugs and wires are good, it's time to remove the cap and rotor. Chances are good the contacts in the cap will look like they have snow on them. Or the rotor fell off. But stop over analyzing the problem.

 

Excellent point. I suppose it never hurts to be thorough, but work for the sake of work is foolish. I wonder why I wasn't seeing the 1-4VAC on the white wire? I was using a known good multimeter on the "AC" scale and putting the positive side to the white wire and the negative side to ground. I saw nothing while cranking. I did check two separate plugs and saw no spark.

 

When you get the cap off the Opti, you'll be able to see if there is a problem. If you lose the high or low resolution pulses generated in the Opti, you should get a code.

WD

 

No codes. It stalled immediately with no warning signs. I'm almost hoping the distributor is bad. I don't want to have to start chasing wiring issues.

 

Like Speedy said, if the coil is producing spark and the plugs aren't, it's the cap/rotor... not your wiring.

Unless, of course, it's you plug wires!

Or plugs.

 

FYI, the rotor exploded. WTF? I'll get some opti carnage pics up soon. Its a good things I checked the wiring, even if I didn't have to. I had a ground wire that was hanging by a thread from its ring terminal. Thanks for the assistance everyone.

 

What brand was the Opti?

 

Delco. I bought it from a board member here who claimed that it was only run on the dyno for less than half an hour. He had a good rep as a seller and the pics made the claim look legit. I'm questioning whether it was an accurate claim now. I guess that's what I get for trying to save a few bucks. Lesson: when you've already spent thousands on a stroker build, what's another $50 to do it right?

 

Thanks for the replyto my post. I may have the same rotor failure with an Accel opti. I'll confirm in a day or so.