A friend of mine just changed the ignition coil, cap & rotor, spark plug wires, and spark plugs on a 93 Z28 to correct a high rpm misfire found during a dyno session. MSD components were used on everything except the plugs. Now that everything is back together, the engine cranks with great difficulty and detonates even under light acceleration. It sounds like the timing is too far advanced, but I think the opti spark distributor can only be installed one way as it relates to ignition timing. Any ideas?

 

it can be installed incorectly, especially the non vented ones

first make sure all the wires are on right

 

All of the wires are installed correctly. The engine idles & revs under no load without problems. There are no misfires and no SES light.

It acts like the timing is too far advanced - difficulty cranking and detonation under load at anything over 1/4 throttle. These problems did not begin until the parts were changed.

The distributor shaft has a flat space in the splines where it engages the cam gear, so how can the timing be advanced?

 

ttt

 

i think it is your opti spark

 

OH. OK.

REALLY?

GOOD GUESS!!!!!!!!!!!12222

 

ya rly.

 

so what did it end up being?

 

I know this is several months ago, but he never really was able to pinpoint the problem. It acted like the distributor was off 1 tooth, but the early design with the splined shaft will only go on one way. If it is misaligned, the splines don't line up and it holds the distributor away from the front cover. I have personally checked their installation and it is quite obvious when the splines are aligned correctly. From my research, it seems that the second design with the "clover leaf" pattern is easily misaligned. This is simply not the case on this installation.

The only idea we have is to replace the entire distributor as maybe the optical portion has some kind of problem. At the time this repair was attempted, MSD hadn't released their distributor assembly. I don't know why it is taking them so long since they have advertised it in magazines since late 2005. Since this car isn't used for daily transportation, my friend decided to wait on the MSD units to be released. He was pretty frustrated about the whole deal.

 

Doubt it since the problem got worse AFTER the cap and rotor where changed but no one said the back half was changed. If that were the case, it is easy to test.

 

I just replaced my OPTI It can only be installed one way because of the flat spot on the drive shaft. I would look at the plug wires esp where they pass behind the pulley on the passenger side. there is very little clearence there the wires have to be in the looms. NEW dosn't mean good. Irecently dissembled a AC Delco OPTI and found that they use Mitishubuti (*** parts) for the sensors. You wonder why GM has problems!

 

What's wrong with *** parts? I dont think the engineers would have choose to use it if they could make a better part. I dont think that's the source of GM problems.