the car is a 1994 Z with a4/ 3500 stall 230/236 383 short w/ LT4 heads /intake / valvetrain.

Ok, here is what I know. The car is running a little weaker than it should be and shaking a bit more than it should be. I dediced Id look for a weak cyl. with my infraed ther momater. sure enough, when the car is fully heated up all but 1& 6 primaries read 650-700 but the 1 and 6 primaries read 350-400 I dont have an accurate enough tach to do a cyl balance test but im sure tese are the problem cyls.

Here is what I have done...
Replaced plug wire with known good plug wire. no change
Swapped 1 &2 and 6 & 8 fuel injectors. problem still on 1 &6
Used a spark tester, It hit 25k volts no problem.
Visually inspected plugs, they look fine and are gapped right and still have the platnum discs.
I think Im going to get 2 new plugs and try em anyway, wouldn't hurt to have spares around for testing....
what else is left? computer problem with injectors? I doubt it.
Could the opti couse this? if so why would it pass the spark test?
or lastly, mechanical/. valves? bad grind?

any other tests that i could do?
I gotta dyno tune this thing monday so please give me some suggestions.

 

Not really sure what to tell you. Try the new plugs. Hell, try 8 new plugs.
Could be the opti. Don't know much about spark tests. And mechanical stuff isn't my expertise....come to think of it nothing is.
Try some new plugs and see what happens.

 

plugs didnt help. I think its the rings or valves.

 

Do a compression test on the motor. It will tell you if you have any bad valves or bad rings right away. But I am gonna have to lean towards a bad opti. My brother has a 94 Z28 too, He came over one night and asked me to look at his car. He said it seemed like a couple of cylinders where not firing. I drove it and it seemed sluggish and I could feel like a couple of cylinders where not firing. I tried new plugs and it didnt work so I took off the opti and replaced it with another one I had in my garage. It was fixed. I took his old Opti apart to see what it looked like and what a mess it was. Full of Crud and RUST. Damn GM for not Venting the early models. So its been about 2 yrs and the symptoms are acting up again. This time I am changing it over to the 95 newer style.

 

Let me throw in my 2 cents, I would think that if you are getting
spark on the two wires on the dead cylinders that the opti is ok,

Why do you doubt that the injector system could not be at fault ?

I would install a "Noid" on the offending cylinders injectors to
check that the ecm is or not firing the the two fuel injectors, I
would not rule that out yet.

Dave B