I have 1994 lt1 under wot its missing and poping putting out black smoke, i tryed everything and problem is still there, changed pcm,icm,plugs,wires,cap,rotor,coil, fuel pressure is good and doesnt drop off. any ideas? no codes.

 

tune ???

 

Try unplugging the MAF, If it goes away either replace or clean your MAF

 

unplugged MAF problem still there.

 

well I been driving the car and now it seem to run good, until you sit and let the car get really warmed up then it starts running bad again.

 

"replaced the cap and rotor"? I had this same problem in my 94 LT1... I did everything that you have done....

The only thing that helped it was completly changing the Opti-spark... I went to a vented one for the 96'... been a while and dont remember all the details of the swap to a vented vice a non-vented.....

Then it helped even more when I got the Del-teq system with NGK plugs and MSD wires!!!!(I love USAA loans)

 

i guess it could be the opti but i dont see why it runs great until you let it set and warm up for 15mins??

 

well now the tack starts jumping when it starts missing.

 

How does it do at 3/4 throttle? My car runs the best at anything less then WOT. I know there are tons of posts on here about performance issues after the car warms up. There should be lots of info in the old ones.

 

yeah car runs fine at 3/4 throttle.

 

I had a problem similar to that, it was my o2 sensor plug, it melted on my header. sending false/bad signals to the computer under full throttle!

 

I know it doesn't address the issue in this thread, but the PCM doesn't get information from the O2's at WOT.

For the OP, have you logged/monitored the car to see how all the sensors are acting as the car gets warmer?

 

If your tach starts jumping then it is proly your opti, even though you replaced the cap and rotor it is the optical sensor that is bad.....

 

yeah all the #s look good, seems to be doing it less and less the more i drive it so i dont know we will see what happens.