need help with zr1

[jamieszr1]

91 zr1 car seems to run fine with key on or off but when it gets up to temp it seems to act like it is running on 7 cylinders, i did a fuel pressure check i have 40psi at idle and running down the road at wot it goes from 45 to 50 psi, so im thinking maybe o2 sensor , injectors or maybe someone elses idea

 

[jhong321]

i had the same thing happen to me a while back. after changing the following parts fuel pumps, coils, injectors, i finally took it to this one guy who was trained on the lt5 motors and he found out it was a sprak plug that was arking from the side. (all the spark plug where new at the time) he change the one plug and it was fine after that. i looked at the bad plug and could not even tell it was bad except for a very small thin line in it(looked like blk pen mark about 1/8 inch long). hopfully this might help you

 

[Rob]

Have you run a vacuum check on the secondary port vacuum system?