Well my SES light came on right after i bought my 96 z28. I took it to the shop and they checked for codes it said that the 1 and 8 cylinders had a misfire. So i changed the plugs and wires. The code is still here. They scanned it again and now only cylinder 1 had a misfire. I took out the plug and wire to see if it was getting spark and it was. So i did a compression test on that cylinder and it read 165. I can't find out what it should be at but that seems to be okay. When i put the plug back in the light was gone but then after about 3 min. of driving it came back on. What else do you think could be causing this misfire. Do you think a dirty injector could be causing it? Would that put out a code? Also my car backfires sometimes. Do you think that is related or something totally different? I really need some help with this one. I can't seem to figure it out.

 

3 things cause backfiring, valve timing, spark timing or running lean. I'll go with lean. Time to check fuel pressure at key on, at idle and WOT.

clean the injectors. Replace the fuel filter.

check to see if pressure is bleeding down in the fuel system after the engine is shut off. Check the tank vent to be sure it is open.