Alright I have a 96 Z28 and it misfires. At startup it will idle fine and during the engine being cold, but once it gets to operating temperature it will begin to misfire throughout acceleration. If I throw it down say in 3rd gear and punch it, it runs fine and no misfire and seems to have alot of power. But also when I launch through first it seems fine but when I hit second and get to a high rpm it's like its reving high but the wheels arent turning while it's in gear. I think alot of people call this cam surge, like if I stop and it still idles at 2K then drops slowly. I don't know what the prob is. I replaced the Opti, Coil, Wires, Plugs, and it still does it. Even tuned the valves. I dont know if the cam is worn out or the lobes got flat but I need some help. This could be anything, maybe even a bad harness or PCM or vac leak. Well if anyone can help or has any suggestions let me know. Also it had a code P100 not too long ago that I deleted and it never came back but I tested the MAF and it wasn't bad. 972-679-5322

 

Anyone?

 

It sputters, misfires, and then cutsout. Any way to check for fuel related problem.

 

Since you already had 1 MAF failure, it's best to eliminate it PROPERLY. You need a multi meter that reads frequency (Hz). From the yellow wire to ground, there should be OVER 7KHz when the throttle is snapped with engine running. If less than 7KHz, clean first and try again. If still low, replace.

Then move onto fuel by checking pressure at the schrader. I suspect you have a restriction however and pressure will probably read fine. You could check to see what the O2s are reading but that probably won't help you either. If your running lean on any cylinder, you could have an exhaust gas done.

Best to see which cylinder is missing (check the misfire counters) and then independently shut down that injector to the cylinder in question with the scanner to see if the running condition stays the same. Without the scanner, you could do the same thing by removing the injector connector. If the running condition stays the same, there is a chance the injector is not flowing. At that point you want to check it with a noid light and also confirm spark to that cylinder. If both of those are ok, try swapping with a good injector to see if the problem follows the suspected bad injector.

 

if it runs fine while its cold, then runs like puke when its warm.

oxygen sensor(s); unplug them after the car has warmed up and see how that works. If this works, that means your o2's are fawked.... it COULD also mean that you have burned wiring along the way to the o2 sensor (what a treat to diagnose and fix!)

but its probably just screwed o2 sensors

edit: oh also, if you have headers - get rid of them and get something that doesn't destroy wiring (longtubes tend not to do this so badly i think)