misfire 5.0

[cali-girl]

Help!!! Even the mechanics and GM can't figure this one out. I've replaced the EGR valve, thermostat, O2 senser, coil, distributor cap and wires, spark plugs, fuel filter, had all carbon blown out of the lines,replaced all the injectors and gaskets, had a code 43 (which now I'm not getting after replacing all this crap), and a pretty penny later, she still hiccups alittle but doesn't seem to stall at stop signs anymore, but the hiccup is still annoying. There is a hair line crack in the radiator which I'm replacing this weekend.(She sometimes starts to heat up at stop lights, hotter that the normal 215 - 220). I've been on numerous forums and so far I have no answer. This seems to be a common problem, but mine still isn't resolved. I have a 91 Z28 305, with 98,700 miles on her. This car is my baby and she's sick, Help!

[philly rs]

im not sure if 3rd gen's and 4th gens have the any of the same things in it, i would suggest a maf sensor, or throttle sensor. what was a code 43?

[wrightz28]

Code 43 is exactly what you stated in your thread name, misfire.

Mostly something is a rye in the EST circuit. When they did your tune up was the timing checked? Your loose plug could have caused it too. Covering the basics, check all the connections on the distributer that the are clean and tight, same for the sensor. And with the knock sensor, pay close attention to the wiring, it is subjected to alot of heat and may be cracked. If you do find it to be a bad knock sensor or other related issue, don't be alarmed ifit still does it for a bit (few miles) while the ECM is relearning the spark curve.

Your problem definatley sounds as if something in the ignition timing circuit is wrong.

[cali-girl]

Originally Posted by wrightz28

Code 43 is exactly what you stated in your thread name, misfire.

Mostly something is a rye in the EST circuit. When they did your tune up was the timing checked? Your loose plug could have caused it too. Covering the basics, check all the connections on the distributer that the are clean and tight, same for the sensor. And with the knock sensor, pay close attention to the wiring, it is subjected to alot of heat and may be cracked. If you do find it to be a bad knock sensor or other related issue, don't be alarmed ifit still does it for a bit (few miles) while the ECM is relearning the spark curve.

Your problem definatley sounds as if something in the ignition timing circuit is wrong.

Well I got the new radiator in her and now she doesn't over-heat anymore. Yeah!!! The hiccup seems to be alot less now so it might have been a pressure problem with the leak in the radiator. The distributor, wiring and timing was all checked ok and good. I believe the ignition was checked out but I will call the mechanic to double check, because we even put a brand new computer to see if there were any changes but it was no different which cancelled out the computor being a problem.But thanks for the info, please let me know if you have any other ideas.