98 3.8L @ 65k

Ok I have done a lot of searching both here and another forum. I have noticed a lot of v6 camaros with misfiring problems. So I will contribute mine as well...

Monday morning I went to leave for work and my SES light was on at the turn of the key. Sunday night the car was fine. Go down the long driveway and nothing seemed to be wrong except the SES was on. Go get on the highway and get the car up to speed, set the cruise and still nothing. Start getting to the hill and the cruise starts to apply the accelerator and the car starts missing, backfiring and rattling violently and the SES starts blinking. So i back it off and baby it, the blinking stops but SES remains on. As I get closer to work the situation gets worse. Leave work, the problem seems intermittent when the car is cold and constant when the car is hot. Go to Autozone by work and they tell me its a p0304 - #4 cylinder misfire and it is showing up twice on their scanner.

No big deal. I go inside and buy plugs and wires. Go home and diagnose a few other things before I change plugs and wires to see if I am able to return them. I am cheap what can I say.

The #4 injector passes the ohm test at about 12.4 ohms. #4 wire passes the ohm test at about 28,000 ohms. I also took an old plug off the bench and through it into the #4 wire and there was spark. The spark did not seem as strong as it was through #6 wire but that could have just been my thinking. Not sure. Have to limp it back and forth to work Tuesday.

Change the plugs and wires eventhough the resistance test passed. All the plugs look normally used except #4. It had noticeably been arcing on the ceramic but it wasnt wet like i thought it would be from the misfire?
Under closer examination I notice a slight crack in #4 plug. I gently pick at it and the plug breaks in half. Must have been the problem right?

Well get everything together, disconnect the battery to clear the codes and then take it for a road test. Seems to drive just fine for the first leg of the trip. One little sputter leaving the driveway. Let it warm up and then jump on it a few times and everything still seems fine. Except when the car is under high load in high gear. Then it has the missing feeling but it is far more intermitant and stretched out than it was before. It is also not throwing any codes now. The SES light has not been on since I changed the plugs and wires.

So where do I go from here? Is there a way to test the coil packs other than switching them? I am not getting a code now so if I switch packs, i will have no way of narrowing the misfire down. How likely is it that the injector passed the resistence test but is still the problem? I am also not getting an 02 code. I can check and see if the cat got junked up from running with a miss for two days by seeing if its "red hot" right? Will the cat clear out any possible unburned fuel that made its way in or does the cat just junk itself?

Other than that I am at a loss of ideas. Any suggestions would be helpfull. Thanks.[/align]

 

Personally, I would first change all the plugs and wires. Then get the coils and ignition module under the coils tested (many parts stores do the testing free). If you can get a scanner check for lean running condition. Of course, as you mentioned, a lot of raw fuel in the exhaust will overheat the cat and melt the stuff inside and cause it to clog, but your description does not indicate that is the problem. As for the injectors, just because the coil looks good does not mean the mechanical pats of the injector are working, or that the injector is being fired. The injectorcoil check is only one part of the testing.

 

OK well after a weekend of working on the car, the situation did not get any better.

Changed plugs and wires.

Changed injectors.

Changed coils.

Tested ICM. Tested strong.

Cleaned EGR and PCV.

Fuel pressure is good.

Tested injector connection with a test light. Injector is firing.

Sprayed carb cleaner and propane around intake manifold to check for leaks. No change in idle.




Anybody else have any other suggestions??? I am about out of ideas.[/align]