P0300 Misfire Code Help
 

New member, looking for some insight here.

I have a 1998 Chevrolet Camaro, 3800 V6, five-speed manual transmission, 123,000 miles and bone stock. This makes my second 3800-powered F-Body after my 1998 Firebird which was totaled by an idiot driver. I haven't had the car a month yet and it's giving me the dreaded P0300 Random Misfire code.

So, I replaced the obvious, simple culprits: the plugs, plug wires, and one coil pack that had corrosion on the number one cylinder contact point.

That didn't fix it.

I had a compression test run. Every piston checked out.

So, after driving the car a bit and looking for clues during and after the drive, I notice my catalytic converter was getting red hot. I thought, Ah-ha! So the either the catalytic converter is going bad or it's burning raw gasoline somehow.

So I replaced the cat itself because I sort of figured it would be a least likely culprit sort of thing.

Nope, still nothing.

Then I tried to see if it could be a fuel delivery problem and bought the best synthetic fuel injector cleaner I could buy.

Nope, still runs like s-h-i ... you know the word.

And it's strange because the car did it in the middle of a trip going to town. No warning, no provocation. The car was running excellent, basically like new; plenty of horsepower, no hesitation, never skipping a beat. Then -BAM. It's running worse than some of the other F-Bodies I had test driven before it.

So I am reaching wit's end with this car. And with money running very low, I'm honestly getting close to finding a way to get rid of it.

If anyone can lend any insight as to what might be causing it, I'd appreciate it. I know the only parts left to check are the 02 sensor, which I'm about 90 percent sure isn't bad, the fuel injection system which I also doubt is going bad, and the EGR, which again I don't think is bad.

I don't know if this will help you but my son-in-law has an 03 Tahuo and had the same problem and it ended up being one of the 4 O2 censers. The thing ran like S@#T, missing and running black soot out the rear exhaust. I really thought it was something worse then that! 3 days in the shop and $300 later, she runs like a dream. As I said, not sure if this will help but if you have not checked the O2's out, it may be worth doing. Good luck.

whats your fuel pressure? have you changed the fuel filter? did you check or replace your o2's

Ran a fuel injector psi test and it's returning 43 - 48 psi. Factory specs are 48 - 55 psi. It's on the low end of the spectrum but nothing that would really suggest a dead injector to me.

I solved the problem a few days ago and replaced the ICM. No more P0300 code, but now the muffler is rattling like a tin can ... no big deal. It's looking like I'll replace the whole exhaust system from the cat back with a Flowmaster or Borla system.