Hey guys, tried posting on camarov6.com, but no luck. Maybe someone here can help me out. Here's what I posted:

96 firebird 3.8:

So I got the p0441 code along with a p0304 code and checked the evap purge solenoid and switch and noticed I had a bunch of charcoal all in them, so I must have a bad canister. Could the charcoal, or bad solenoid or vacuum switch cause the p0304 misfire?

I know the misfire isn't from a bad wire, coil, or plug. What should I check next? Icm, fpr, injectors, iac? Some of these are pretty expensive to replace, so I don't want to replace something just to find it wasn't the problem. May be a clogged or dead injector, but not quite sure exactly how to check it, or where I can go to get a write up. I just seafoamed not even a month ago, and I use 91+ gas, so i dont see how the injector is clogged. I don't think its the egr, cause I'm not getting a code. Getting good sparks out of the coils, so I'm thinking the icm is fine. If it was a bad fpr, wouldn't more than just the 4th cylinder be affected? don't think its the maf, cause I'm not getting a code.

I have a small exhaust leak about half way through the catback, took it to the shop to get welded, but can still hear it poppin. Can't take it back to the shop to weld it again cuz the shop burnt down the day after I had it welded lol. This leak shouldn't be causing a specific p0304 code should it? I'm gonna clamp it shut this weekend.

The misfire is pretty rough at idle and at lower speeds, but when I get on it or while going at highway speeds I don't feel the misfire hardly. I'm also hearing a constant pinging noise, even at idle, which I think is coming from the misfire in cylinder 4. Spark knock? Something worse?

Could it be the iac? But if it were why would it only affect the 4th cylinder?


Thanks for any and all help.

 

P0304 pins the misfire down specifically to cylinder #4. I'd swap a couple injectors (#4 with another cylinder) and see if the misfire follows the injector.

An exhaust leak on the catback (well after the O2 sensors) will not cause a misfire.

The "ping" would represent a problem. The knock sensors should be preventing it. You should never hear spark knock if the system is working correctly. A cross-fire between cylinders might cause audible knock, if the spark is so far off it exceeds the PCM's limit on how much timing it can pull. Are you sure its not an exhaust leak at the manifold?