Hey everyone, im fixing up a camaro that i bought 5 months ago. It was having misfiring issues when i bought it and everything i could remember looking up on the issue with this car said that intake manifold gaskets were a likely suspect. So i replaced the upper and lower manifold gaskets, throttle body gasket, spark plugs and wires, and even installed a CAI. The car runs great in park and neutral. put it in drive and it begins to misfire again. I was told to check the ground wire for the coil packs and maybe check for a vacuum leak. From my own research i have eliminated a clogged catalytic converter due to the fact that there is no rpm change when changing it from park or neutral to drive so there isn't anymore exhaust being pushed through the cat. Anyone else's advice would be greatly appreciated. Also has anyone else had something like this happen to the before? thanks guys

 

did you test the fuel pressure yet

 

Are you getting a random miss fire code in the PCM? It is very common for misses to not show up on a no load idle. This could easily be a failing coil or a bad sensor messing with the fuel mixture. It really could be a lot of different things even a failing ICM could cause this.

I had one on my 3800 a couple of years ago that ended up being the connector to the MAF sensor. I would get a miss and a random miss code everyday and twice in 3 weeks I got a low voltage at MAF sensor code. I replaced the MAF sensor and the issue went away for a week but then came back but no MAF code just the missfire code and the miss. Then while moving around I bumped the harness the the idle when real ruff, replaced the connector miss gone.
I am not saying its you MAF sensor connector I am just saying it could be a lot of things.

I did also replaced all the coils they are really only dependable for about 15 years.

 

thanks for the quick responses! and to answer the questions no i havent checked the fuel pressure or even ran a scanner on the car yet, but my buddy has one and we are gunna run it this weekend and see what comes up. i will check the fuel pressure and see what shows up there. thanks again!

 

sorry for the long wait i have been working a lot and going to school full time i havent had a lot of time to spend on the car. i ran the fuel pressure and it came up good. i scanned the car and only got a engine coolant temp sensor code and no code for a misfire. i replaced the coolant temp sensor and the ses light went away for about a day. the car is now misfiring worse than it was before so i believe it is either a coil pack or the icm. i am going to replace both of them and see what happens. i also replaced the iac valve and the throttle position sensor.

 

check all your wiring to coils, look for damage. also make sure plug wires go to the right plugs.