I installed my headers a while back and since then I've had an intermittent missfire. When it occurs the service engine light flashes and the miss is so bad it barely runs or moves. I had a similar problem a while back and I replaced my intake gasket and it went away. The coils apear to be fireing well (jumped the gap from coil to wire when I pulled the wire off coil) fuel pressure is good. Any help would be great!

 

Did you remove the plugs when you changed them?

 

I would make sure that the fuel pressure is good when the issue occurs, also I would do plugs and wires while you are there. Give the truck some new plugs and wires when it's got header install. Also make sure you get heat wrap for the wires aswell as the wires could get to hot to handle the flow of the spark, and with age it could just be an issue when hot. Any other mods?

 

I had my buddy read the codes today and it said random misfires and lean codes on both banks. I also checked the fuel pressure and it has right at 50lbs at the fuel rail and has plenty of volume. I also sprayed some break clean around the intake trting to find a vaccum leak and didnt find anything but that doesnt mean there isnt one. Could this be a PCM issue?

I also have a basic performance tune if that helps any

 

Make sure you don't have any exhaust leaks. Such as manifold leaks because as exhaust is pushed out of the head, it creates and vacuum,so it may not necessarily leak out but sucks air in and the o2 sensors see that the car is "lean" but it's not and adds more fuel and creates a misfiring issue. Also make sure you are using the correct o2 sensors is the right spots.

 

Ok I will investigate that. It is a possibility Bc it has has just started since I put the headers on and has progressively gotten worse. But I had terrible exhaust leaks at the stock manifolds before I put the headers on and it wasn't causing any issue

 

More than likely it was just pushing the exhaust out, not sucking air in. Watch the o2 sensors when you spray the exhaust and see if the switch faster