Big dog1992

I have heard tht o2 sensors seldom cause plug misfires but I have changed all ignition and its still misfiring

otto457

Are you getting the same cylinders misfiring after replacing the ignition components or different ones?

Big dog1992

I have done the same thing to my 4.2 v6 replaced all ignition and still mis firing I have been told if u have a vacuum leak it will make it misfire id check for tht first bud

Big dog1992

Sorry though it was someone else havin same problem and yes I am it's the #6 cylinder I don't have vacuum leaks but it's still missin

otto457

Might want to check the compression on the cylinder and swap the injector from that one to another and see if it moves with it.

Big dog1992

How do I swap injectors

Def4life

What all have your replaced? The plug and coil?

Big dog1992

Plugs coil pack and wires
I had a vaccum leak an it cause 6 and 3 to mis fire I fixed tht but 6 is still misfiring

Def4life

Pull the wire and plug out of cylinder 6 but leave it plugged into the coil pack and run the truck just to make sure you are def getting spark to that cylinder. Just make sure when you do this you lay down a couple shop rags first and then set the plug with the wire attached on the rags. If you're getting spark then you either have a fuel problem or a lack of compression in that cylinder. If you want to check compression, your gona have to get a compression tester which screws into your spark plug whole. After you do that, get in the truck and hold the throttle to the floor boards and let the engine crank over a couple times and then check your compression after that. Holding it to the floor will cut off the fuel so it wont start, or you can also just unplug the coils, just be careful doin that cuz then fuel is still getting in the cylinders and if you keep doin that it will flood the cylinders.

Big dog1992

Thanks I'll see wat happens