Hello e everyone any help would be great I have had this truck for about a week! When I got this truck the passenger side exhaust manifold was broke in to. So I replaced it but the truck is backfiring a lot and is missing . this motor sounds like it has a great motor until acceleration then it starts the mix. I have changed the plug and wires and no change. When I changed the plugs the ones on the passenger side were covered with sutty carbon and the drivers side was clean and look great. I don't know how much the truck was drove with the manifold in to. It Strick's me odd for this to be on the passenger side only . I tried to find a intake manifold leak and no luck!! PLEASE HELP!!!!!

 

Any OBD2 fault codes?

 

Check Or Recheck the Wires, to make sure they have been installed correctly. Also test the coil pack as it may be bad?

To assess if the truck had been driven for a long tyme with the broken manifold, You can do a Compression test to see if the valves are damaged.

 

No codes

 

I have check and rechecked wires look good and how can I test the coil ? I have check to see if it is firing it appears to be good! (Not) that I know anything but in the past I have never had a coil to have 3 outputs go down. Could you give me some info on how to see if it is firing correctly? It seams to smooth out a little after the trucks worms up. I don't have a compression tester. Is it possible for all 3 cylinders to have burnt valves. Thanks fellas for the help! ! ! ! !

 

Most parts stores loan or rent compression testers.

 

Here is a Picture of the proper firing order for the 4.2L V-6
https://www.f150online.com/forums/me...42-157048.html

I had the same problem you are discribing (SP?) & I ended up having 2 wires crossed on the drivers side.

All it takes is One Burnt Valve.

Good Luck!

 

Did you ever figure it out?