The truck was running fine before all work was done. I pulled the intake and installed a new plenum plate and gasket. I replaced the timing chain and water pump and bypass hose at the same time. I also installed a set of long tube headers. All this was about two years ago. Ever since the install the truck will back fire and shoot a flame out the passenger side header. I thought it was just because the exhaust had no back pressure and the o2 sensor was at the very end of the header and not reading correct. After the install the truck was parked for 2 years. I just got a full exhaust from the headers back with duals an h pipe and 2 cats and 2 mufflers. It is still popping. My first thought was it could be out of time. But it’s easy to start and only popping out one header. I’m thinking maybe check all the plug wires to make sure they are all seated good. Any other ideas? I will go pick the truck up Friday from the shop just don’t know if I should drive it home with it back firing or not.

 

Is it a consistent backfire? Time to one cylinder?? Might try a compression test. Might have an exhaust valve stuck open, or burnt valve seat.

 

no it’s not really consistent. Sometimes you fire it up and it doesn’t do it and other times it will

 

Might be as easy as a leaking injector.

 

idk just seems weird that the truck ran fine when I drove it into the shop to swap the intake. Then it’s backfiring after the install. I’m hoping it’s a plug wire or something easy. The only other thing I can think that changed is I put a different o2 sensor in when I installed the headers because I couldn’t get the good one out of the exhaust pipe. I have it out now. Maybe I should swap that first. But again seems weird it only happening out of one bank.

 

What brand 02's? Stay away from Bosch! I would check the wires one may not be seated all the way on the plug or cap. I assume you deleted the EGR.

 

I’m not sure what brand the one that’s in there is. I think it’s the factory one. It was in the exhaust when I bought the truck back in 08. Yea I pulled the egr tube off and plugged the hole in the intake. Left the valve plugged in.

 

I'm guessin' you had single exhaust before "the conversion"? If so, with the headers n custom exhaust, is the O2 sensor now only single siding (1 bank of cylinders) on the engine or still on both exhausts as they come out from the headers? This could absolutely mess with your computer trying to compensate for the loss of 1 bank of cylinders.

 

well before I put on the headers it was running stock manifolds into a y pipe where the cat was then into a glaspack then to another y that split to the tail pipes. The o2 sensor was in the y reading off both banks. Now it’s in the pass side header until I extend the wire and it’s goin into the H pipe. .

 

That could be your entire problem. Unplug the O2 sensor n see if the problem goes away, or is greatly reduced.