I have a 2000 dodge ram 2500 with the 5.9l gas engine. I just bought the truck and it's backfiring when in higher rpms and when trying to accelerate. The person I had bought it from put a cold air intake on it but it don't look right like it shouldn't be on that engine. Also the o2 sensor isn't plugged in due to the previous owner decided to cut the wires from it. It did sit without being drove for a little while ( maybe a year ) anyone have any advice as to what could possibly cause it backfiring?

 

Welcome to DF.

Which O2 sensor is cut? If its the one in front of the converter, the engine needs that to run correctly. The back one just decides whether the catalytic converter is working or not.

Will move you to the correct section for better help.

For future reference:
https://dodgeforum.com/forum/dodge-r...ead-first.html

 

the engine should run ok even without either O2, although it should set a code and turn on the yellow CEL light.

have you done a basic tune up yet? plugs, wires, cap, rotor. while at the cap and rotor, take a close look at the cam position sensor (aka secondary pickup coil, secondary ignition coil) which is under the cap and rotor and has a critical wire behind the engine block.

 

still the old gas in the tank?

 

It doesn't have a converter on it. The previous owner had put a different exshaust on it. So there is only on sensor on the pipe that I recall and that one isn't hooked up

 

Still have not yet done a tune up on it that is next on the list of things to do to it. I'm sure it's needing it do to it sat for a while. So with hope with a tune up it might clear it up and run correctly.

 

It hardly had fuel in it when I bought it. And I've ran it out of gas then I put a couple gallons in it and drive it around a few times with fresh fuel. So maybe all the old gas hasn't worked out yet.

 

Need to hook up your O2 sensors. At the very least, the pre-cat (when you had a cat... sensor. Leaving either/both unhooked will compromise performance, and fuel economy, and give you a perpetual check engine lite.

Do the tune up. Plugs, wires, cap, rotor, air filter. Reset PCM. (just disconnect the battery for ten minutes or so.) See how it runs.