99 dodge ram 5.9 4x4
Alright well heres my problems whenever i start the truck it runs and idles great but after warming up it runs rough and stalls when looking at my scan gauge it only starts to run rough when the oxygen sensor go into closed loop the oxygen sensors have been replaced before and it still does the same thing. I unplugged the sensor and ow the truck drives fine. Could this be a plenum gasket problem?

 

Yup, and the cat is probably clogged.

 

Well i didnt take the sensor out of the cat i just unplugged it and the truck doesnt smoke but it loses about a quart every oil change.

 

Unplugging the connector does nothing, you have to unscrew it from the bung. Either way, sounds to me like you have a blown plenum gasket.

 

Alright well whenever you unglug the oxygen sensor the truck no longer uses the oxygen sensors for tuning it runs on a preset mixture.

Soo if the plenum is leaking does that mean raw air will get into my exhaust and cause the oxygen sensor to detect more oxygen and increase the fuel mixture causing it to die?

 

yes, but that doesn't help with diagnosing whether or not the cat is clogged.

 

well i guess ill try that later. Im guessing the symptoms are there. I cleaned the throttle body not to long ago and i saw a small pool of oil laying in the intake. And when i replaced spark plugs i also noticed that there were two plugs that were oily. Does this indicate i have a blown plenum like in the plenum thread.

 

Yea.......