My cherokee is running too rich. It'll run fine for a minute or two then starts to loose power and rev up without moving the peddle and continues in idle. The smell of it running rich is thick.

I'm running a 98' cherokee sport with a straight pipe and no other engine or fuel system mods.

Anyone have any ideas? Please help

 

First, you need a cat in the system for proper back pressure. Your ECM is calibrated for that. Second, when was the last time you changed your O2 sensor?

 

i thought i should put one in, but when i posed the question my mechanic didn't think the cat was that necessary.

the o2 sensor that would be behind the cat if i had one was replaced about a yr ago. the other far as i know is the original.

 

If you don't have that cat, I imagine your ECM doesn't know what it is supposed to do. I would recommend you put one in and freshen up that sensor that would be in front of the cat.

 

i have a 95 xj that did something similar to that.. i changed the tps sensor just to checklist it.. and it came back that was the problem.. runs great now.. who knew..

 

replaced the tps with no change. i'll be checking into getting a cat. what are your thoughts on it being the fuel pump?

thanks all

 

That wouldn't be it. If it was, it would be running lean.