1996 Jeep Cherokee 4.0 HO Auto trans, so I've been getting a sputter mostly on acceleration, it has backfired before and stalled, then I started it back up and it ran fine for a few weeks, now it's starting to sputter again. The check engine light is on for the downstream O2 sensor, but I don't have a cat(how the jeep came) and the sensor connector is just hanging out down there. New TPS new CPS new filter new pump good fuel pressure. I just think that it's interesting that it would run fine and then sputtering on and off? Could the downstream O2 sensor act up like that? I think I may have an exhaust leak too Thanks

 

Disconnect the front o2 sensor and see if it runs better.

It's probably bad also.

Replace your cat with a cheap one from performance-curve and get your exhaust and sensors set up correctly.

Not allowed to talk about running without a cat on this forum.

 

oh.. Wasn't aware of that, no emissions where I live, but anyways, I unplugged the TPS and it changes at idle so I'm assuming that is still working right.. I unplugged the upstream o2 sensor( I replaced this fairly recently, it was from Bosch I think) and it didn't change at all and the sputter is still there when I drive around. I thought the downstream o2 sensor controls the cat emissions and has nothing to do with fuel/air ratio?

 

When was the last time you did a tune up?
Downstream just detects if the cat is working or not.

 

havnt done a tune up on it, I just swapped an engine from another jeep into it

 

But what would you consider a tune up? I changed all the plugs and wires, most of the sensors are new, changed oil and filter..