I have a strange fault that has started.

After about 5 mins of running on the road or standing, the throttle starts modulating.
If driving it gradually dies on the throttle, then starts modulating, if I floor the throttle it clears and takes off, if I turn off the ignition and restart, it goes away, its driving me bonkers.

O2 sensors changed, new Cat, new TPS, not a fuel supply problem because it will instantly kick down and rev.

No codes

All the vacuum pipes have been either changed or re-seated, no leaks.

I'm missing something somewhere.

 

Keen to see what happens here as my jeep has developed the same symptoms today.

I too have just changed O2 sensor.

 

I know this is a bit late, but it was the upstream O2 Sensor.

As mine runs on gas I can actually disconnect the sensor and it has little or no affect on running, if I reconnect it missed and played up like hell.

Got a geniune at £135.00 what a rip off, on gas there is not much if any difference between it connected or not.

 

At least it's sorted now. Although I replaced mine I still have a code 51 for running lean. I have replaced both my o2's and it still didnt fix that code. It seems to be running fine though. Or at least it was.

I'm now getting code 27 for something to do with the fuel injector circuit. As a result it's only running on 5 cylinders. My heater core also decided its had enough of holding coolant and now prefers to leak so I've bypassed it. I'm banging my head against the wall with this jeep.

Glad you got yours sorted anyway. Thanks for posting your fix!

 

Mine had a dead engine when I got it, so I had no experience of it running, for the first 6 months or so after the rebuild, when it started up I would get 3 long bleebs, always ran fine, and never showed any codes.
Then it started running rich, so I buoght a couple of after market O2 sensors, just cheap ones because I'm not convinced they contribute that much running on gas.
Once I had installed them the Bleeping stopped.
Engine ran spot on until this problem occured.