Lowrange2

My wife's XJ did something similar. In our case, a new upstream O2 sensor solved the problem.

Bogged, stumbled and backfired for the first 2 minutes it was running. After that it ran smooth as butter all day.

rm2406

i did replace my o2 about a month ago with a denso brand. do you recall what brand you used in your cherokee? i accidently dropped it but it seems to be working fine, but im unsure if the heater element inside might of got messed up. i need to find out how to test o2 heater only... i understand this is used during warm up period. after warm up my jeep is great!

Lowrange2

Right, that was the problem.

Check continuity to the wires on both sides of the heater.

rm2406

do i check the heater in ohms? or do you mean test the sensor itself??

cruiser54

YOu could test your IAT sensor. Worst case, remove and clean it.

rm2406

how do i test the IAT sensor?

cruiser54

There's a chart in the FSM will what ohms values equal what temps.

Just clean it first.

Roler

OP,

It would be handy for us to known if you mention all the things you already did, BEFORE asking and getting advice. Just reading through this, with all the suggestions given, almost all your replies state that you already did them.

It brings things up to speed, if you state the problem, then what you already did in diagnostics or what you already replaced, as in tune-up, cleaned injectors, replaced O2 sensor etc etc.

So, maybe anything else you've already done, but forgot to mention?

rm2406

Apologies...
Whats been done was due to passing a smog test recently but this is what was replaced new no more than about 3 weeks ago. plugs-wires-cap&rotor-ect sensor-map sensor-o2 sensor-fuel pressure regulator-oil change-air filter-2 treatments of berryman b12 chemtool fuel treatment-fuel injection service through rail-cleaned iac valve-vacuum hoses-battery.. all new.