coreyscx

Vehicle - 96 Jeep Cherokee Straight 6 4L (classic)

So first of all im new to the forum so im sorry if this is the wrong sub forum, but as the title states my cherokee humps down the road, if you pulled it out of the driveway and floored it, it would go then die down then go and die down all while not moving your foot. also the throttle body's choke is sucking in way to much air, probably about x5 the amount it needs. It does backfire if you give it more gas, hesitation is apart of it too. If you watch the rpm's at idle the needle will jump down then the engine runs itself to try and bring them back up.

Parts we changed

1. Fuel Filter
2. Throttle Position Sensor
3. Idle Air Control Valve
4. 1 Spark Plug that was misfiring and the wire with it
5. Distributor Cap
6. Rotor
7. Crankshaft Position Sensor
8. Top Radiator Hose

I previously replaces the air filter and we did check all the wires and plugs, the rotor in the cap and the cap itself were put on correctly, and i checked the engine codes the fuses are all good too

Engine Fault Codes
12 21 21 35 56 or if you consider this model an obd2 then 122 121 355 6

Maybe the timing or transmission i mean we tryed mostly everything else ive been browsing this forum for days doing everything it said so now i figured id post my problem myself. I need this vehicle up and running as its my only vehicle to work so any help is really appreciated. Thank You.

VTJeep

sounds like fuel delivery. its odd that it does it when WOT. how about o2 sensor? these will wreak havoc on fuel delivery. or the pump and/or filter itself.

coreyscx

i changed the filter i havent changed the o2 but i dont have a cad convertor so the back o2 wont do it, havent managed to get the front one off its torqued in pretty good. but is there anything else it could be besides an o2 sensor?

coreyscx

also it does it when idling too, it sounds like the engine is chocking itself with all that air its sucking in and the hesitation and humping on the road is hugely noticeable

VTJeep

if its not the upstream o2 ill be amazed! get that sucker out if ya can, heat and lots of PB!

how did filter look when replaced? i had a bunch of debris in bottom of tank, dunno how- leaves, sand, etc, and that had a big impact on delivery especially on down hills..

coreyscx

ill try it thanks man. if anyone else has any suggestions please mention em.

coreyscx

the filter was the one from 96 lol so the new one looks alot better