I have a 2001 Jeep cherokee sport 4.0

My CEL came on and threw P0171. I tested the fuel pressure and it was consistent 45 PSI when I tested it. The engine does idle a little rough sometimes.

Next, the engine started randomly dying. No bucking, just instant death. The lights and radio stay on, the engine just stops running and leaves me coasting. Typically it would start right back up. At first it was intermittent, about once a week, typically in colder weather with light rain. I took it to a shop and they found nothing so I drove it home and it died eight times on the way home, go figure!

I took it for one more test drive and the gauges all died, leaving a NO BUS.

After some searching I determined the CPS might be to blame so I swapped that out. It was immediately better.... for one day. I drove it again and the gas pedal was not very responsive, it threw P1494. The gauges died again and threw NO BUS, but came right back on before I could scan for a code. Yesterday after work it died in the same spot it has done a few times, taking a turn and hitting a metal grate in front of my house. I coasted it in and it wouldn't start. I came back later and wiggled some stuff around looking for electrical problems and it started right back up. As of now, it cleared itself of the P1494 but threw P0171 again. It currently starts right up but idle will fluctuate from 750rpm down to about 500 intermittently, engine shakes more than usual and retains the risk of randomly dying.

Summary:
P0171
P1494 - cleared itself
Roughish idle
Randomly dies
Poor throttle response

Spark plugs six months old
Cleaned IAC
Replaced CPS
Battery has good voltage
Fuel pressure 45 psi when tested


No idea what to look for next. Sounds like I have multiple issues.

 

I would definitely be looking for breakage or shorts in the CPS circuit wiring.

I would agree with multiple issues. I can't think of anything causing NO BUS that would kill the engine.

 

You may want to examine the wiring at ground G101, then remove the wires from G101, scrub the ring terminals using a Scotch-Brite pad, then reassemble securely.


Note that the PCM and TCM are grounded here.


Corroded connections here have caused No Bus issues. If the CCD Bus goes down completely it will shut the engine off.



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P0171-1/1 FUEL SYSTEM LEAN


WhenMonitored: With the engine running in closed loop mode, the ambient/batter temperatureabove 20 deg. F and altitude below 8000 ft.


SetCondition: If the PCM multiplies short term compensation by long term adaptiveand a certain percentage is exceeded for two trips, a freeze frame is stored,the MIL illuminates and a trouble code is stored.


PossibleCauses


INTERMITTENTCONDITION


RESTRICTEDFUEL SUPPLY LINE


FUELPUMP INLET STRAINER PLUGGED


FUELPUMP MODULE


O2SENSOR


O2SENSOR SIGNAL CIRCUIT SHORTED TO GROUND


O2SENSOR HEATER OPERATION


TPSVOLTAGE GREATER THAN 0.92 VOLTS WITH THROTTLE CLOSED


TPSENSOR SWEEP


MAPSENSOR OPERATION


ECTSENSOR OPERATION


ENGINEMECHANICAL PROBLEM


FUELFILTER/PRESSURE REGULATOR (HIGH)


PCM

 

Thank you for the replies. I looked into the grounds, none looked too crazy but I cleaned them and will see if that fixes the randomly dying issue. One thing interesting happened as well. I picked up some Seafoam and went to my brothers house to have him help me add it to the intake. We noticed when he squeezed on the main intake hose from the aftermarket air filter, the engine would immediately die! Are there any sensors in the throttle body that would kill the engine if they sensed a restriction in airflow, or could possibly just be dying themselves with a light wiggle, and their absence causing the engine to die?

BTW, the engine idles much better after the seafoam treatment, but I am sure it is a bandaid.

 

The Crank Case Ventilation system on your 4.0 has a fixed orifice fitting on the rear of the valve cover- a calibrated intake leak. If the orifice gets plugged or if you pinch off the hose(s) the engine will die. If you remove the rear hose from the intake the engine will race.



.

 

I replaced the PCV valves and grommets and cleaned the throttle body. The jeep is idling well and the codes have disappeared for now. I also noticed that the air filter had rubbed into some of the wires from the computer. I am not sure how I missed it, but hopefully that solves the randomly dying issue. Thanks for all the replies and I will come back if the dying continues!