XJNate97

Hey guys, I have been using this forum as my main source of XJ knowledge since I bought my rig 8 months ago. Thanks for all the info you guys share for the new guys!!


Anyways, I have a 1997 Cherokee 4x4, 4.0, Auto and I have been fighting issue after issue with it, I feel that Im getting close to the end of the problems though so I need your help in knocking it out and keeping my beast on and off the pavement


My XJ has a couple issues such as:


Air in fuel system. Was remedied by replacing slide on fuel pump assembly with rubber hose.
Hard Start(typically when cold, when at temp it starts right up)
Slight Misfire(causing backfiring through exhaust and intake)
Poor Fuel Economy(seems to be loading up pretty badly)
Stumble through acceleration(between 1/4 and 3/4 throttle, will respond correctly up to 1/4 throttle and slowly catch up if you hold throttle wide open)


I have done the cluster trick and got codes:


Code 51- O2 sensor detects lean mixture
Code 66- TCM to PCM Failure
Code 45- Which to the best of my knowledge is Overdrive Solenoid issue


In hopes of remedying these issues I have replaced the following parts:


CKP Sensor/ Duralast
Entire Distributor assembly including CPS, Cap and Rotor/ Duralast
Air Charge Sensor(Manifold Temp Sensor)/ BWD
Coolant Temp Sensor/ BWD
Also swapped MAP, TPS, IAC, Upstream O2 Sensors with junkyard parts, trying to narrow down issue. No avail.


I have come across some info naming a few culprits to the issues such as:


Poor Fuel Pressure
Clogged Injectors
Vacuum Leaks
Upstream O2 Sensor
MAP Sensor
and even CKP Sensor


I have not tested fuel pressure with gauge, but it appears to maintain good pressure. I have checked for vacuum leaks and everything seems solid, no leaks to be noticed. And as I stated CKP is new, but reading about some issues with Duralast Brand electronics I went back and replaced the CPS with original MOPAR sensor and noticed a slight improvement, and swapped CKP sensor with original MOPAR and saw no change so I reinstalled the new Duralast one. MAP sensor and Upstream O2 sensor were exchanged with junkyard sensors and no difference was noted so they are still currently installed.


Im not sure what else to check or where to start, ANY info or guidance would be greatly appreciated!!

CCKen

The '97 is an OBD II vehicle so you should be able to use the Data Link Connector to determine what "P" codes have been set. Also, if you can get a scanner that shows live data you should use it to find out what's happening with the various systems, especially Short Term Fuel Trim.


Check the O2S Heaters fuse in the PDC. Image says 98-99 XJ but the O2S heaters fuse is the same for the '97.





Inspect all wiring harness looms for chaffing through to the wiring within. Common issue with XJ's.

XJNate97

Awesome! Thanks for the info! I will check it asap and let you know what I come up with!

CCKen

Couldn't find the "P" codes for 66 and 45, but 51 is P0171. Here's the possible causes for P0171. It lists P0174 2/1 as well because this came from the 2001 XJ diagnostics manual.

XJNate97

Well, I checked the fuse for the O2S Heater and it was fine. As soon as I can get my XJ down here to the house I will be testing Fuel Pressure, MAP and O2 sensors and I will keep you updated as progress unfolds. Thanks for the tip on the O2 Heater fuse because I had found nothing online concerning checking for it. If anyone has any other advice as I look into this issue please let me know as I am new to Jeeps and am unfamiliar with their operating system. Appreciate the help guys and hope to have the issue resolved quickly!