Well guys it has been awhile, But there is always something coming up with the XJ......and this one has even the Jeep Tech stumped... anyway long story short, Took my Jeep to local dealer, thinking that they would have a better chance of fixing it...Nope. The Jeep is running like crap, It is fine went cold, sometimes a little hard to start, But went running is fine, till it heats up, then starts to miss at idle speed, and almost cuts off. The dealer replaced 1 injector saying it was bad, and the worked on the injector wiring hardness for 1 and 1/2 weeks to no end. They tryed to order a wiring harness , but couldn't find one. Then they said needed a new MAP sensor, well that was a waste of money, and still runs the same way. Ruff idle at low speeds, and misses, and can smell it running rich.

Soooo any help at this time would be Great......... Thanks ........Mouse

any way it is a 1997 Jeep Cherokee,,,,,Country model. with a Rebuilt engine, 3 years ago, automatic .

 

Any codes? Whats the fuel pressure? The dealer shouldve looked, but you never know with them these days.

 

I'd check for vacumn leaks.

I got a sweet almost free deal on mine because it literally wouldn't hardly run. All intake/exhaust manifold bolts were loose causing a huge leak.

 

nope no codes showing now. Haven't checked fuel pressure, don't have a gauge for that one ? I do have a CHECK GAUGES LIGHT ON, and have found the alt is bad. a have a new one on order now. Only charging 13 volts to battery.

Thanks for any help........ Mouse

 

Did they replace the O2 sensor? That's often a culprit of it running poorly once it warms up and tried to go closed loop. Crank sensor too, but that wouldn't explain the rich smell. If you thought you had a bad injector, I would have replaced them all with a set of refurbished Bosch. I imagine they charged a pretty penny for a single oem though.

 

I had that issue on my sonoma a long time ago, ran fine when cold and when it was warmed up it ran like garbage, it was the coolant temp sensor. It wasn't telling the computer to lean it out after it warmed up and was still dumping cold temp fuel amount when warmed up. Swapped the sensor out and it ran great.

 

Easy enough to check with a meter. I'd hope the dealer would have noticed it reading wrong when troubleshooting though.

COOLANT TEMP SENSOR & MANIFOLD AIR TEMP SENSOR RESISTANCE TABLE
Temperature *F(*C) Minimum Ohms Maximum Ohms
-40 (-40) .............. 291,490 .......... 381,710
-4 (-20) ............... 85,850 ........... 108,390
14 (-10) ............... 49,250 ............ 61,430
32 (0) ................. 29,330 ............ 35,990
50 (10) ................ 17,990 ............ 21,810
68 (20) ................ 11,370 ............ 13,610
77 (25) ................. 9120 ............. 10,880
86 (30) ................. 7370 ............... 8750
104 (40) ................ 4900 ............... 5750
122 (50) ................ 3330 ............... 3880
140 (60) ................ 2310 ............... 2670
158 (70) ................ 1630 ............... 1870
176 (80) ................ 1170 ............... 1340
194 (90) ................. 860 ................ 970
212 (100) ................ 640 ................ 720
230 (110) ................ 480 ................ 540
248 (120) ................ 370 ................ 410


Info for the older Renix Jeeps, in case someone stumbles across this and doesn't realize the non-HO engines are different.
1988 FSM CTS & MAT SENSOR TEMPERATURE-TO-RESISTANCE VALUE
*F (*C) Ohms
212 (100) .................................. 185
160 (71) ................................... 450
100 (38) .................................. 1600
70 (21) ................................... 3400
40 (4) .................................... 7500
20 (-7) ................................. 13,500
0 (-18) ................................. 25,000
-40 (-40) .............................. 100,700

 

As Lawson mentioned; I hope they did some thorough diagnostics, but wouldnt hold my breath there.
Only one faulty injector wouldnt make it run so bad it would stall imho.

Mine gave same symptoms as yours , when my CAM sensor went bad. Same symptoms as CPS going bad, but the fuel smell from the exhaust was the only difference, pointing to the CAM.

 

Yes, most people don't know the cam sensor is for injector timing and has nothing to do with the ignition. I'm thinking it has more to do with closed loop mode involving engine temp and 02 signals. Unless you find a good one, most dealerships don't like to work on anything more than 5 years old because they take a long time to diagnose and they usually have to order parts. The dealership near me charges a $100 electrical diagnostic fee on every car that comes in, for whatever reason other than an oil change. I needed a serp belt idler pulley that day because I was going out of town and needed it fixed in a hurry. They charged me that diagnostic fee and when I asked the service manager why, he said every car gets charged that! WTF?

Some dealerships actually put older cars lower on the priority list than cars they have sold. It has to do with the bottom line...profit! This one will not touch lifted vehicles supposedly because of liability issues. There is one dealership about 50 miles away that will, with the caveat that they won't be responsible for safety issues.

 

They didn't change any 02 sensors, Will look into that one, Thanks. The crank sensor has been changed, and that is also a good though about the water temp sensor. also will check it out, Thanks.
They only changed 1 fuel injector that was bad, so they said. Well they did have the XJ for over 2 weeks, and guess they worked on it some times. They told me that to go deeper into the engine, would cost a good deal more... all ready spend over $1,000 this time ? I love this XJ, and want it to run good again, just hate to keep throwing more money at it. ...............Mouse

 

You say there aren't any codes coming up now (also no CEL?). How are you/they checking for codes? Certain criteria need to be met before the PCM will show a code/codes. Sometimes no CEL will come on. In these instances the hand held scanners may not show codes. If it hasn't already been done it should be scanned using a scanner such as the ones used by the parts stores who will do it for free and give you a print out.

 

Man I feel your pain.... I love my XJ too... it's my DD... and now living in a very large city puts an extra toll on it that it hadn't had before. To me my XJ is part of the family... but my wife is kind of pushing for me to sell it and get a truck.
On one hand I hate the idea... on the other... I wonder how long can I keep a 22 year old jeep rolling for DD consistently.....
hope your issue is resolved in short order now

 

Thanks Rocket, Nice to hear someone else feels the same way..I know it is getting old and so am I ! But now it is a classic piece of crap, with some parts being hard to find, or can't. Just trying to keep it rolling a few more years, and trying to get this running issue worked out. With the weather getting better now, I get more time to play with it, and see if I can get it to run right.

Thanks for any help and some insights.............Mouse

 

car-parts.com greatest web site ever if your still looking for the harness.

 

Tell me that ain't the truth...... they don't like anything that they can't just plug in and run through their fancy equipment that tells them what's wrong or what to do 1st, 2nd, 3rd... etc. it makes them actually have to work to diagnosis a problem and let's face it, a lot of them don't have the old school knowledge of wrenching.

and what you mentioned about the diag fee... seriously... just extra dealer profit... kinda like buying a car and saying oh please, can I pay the "dealer prep" fee? lol...