Vehicle is a 96 stock Cherokee, has 159K mileage, and typically starts right up and runs fine.

Yesterday after driving 300 yds in the parking lot, the engine began to stumble at low RPM . I shifted to neutral, feathered the throttle,got it to rev up above 2K rpm, put it in drive, and it ran with cross tension between the throttle and brake. At the first light it repeated the same symptoms. It finally stalled, but restarted and with feathering and again revved up. Once up to speed ( 55 MPH), it ran fine. When I stopped in the driveway to let a passenger out, it repeated the same symptoms, but when I got in the garage, it idled fine.

The temp gauge showed + - 155 initially (with a 150 degree thermostat) elevated to 175-180, and stayed there. It was a warm day 80-90 degrees and the gauge increased to near 200 when I drove about the parking lot.

The AMP gauge shows 12plus amps.

I have already replaced the water pump and ALL the hoses, fan clutch, distributor, cap, coil, wires, plugs, fuel filter,. The vehicle has a K&N cold air filter.

Any revelations will be greatly appreciated.

goodyoleboy

 

Setting aside the use of an incorrect temperature thermostat, could it be as simple as a idle air control valve in need of cleaning?

 

Thermostat came with the vehicle. What is correct / better?

Is cleaning better than replacement? If cleaning is better, with what? Solvent, air, or ________??? Any adjustment to be made? I understand that some replacement parts are not as good as the original Mopar. Rockauto has replacements for $10-$35. Please elaborate good / bad / better brand(s). Any other related / suspect part(s) to replace at the same time / while I'm at it ? For maximum reliability, would I be better off to simply replace the entire throttle body or ???

goodyoleboy

 

I'd definitely try cleaning it before I replaced it. I use some throttle body cleaner and a rag. While you're in there, you may just want to pull the whole throttle body and clean that as well, particularly the area where the IAC lets air bypass the throttle plate. It wouldn't be a bad idea to have a new throttle body gasket on hand, since the old ones can fall apart when you pull the throttle body off.

The factory thermostat is 195F. 150 is way too cool and may not allow the ECU to go into closed loop, particularly in the winter.

 

Thank you for the insights.

Where can I find more background info on the fuel injection system? I barely understand the concept, a little bit of knowledge is a dangerous thing, and that's all I have.

What is an ECU and same question as above.

I chose the jeep because the mechanic who replaced the timing belt on the rice burner recommended it for its reliability because it only has one computer instead of three (or more!). Now I don't know that I can trust it as I once did not knowing what will be next and if / where / when it will leave me stranded on some mountaintop if I were to take it camping. I have no reservations about replacing whatever components may be necessary, but don't know which one(s). What am I missing? What is there that I can / should be doing differently? Just accept it as a given? Lower my expectations? I'm told the new ones are a nightmare of electronic computerized dodads just waiting to break.

goodyoleboy