02 jeep grand cherokee cuts off after reaching running temp. 4.0L no check engine

Hi, check your pulley bearings, but if you have had the belts checked the mechanic should have picked up on that.

ever do a real tuneup this decade
spark parts, and filters. that be first
and make sure the hot engine (sized not stated) is really hot.
180F or more, and holds, it must reach normal spec, temp.
or the ECU brain will not do its job right.
the only clue I have here is skips
skips must mean misfire.
there are over 50 causes of misfire.
bad spark plugs tops the list.
and all spark parts there, cap/rotor,wires set this OLD.
car is old , needs a major tuneup

they to forget all that other stuff, and elaborage
what skips means.
i guess never cold does it skip.

taCH DROPS TO ZERO BUT engine not heard to stall?
if yes, electrical problems or CKP failing?
what does engine do when TACH does that, matters big time.

If you have verified that the dash temp gauge is correct by checking temp of coolant in radiator,yes your guess would be what i would change,the engine needs to have a 195degree thermostat in it.195 degrees is what the computer is programed to see as normal running temp.

Check this image...



...in the Section ZJ-Secc-8D-Ignition-Systems (page 5, fig. 10 and 11).

Good luck.

I think it is related to the cooling system, still having air in it. Make sure the heater is running/on when your running the engine. Could be a faulty ECT sensor (engine coolant temp.) but proof it out. proof it out, remove the sensor and see if there is air behind it and see if the sensor is within parameters.

check for vacuum leaks make sure throttle bodygasket is not broke and inplace and check fuel pump pressure.

Your Jeep should have a 192 or 195 degree thermostat. Do u have to add coolant once in a while? If there is no coolant loss, no overheating problem, u shouldn't have to worry about it, it could be the temp. sending unit is not accurate. If it concerns u it would probably be worth it to remove the thermostat, check the temp rating on it(it should be stamped on it). Replace w/ a new one, and see what it indicates for temp then. Good luck, let me know what u find Curt

You say you changed the cam sensor. A1391 code is a crank sensor on the top of the trans. bell housing.

possibly a head gasket going out thats what it sounds like

I had the same problem, I changed the fuel filter, put a new ignition in the column, a new module in the distributor and a new crank module, it turned out to be the fuel pump itself, go figure.