'97 gc backfires/hesitates

[mtracy94]

97 grand cherokee with 117K...recurring shutdown and rough idle problems

have already had 2 coils and a shutdown valve replaced...then the crankshaft sensor...then most recently had my software 'flashed'

it still occasionally cuts off when idling (almost always when stopped at a light or stop sign) ... then the other night it was actually backfiring on the highway when i tried to accelerate, it almost felt like the engine turned off because hitting the gas did nothing

that same night it actually shut off a couple times but always restarted fine...please, any suggestions would be very helpful as the jeep shop can't get the car to "act up"

thanks!

[dksob81]

check the throttle Position sensor, "it almost felt like the engine turned off because hitting the gas did nothing" - sounds like a bad TPS. I have instructions for testing the TPS if u need them let me know

Joe [email protected]

[mtracy94]

thanks joe ... could the TPS also cause the car to cut off when idling, or soon after starting? i've read elsewhere on these boards that the O2 sensor could have something to do with the rough idling...

[89ltd]

Originally Posted by mtracy94

97 grand cherokee with 117K...recurring shutdown and rough idle problems

have already had 2 coils and a shutdown valve replaced...then the crankshaft sensor...then most recently had my software 'flashed'

it still occasionally cuts off when idling (almost always when stopped at a light or stop sign) ... then the other night it was actually backfiring on the highway when i tried to accelerate, it almost felt like the engine turned off because hitting the gas did nothing

that same night it actually shut off a couple times but always restarted fine...please, any suggestions would be very helpful as the jeep shop can't get the car to "act up"

thanks!

I would take a close look at the egr valve and or egr valve solanoid. An egr valve opening to soon will cause hesitation and the odd back fire as well.

[dksob81]

the EGR TRANSDUCER could cause the rough idle as well, but wouldn't cause it to stall, I think 89 has a good point, maybe it's time to take the EGR Valve out and clean the port (EGR and INTAKE).

No, the TPS wouldn't cause the jeep to stall, but it would cause it to idle hi, lo, hi, lo, etc.

If there was a problem with the O2 Sensor the PCM would pick it up immediately (CHECK ENGINE light).

how often does the jeep shutdown?

as for the rough idle go over all the vacuum lines and make sure none of them are leaking also check the Intake Manifold and throttle Body for leaks around the gasket. I would also clean out the throttle body and all the ports on it and the Intake.

[mtracy94]

it really doesn't shut down all that often...maybe 1-2 per week at most
(certainly enough to be annoying/unsafe)

only tends to shut down either right after starting or when stopped at a light or stop sign

[dksob81]

when was the last time the plugs were changed (plugs and wires). could be a faulty Idle Air control valve. or Leak in Throttle Body and/or Intake Manifold.
Have u had the injectors cleaned (or used any injector/fuel system treatment)? this may help both the Stalling and Idle.