First, i got a bad MAP sensor code, so I replaced it hoping that it would alleviate my problems. But it didn't. My jeep barely runs, the RPMS when in Park or Neutral are ok, but it still misfires and sputters. In reverse or drive, my rpms drop to 100-150. The gas pedal becomes unresponsive and it won't move at all. I've replaced the MAP sensor, crankshaft position sensor, fuel filter, cap and rotor and throttle pos. sensor. What else could this be? PLEASE HELP
SOURCE: 98 jeep starts cold sputters, no power
the p0171 code is for a fuel system lean code......possible causes are a cracked exhaust manifold.....bad o2 sensor...bad coolant temp sensor fuel pump.....lean fuel can cause the other codes you have for misfires
SOURCE: My 1996 Jeep Cherokee Sport dies or will not start when hot.
Sounds like the ignition coil is getting bad.
SOURCE: 93 jeep grand cherokee. Starts and idles ok.
Being injected, the control system varies fuel quantity and does not directly regulate air flow. Therefore, having black soot on plugs tells you that there is too much fuel going into the engine. The O2 sensor tends to react to, more than control that. Missing can be the result of plug fouling. Backfire may be the result of a too rich fuel mix permitting unburned fuel to enter the hot exhaust where it re-ignites.
Where I would look first in your case is to the manifold air temp sending unit and the coolant temp sender as well. If either or both are out of range the computer may "think" it is running a cold engine and therefore adding additional fuel for cold start up,and not switching to normal run mode when the engine reaches operating temp. Once the plugs foul the engine will continue to run poorly regardless of other conditions. You can test each component individually using either chilton or haynes manual as a guide. You will need a decent digital multi-meter to do the tests.
You can also have a code test done at most major parts stores, but often if sensors are not bad enough to set a code but together are causing a problem, you may not see anything except the O2 sensor.
There are other possible causes such as worn out injectors, but most often that won't happen in all cylinders at the same time. Do testing first, correct whatever you find and then make sure plugs are clean. If after running, the O2 sensor continues to register a fault, then replace it.
Good luck...any further questions are welcome and don't forget to rate answers!!!
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