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brownjeff
brownjeff, ASE Certified Technician
Category: Jeep
Satisfied Customers: 13886
Experience:  17 years experience, ASE certified, dealership certified, Service Manager for 15 years,
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2000 JEEP CHEROKEE: P0171..RUN SO BAD THAT THERE WAS NO ACCELERATION

Resolved Question:

WHAT WOULD CAUSE A P0171 CODE ON A 2000 JEEP CHEROKEE AND CAUSE IT TO RUN SO BAD THAT THERE WAS NO ACCELERATION?
Submitted: 6 years ago.
Category: Jeep
Expert:  brownjeff replied 6 years ago.

Could be a map sensor, tps sensor, coolant sensor, or a fuel pressure problem. I would start with checking the fuel pressure to make sure getting enough fuel. The pressure should be around 49 psi. If lower then replace the fuel pump. If the pressure is good and no other codes I would replace the sensors in the following order......

 

1st: Engine coolant temperature sensor

2nd: Throttle position sensor (TPS)

3rd: Manifold absolute pressure sensor (MAP)

 

Customer: replied 6 years ago.
I checked the fuel pressure and it was around 50-55 psi. on my hand held scanner the freeze frame data at the time of the code map kpa 44, coolant 199 degrees f, fuel systen 1 closed.
Expert:  brownjeff replied 6 years ago.
If getting a code for the map sensor then I suggest replacing it as it is one of the possible causes for the problem you have.
Customer: replied 6 years ago.
the code i am recieving is for a system too lean bank 1, would a map sensor be intermitting? the problem started a couple of days ago it was acting like a fuel filter, when the engine became unresponsive you could pull over and wait a few mins and everything would start working as required. (no code had been present at the time) the other night the jeep lost all acceleration and was running rough. if you pressed the pedal the engine would die out. but it would idle rough. that is when the code appeared. the map kpa 44 was the map sensor reading at the time of the p0171 (system too leak). is there any way to test the map sensor befor replacing it? and also how does the throttle position sensor play a part in the code?
Expert:  brownjeff replied 6 years ago.
No good test for the map sensor short of replacing it. How the throttle position sensor plays in is that the computer uses the position of the throttle to know how much fuel to allow. If it thinks you are at idle or light throttle when really you are at heavy throttle you will not get enough fuel
Customer: replied 6 years ago.

is the any way to test the tps ohming it out?

Expert:  brownjeff replied 6 years ago.
To test the tps with the key on move the throttle and watch the output voltage it should change and be smooth as the throttle is open and closed if not then it needs to be replaced.
Customer: replied 6 years ago.
is it on a five volt referance
Expert:  brownjeff replied 6 years ago.
No 1 volt or less on the output
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