Lack of power when accelerating

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BeckyThe tj

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Joined
Jan 21, 2023
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5
Location
South Carolina
I have a 2001 wrangler 5-speed manual and the 4.0 and it stutters and struggles to accelerate under load, this happens almost constantly and almost makes the jeep undrivable. It refuses to go past 3k rpm while driving and cannot get past 50mph. When idle it will rev normally and there is no stuttering I have changed the TPS and MAP (Manifold adequate pressure) sensors as well as the crankshaft position sensor with Mopar parts. Those sensors did not make a difference at all. The Camshaft position sensor has been changed as well but with the Napa brand. There is no check engine light. All of the spark plugs were replaced about 2000 miles ago. The jeep starts right up fine but won't drive.

I have seen some threads saying that it could be the upstream O2 sensors and I had an OBII reader connected while driving and they were reading anywhere from 0.040 to 0.920 volts for both of the upstream O2 sensors. I have also seen that it could be the PCM itself that is causing the issue but I replaced my PCM about a year ago for an issue where the jeep would stall while driving and then refuse to start. So I'm hoping that my PCM is not the issue. The jeep is running a little rich on fuel I can smell gas from the exhaust if I come to a stop after driving and it gets about 9mpg on 35s with 4.88 gears and ARB lockers, and I think it should be a little bit better than that at least. This makes me think that it could have something to do with the fuel pump or relay.

Any help will be greatly appreciated.
 
BeckyThe tj said:
I have a 2001 wrangler 5-speed manual and the 4.0 and it stutters and struggles to accelerate under load, this happens almost constantly and almost makes the jeep undrivable. It refuses to go past 3k rpm while driving and cannot get past 50mph. When idle it will rev normally and there is no stuttering I have changed the TPS and MAP (Manifold adequate pressure) sensors as well as the crankshaft position sensor with Mopar parts. Those sensors did not make a difference at all. The Camshaft position sensor has been changed as well but with the Napa brand. There is no check engine light. All of the spark plugs were replaced about 2000 miles ago. The jeep starts right up fine but won't drive.

I have seen some threads saying that it could be the upstream O2 sensors and I had an OBII reader connected while driving and they were reading anywhere from 0.040 to 0.920 volts for both of the upstream O2 sensors. I have also seen that it could be the PCM itself that is causing the issue but I replaced my PCM about a year ago for an issue where the jeep would stall while driving and then refuse to start. So I'm hoping that my PCM is not the issue. The jeep is running a little rich on fuel I can smell gas from the exhaust if I come to a stop after driving and it gets about 9mpg on 35s with 4.88 gears and ARB lockers, and I think it should be a little bit better than that at least. This makes me think that it could have something to do with the fuel pump or relay.

Any help will be greatly appreciated.
Click to expand...

Take the upstream o2s out and get a camera and look at the cats,also check fuel pressure
 
It does sound like you could (and likely) have a bad O2 sensor, especially that you are detecting the aroma of gasoline which indicates the fuel mixture is too rich. Personally I'd replace them but make sure to ONLY install either NTK, NGK, or Mopar O2 sensors and all of those are made by NTK.

Yours has four O2 sensors and all can affect the air/fuel mixture.
Bank 1 Upstream NTK 23139
Bank 1 Downstream NTK 23142
Bank 2 Upstream NTK 13664
Bank 2 Downstream NTK 23141

They're available at https://www.rockauto.com/en/catalog...23,exhaust+&+emission,oxygen+(o2)+sensor,5132

This shows their locations.

O2-sensor-locations.jpg
 
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