Question about 2003 Jeep Liberty

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RPM's go from 500 to 2000 sporadically and the Jeep loses speed

I'll start from the beginning:
I have a 2003 Jeep Liberty Limited, 4x2, 3.7 L V6. I bought the Jeep a month ago and at the time, the regulators for both of my rear windows were out. The windows wouldn't go down and the driver side window wouldn't stay up, like it was off track. The dealer agreed to fix this, so I took it in 3 days ago. When I got the Jeep back, the windows weren't fixed because they had ordered the wrong parts. I drove the Jeep home and left it parked until the next day.

The next day, I took my Jeep to the carwash and it stalled when I put it in park (It's an automatic.) I didn't think anything of it, until later that evening. I turned from a stop sign and it started jerking. the rpm's kept going back and forth from about 500 to 2000 and it wouldn't maintain a speed. I turned into a driveway and it stalled again.

Yesterday, I didn't have a problem until the evening. I drove around for a good part of the day, and on my way home it decided to do the jerking thing again. I was going 50 mph and when I started to go up a hill it started and the speed dropped down to 20 mph. I let off the gas for a second and the jerking stopped and I was able to drive normally again. Then the ''check engine light'' came on. Luckily, I was only about 1/2 mile from my house.

This morning, I took a trip to Autozone and had the computer checked. It showed to be either a speed sensor or the crankshaft sensor. However, the guy at Autozone recommended I take it to the dealer. I got to Jeep and the guy was really rude and wouldn't even discuss it with me unless I agreed to pay a $92 diagnostic fee.

I drove about another 30 miles and it started up again, on the highway. I was going 70 mph and it was like I slammed on the brakes. the rpm's started going crazy again and the speed dropped down to 50 mph, while it kept jerking. I got back up to speed and it kept doing the same thing. I thought I might have bought bad gas, so I filled up the Jeep with premium, and there was no improvement. I made my 30 mile drive home on the access road, going 30 mph. If I try to speed up, it boggs down and won't accelerate once I reach between 25 and 30 mph. If I stop and restart the Jeep, it takes off fine and gets up to speed fine, but it will eventually **** and slow down. And once I slow down in traffic, it won't go above 25 again. I bought a can of seafoam after all this and had the computer checked again. Unfortunately, the computer now shows that it could be a speed sensor, the crankshaft sensor, an 02 sensor, etc. I'm just trying to figure out if this is something minor, that I can figure out, or if I should go get ripped off at the dealer.

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Hi katie
dealers are a pain in the but.t we all know unfortunetly there are many things that can go wrong in an engine these days all the electronics are a nightmare and people do have to pay allot of money to get them sorted out, by what you are saying and verry good description as well i might add, it actually sounds more like the TP sensor ( throtle possitionsensor ) it wouldnt be the 02 sensor as that would not make a difference to the rpm's, nore crank sensor, speed sensor ( there are 2 of these) it might be but i would be a bit hessitant and changing it first as normally that just sends signal to the speedo ( front one, posistion1 ) and the rear one records road speed, so i cant see it being that one, i personaly would go for a test on the TP sensor as this would definatley make the symptoms you are describing, the ECM could also be a problem if this has got "dirty software" in it this could cause loads of faults, you would then need to get the ECM ( engine control moduel ) re-mapped to get it back to normal, well i think that would be just about enough to be getting on with, so first i would check out ECM, if ok the the TP, then the speed sensor....hope this helps call back if you find the fault as well as if you dont ok..

Posted on May 31, 2010

Testimonial: "Thanks! Someone else told me about the ECM, as well. Hopefully I can get it checked out tomorrow."

  • katie_rose89 May 31, 2010

    Unfortunately, it wasn't the ECM. That would have been an easy fix.


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Posted on Jan 29, 2011


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