1999 GMC Sierra Truck won't excellerate?

Tiny
JACKINTEHACHAPI2
  • MEMBER
  • 1999 GMC SIERRA
  • V8
  • 4WD
  • AUTOMATIC
  • 140,000 MILES
Seems to be a problem with a rebuilt transmisson. When climbing up a grade the truck won't excellerate. Seems to be in some kind of safe mode and will only go around 20 mph. Eng will not rev up past 2000 rpm?
I replaced the fuel pump, fuel filter, throttle position sensor.
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Friday, October 31st, 2008 AT 10:53 AM

3 Replies

Tiny
MERLIN2021
  • EXPERT
How does it rev when it's in neutral? Does it seem to be a plugged converter? Or is the engine smooth and just not moving? Let me know about the revving in neutral.
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Friday, October 31st, 2008 AT 11:28 AM
Tiny
JACKINTEHACHAPI2
  • MEMBER
It revs but not like it should, also needed to mention this all starts when the transmission fails to shift then the rpm stay's at 2000 rpm and will not accelerate.
I finally got 2 fault codes to read. One code was (p0131) say's 02 Sensor Circuit Low Volts (Bank 1 Sensor 1) The 2nd code (p0300) say's Random/Mulitple Cylinder Misfire Detected. This truck has four 02 sensors. 1 in front of the converter, and 1 in back on both sides (2 converters). Do you know which sensor is the one noted in the fault code. They cost around $90.00 bucks each.
I was also told the mass air sensor may cause this problem? Is this probable.
I am repleacing the spark plugs, MAP sensor, & PVC valve to see if that helps.
If there is an internal electrical problem in the transmission causing not to shift, would there be a fault code reading?
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Saturday, November 1st, 2008 AT 2:07 PM
Tiny
MERLIN2021
  • EXPERT
Test the 02 sensor, and fuel pressure:
http://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.
http://www.2carpros.com/affiliate/uid/merlin2021_1
Tools available here!
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Saturday, November 1st, 2008 AT 2:45 PM

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