2005 Chevrolet Trailblazer Running hard around 50 and 55

Tiny
BMCRAIG97
  • MEMBER
  • 2005 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 139,000 MILES
My trailblazer is driving me nuts! The trailblazer seems to be missing at around 50 55. The car shacks and then will smooth out. I have flushed and changed transmission filter. Flushed and changed diff fluid. Also cleaned throttle body changed air filter when I was getting a p0171 code. Reset check engine light after cleaning throttle body and filter. I have been driving it around for around a hour and check engine light does not come on. But still runs very rough at 55 and up a hill at 55. It's the wife's car and she has the kids most of the time don't know what else to do. Anything at this point would help.
Sunday, February 2nd, 2014 AT 3:18 PM

4 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Clean the throttle plate on both sides and check fuelpressure it may be low. Auto parts rent a gauge
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Sunday, February 2nd, 2014 AT 3:47 PM
Tiny
BMCRAIG97
  • MEMBER
  • 3 POSTS
Ok thanks. Yeah I pulled throttle body all the way out and cleaned. I will stop by auto store in morning to get the gauges. If it low on pressure what does that mean?
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Sunday, February 2nd, 2014 AT 3:51 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
It means your fuel pump is probably shot or on it's way. Pressure should be 50-57 psi key on engine off
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Sunday, February 2nd, 2014 AT 3:56 PM
Tiny
BMCRAIG97
  • MEMBER
  • 3 POSTS
Ok thank you I will check it when I get off work tomorrow. Thanks for the help I will let you know what I find.
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Sunday, February 2nd, 2014 AT 3:59 PM

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