2003 Chevy Trailblazer Hesitates and bucks

Tiny
ICTHEUSA
  • MEMBER
  • 2003 CHEVROLET TRAILBLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 76,000 MILES
Only when the engine is cold my trailblazer runs very rough. It barely makes it up a hill. Once the engine warms up the car runs fine. I have recently had the car tuned up and the problem still exists. I was told that it could be the computer. Is this possible?
Wednesday, June 24th, 2009 AT 6:56 AM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Could be the computer

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
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Wednesday, June 24th, 2009 AT 6:59 AM

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