2000 Chevy Astro hesitation under load

TUNES1561

MEMBER
2000 CHEVROLET ASTRO
6 CYL
2WD
AUTOMATIC
196,322 MILES

My 2000 chevy astro has serious hesitation problems when accelerating. I'ts had a full tune-up with no improvemt. The scanner shows misfire on cylinder #4 @ idle and misfire on all cylinders @ load. I've replaced the coil, fuel pump, spider web injector system and have had a compression test with the results of 180 lbs. Of pressure per cylinder, the MAF sensor is working fine. What am I missing? HELP PLEASE. Thanks, Terri

Tuesday, November 24th, 2009 AT 12:54 AM

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Oxygen sensor
Catalytic converter
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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Tuesday, November 24th, 2009 AT 2:14 AM