1997 Chevy Van

1997 CHEVROLET VAN
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RON2CHRIS
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1997 Chevy Van 142000 miles

My car bucks on and off. It feels like its revving and then slowing down. The speedometer stays at about 30 mph even if I am going faster. Can you tell me what might be wrong?
Jun 22, 2009 at 5:57 AM
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RASMATAZ
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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
Jun 22, 2009 at 7:09 AM