Mechanics

CHEVY

2003 Chevrolet Impala

Engine Performance problem
2003 Chevy Impala 6 cyl Two Wheel Drive Automatic

random missfires under light load. Plugs, wires, coils are all good
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Jescobedo
August 4, 2009.



Do you have the 3.8? I have had the plastic upper plenum get a hole in them on the inside at the throttlebody coolant passage, causing coolant to leak into the intake, Have the computer scanned for misfire codes, taking note which cylinders are misfiring. If it is the upper plenum causing this it will have to be replaced. Good Luck

Tiny
Lout5369
Aug 6, 2009.