2000 Pontiac Grand Am Misfires on 3 cylinders

172,000 MILES • 6 CYL • 2WD • AUTOMATIC
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TREFLIP98
  • MEMBER
  • 2 POSTS
I have a 2000 Pontiac Grand Am Se with 172,000 miles. It has a misfire on 3 cylinders. At idle it runs rough and low. As I accelerate more it seems to be much smoother. Also I get horrible gas mileage when it's supposed to get 20-32 mpg. I've replaced the plugs, wires, coils, and the ignition module. It also shows no signs of a leaking or blown head gasket. Could it be the fuel injectors or computer?
Jul 5, 2009 at 7:37 PM
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MMPRINCE4000
  • ✓Experienced Mechanic
  • 8,548 POSTS
Have PCM scanned at most autoparts stores for free.

Report any codes. Other sensors that are out of range will cause a rich mixture and misfires, coolant sensor for example.

You also could have a clogged CAT.
Jul 6, 2009 at 1:27 AM
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