1999 Pontiac Grand Prix map sensor

1999 PONTIAC GRAND PRIX
75,000 MILES • 6 CYL • FWD • AUTOMATIC
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TRASHMAN2733
  • MEMBER
  • 1 POST
have a trouble code .missfire detected #3 and #6 (only up hill or 70 +mph.)changed coils and board.wires are new
scanner reads 9 in vacum ,gauge reads 20..
replaced map sensor ,same problem .voltage good,tps works ,recent tune-up. any ideas thanks joe
Dec 19, 2007 at 10:53 AM
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BLACKOP555
  • ✓Experienced Mechanic
  • 10,386 POSTS
check spark plug gaps, and clean the MAF sensor and also run some fuel injector and valve cleaner through the gas!
Dec 19, 2007 at 12:01 PM
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