2001 Cadillac Deville Left ans right banks running lean

Tiny
RACARRAS
  • MEMBER
  • 2001 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 128,000 MILES
Trouble code PO171 and P0174 keep coming up. I checked for vacuum leaks and have changed the Mass Air Flow Sensor but every time the "Service Engine Soon" light is reset it will only go about 30 miles before coming back on. The car runs fine but at idle the engine is always hunting for the correct idle speed going between ~600 and 800rpms. Any suggestions would be greatly appreciated. Thanks You.
Saturday, March 21st, 2009 AT 2:11 PM

1 Reply

Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
High probability that the plenum boot has a split in it causing a vacuum leak. The split usually occurs around the bottom, and can be a bit difficult to isolate. The boot is between the intake, and aluminum crossover.
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Monday, March 30th, 2009 AT 9:55 PM

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