Engine Performance problem
2003 Cadillac Deville V8 Front Wheel Drive Automatic
mechanic changed mass air flow sensor twice ( rebuilt part), works for hour, then back to poor running, mpg, etc. His hand held meter says Mass air flow sensor problem, and right and left fuel bank. Dealer says need OEM not rebuilt part. What do you the expert think?
My opinion is, you have an air leak after the mass airflow sensor. This would explain the lean condition on both banks. Look for a split plenum boot between the intake, and throttle housing. There aren't many vacuum sources on this engine for leaks to occur. The MAF is probably having the finger pointed at it, but in reality, it sounds like unmetered air is entering the engine.