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Working on a 1999 Lumina with a 3.1L.
The belt tensioner is jumping, and the idle and voltage is surging.
It doesn't surge in Open Loop, only Closed Loop.
Used carb cleaner and couldn't find any vacuum leaks.
LTFT is close to -10 at idle when in closed loop (rich).
The plugs were white (lean).
Does this indicate a bad o2 sensor?
The belt tensioner is jumping, and the idle and voltage is surging.
It doesn't surge in Open Loop, only Closed Loop.
Used carb cleaner and couldn't find any vacuum leaks.
LTFT is close to -10 at idle when in closed loop (rich).
The plugs were white (lean).
Does this indicate a bad o2 sensor?