The oxygen sensor is sensing a lean condition and is compensating by enrichening the fuel trim. Possible causes:
1. Vacuum leak. Check all vacuum lines and connections (how is the idle?).
2. Pull off the intake hose and check the MAF screen for obstruction.
3. Check throttle body, EGR and pipe, and intake for leaks.
4. Check the PCV for proper operation i.e. it rattles when shaken.
5. Check exhaust for damage and leaks before the first oxygen sensor.
6. Check that the O2 sensor is properly seated and the wiring undamaged.
The other steps involve having the scanner hooked up and checking fuel trim, idle air control solenoid and MAF (mass air flow) sensor.
Try those out and let us know how it went. Concentrate on having a good look around the intake including the injectors and throttle. Good luck.
1992 Bonneville SSEi
White, grey Leather interior.
Tinted windows and blackouts on headlights.
Custom high flow exhaust, Everything replaceable - DONE
300 000 kms original engine, tranny 2 rebuilds.
Playboy Bunnies Embossed in Tint. Oh Yah!
Ever Seen a Polar Bear in a Snow Storm?