I repeatedly have a code P0171 on my 1997 Oldsmobile Regency.

Question

I have replaced both upstream and downstream bank 1 oxygen sensors, the mass air flow sensor, the throttle position sensor, the idle air control valve, and the fuel filter. My mechanic says that my fuel pressure is good. I have replaced the powertrain control module and had it programmed by a dealership. I have had a smoke test done that revealed a vacuum leak from the intake manifold gasket and a cracked plenum. A new plenum and a new intake manifold kit were put on. Two additional smoke tests have not detected leaks, but still the code comes back. The car does not present a problem while running, but will occasionally sputter and stall upon start up. Any suggestions of what to check next?

Answer 1

has spark plugs/wires or ignition system been checked/replaced? Try to do fuel injector flush, could be a bad or clogged injector. Also check the PCV valve, since you could be clogged or stuck

 

possible causes:

- Intake air leaks
- Faulty front heated oxygen sensor
- Ignition misfiring
- Faulty fuel injectors
- Exhaust gas leaks
- Incorrect fuel pressure
- Lack of fuel
- Faulty Mass Air Flow (MAF) sensor
- Incorrect Positive Crankcase Ventilation (PCV) hose connection