DTC P1171: Fuel System Lean During Acceleration (SOHC): Description
WARNING: This page is about a different car, the 2002 Pontiac Sunfire, 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The Powertrain Control Module (PCM) can identify if the vehicle fuel system is capable of supplying adequate amounts of fuel during heavy acceleration. This condition is called a power enrichment mode of operation. If power enrichment is requested during a closed loop operation, the PCM will provide more fuel to the engine. Under these conditions, the PCM should detect a rich condition. If the PCM does not detect a rich exhaust at this time, DTC P1171 will set. A plugged fuel filter, or a restricted fuel line can prevent adequate amounts of fuel from being supplied during the power enrichment mode.