Acceleration - Isuzu 2000 Trooper Workshop Manual

Diagnostic Trouble Code (DTC) P1171 Fuel System Lean During Acceleration
Circuit Description
The powertrain control module (PCM) internal circuitry
can identify if the vehicle fuel system is capable of
supplying adequate amounts of fuel during heavy
acceleration (power enrichment). The PCM monitors the
voltage of the oxygen sensor during power enrichment.
When a power enrichment mode of operation is
requested during "closed loop" operation (by heavy
acceleration), the PCM will provide more fuel to the
engine. Under these conditions the PCM should detect a
"rich" condition (high oxygen sensor voltage). If this "rich"
exhaust is not detected at this time, a DTC P1171 will set.
A plugged fuel filter, restricted fuel line, restricted in-tank
filter or defective fuel pump can prevent adequate
amounts of fuel from being supplied during power
enrichment mode.
Conditions for Setting the DTC
D No related DTCs.
D Engine is operating in "closed loop power enrichment"
mode for 3 seconds.
D Engine coolant temperature is above 60°C (140°F).
D While in "power enrichment" mode the oxygen sensor
voltage remains below 400 mV for 3 seconds.
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Action Taken When the DTC Sets
D The PCM will illuminate the malfunction indicator lamp
(MIL) the first the fault is detected.
D The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
D A history DTC P1171 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P1171 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
D A restricted fuel filter or fuel line, restricted in-tank filter,
or a defective fuel pump may supply adequate
amounts of fuel at idle, but may not be able to supply
enough fuel during heavy acceleration.
D Water or alcohol in the fuel may cause low HO2S
voltage during acceleration.
D Check for faulty or plugged fuel injector(s).
D Check for low fuel.
6E–413
D06RY00175