Daewoo CIELO EURO III, Manual

Page: 362 / 603

1F – 193 ENGINE CONTROLS
DAEWOO T-154 BL2,3
DIAGNOSTIC TROUBLE CODE (DTC) P1171
FUEL TRIM SYSTEM LEAN DURING POWER ENRICHMENT
System Description
The internal circuitry of the powertrain control module
engine control module (ECM) can identify if the
vehicle fuel system is capable of supplying adequate
amounts of fuel during heavy acceleration (power en-
richment). When a power enrichment mode of operation
is requested during Closed Loop operation (by heavy
acceleration), the ECM will provide more fuel to
the engine. Under these conditions the ECM
should detect a rich condition. If this rich exhaust is not
detected at this time, a DTC P1171 will set. A plugged
fuel filter or restricted fuel line can prevent adequate
amounts of fuel from being supplied during power en-
richment mode.
Conditions for Setting the DTC
No related malfuntions (see P0131).
Engine is operating in power enrichment (PE) mode.
Engine coolant temperature is greater than 60 C
(140 F).
1.5L SOHC
Air-to-fuel ratio is less than or equal to 13.5:1.
System voltage is greater than 10 volts.
Engine run time is greater than 60 seconds.
3 second delay after in PE mode.
Action Taken When the DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate
after second consecutive trip with a fail.
The ECM will record operating conditions at the
time the diagnostic fails. This information will be
stored in the freeze frame and failure records buffers.
A history DTC is stored.
Conditions for Clearing the MIL/DTC
The MIL will turn off after three (four –
1.5L SOHC) consecutive ignition cycles in which the
diagnostic runs without a fault.
A history DTC will clear after 40 consecutive warm-up
cycles without a fault.
The DTC(s) can be cleared by using the scan tool.
Diagnostic Aids
A restricted fuel filter can supply adequate amounts of
fuel at idle, but may not be able to supply enough fuel
during heavy acceleration.
Water or alcohol in fuel may cause low O2S 1 voltage
during acceleration.
Check for adequate amount of fuel in the Tank.
When the engine is idling or at steady cruise, the O2S
1 voltage should vary from between approximately
100 mv to 900 mv. During power enrichment mode,
more fuel is needed and O2S 1 should rise above
447 mv.
Check for faulty or plugged injector(s).
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Table.
1. The On-Board Diagnostic (EOBD) System Check
prompts the technician to complete some basic
checks and store the freeze frame and failure re-
cords data on the scan tool if applicable. This
creates an electronic copy of the data taken when
the malfunction occurred. The information is then
stored on the scan tool for later reference.
4. This step checks to see if the O2S 1 is operating
properly.
6. If no faults have been found at this point and no addi-
tional DTCs were set, refer to “Diagnostic Aids” in
this section for additional checks and information.