Decel Fuel Cut-Off (Dfco) - Daewoo CIELO EURO III Manual

1F – 187 ENGINE CONTROLS
OXYGEN (O2) SENSOR RICH IN DECEL FUEL CUT–OFF (DFCO)
System Description
The Oxygen Sensor (O2S) varies the voltage within a
range of about 1 volt if the exhaust is rich, down through
about 0.10 volts if the exhaust is lean.
In internal circuitry of the Engine control Module (ECM)
can identify if the vehicle fuel system is capable of cutoff
amount of the fuel supply during deceleration. When a
Decel Fuel Cut-off (DFCO) mode of operation is re-
quested during Closed Loop operation, the ECM will cut-
off the fuel supply to the engine. Under these conditions
the ECM should detect a lean condition. If the ECM de-
tect a rich condition at this time, Diagnostic Trouble
Code (DTC) P1167 will set. Damaged fuel pressure reg-
ulator and faulty injector will be the cause of this DTC.
Conditions For Setting The DTC
In DFCO mode.
Engine coolant temperature is greater than 60 C
(140 F).
System voltage is greater than 10 volts.
Engine run time is greater than 60 seconds.
No related malfunctions (See P0131).
3 seconds delay after in DFCO mode.
Action Taken When The DTC Sets
The Malfunction Indicator Lamp (MIL) will illuminate.
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.
DIAGNOSTIC TROUBLE CODE (DTC) P1167
(1.5L SOHC)
Conditions For Clearing The DTC
The MIL will turn off after four consecutive ignition
cycles in which the diagnostic runs without a fault
within the freeze frame conditions that the DTC failed.
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
The DTC P1167 or rich exhaust is most likely caused by
one of the following items:
Leaking injector – A leaking or malfunctioning injector
can cause the system to go rich causing a DTC
P0132.
Pressure regulator – Check for a leaking fuel pres-
sure regulator diaphragm by checking for the pres-
ence of liquid fuel in the vacuum line to the regulator.
Test Description
The number(s) below refer to specific step(s) on the
diagnostic table.
1. 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.
5. The replacement ECM must be reprogrammed. Re-
fer to the least Techline procedure for ECM repro-
gramming.
DAEWOO T-154 BL2,3