Daewoo Nubira User Manual page 575

1F – 372IENGINE CONTROLS
Step
11
1. Road test the vehicle at the speed of the com-
plaint.
2. Monitor the fuel trim reading using the scan
tool.
Is the fuel trim reading within the value specified?
12 Is the fuel trim reading below the value specified?
13 Is the fuel trim reading above the value specified?
14
1. Disconnect all of the fuel injector harness con-
nectors at the fuel injectors.
2. Connect an injector test light between the har-
ness terminals of each fuel injector connector.
3. Note the test light while cranking the engine.
Does the test light blink for all of the fuel injectors?
15
1. Repair or replace the faulty injector drive circuit
harness, the connector, or the connector termi-
nals as needed.
2. If the harness, the connectors, and the termi-
nals are OK, replace the powertrain control
module (PCM)/engine control module (ECM).
Is the repair complete?
16 Measure the resistance of each of the fuel injectors.
The resistance will increase slightly at higher tem-
peratures.
Is the resistance within the value specified?
17 Replace any fuel injectors with a resistance that is
out of specifications.
Is the repair complete?
18 Perform an injector balance test.
Is the problem found?
19 Replace any leaking or restricted fuel injectors.
Is the repair complete?
20
1. With the engine OFF, disconnect the fuel pres-
sure regulator vacuum hose.
2. Thoroughly inspect the fuel pressure regulator
vacuum port and the fuel pressure regulator
vacuum hose for the presence of fuel.
Is the problem found?
21 Replace the fuel pressure regulator as needed.
Is the repair complete?
Action Value(s) Yes
115–150 Go toStep 14
counts
115 counts Go to"Diagnos-
tic Aids for
DTC P0172"
150 counts Go to"Diagnos-
tic Aids for
DTC P0171"
Go toStep 16
System OK
11.6–12.4 Ω
Go toStep 18
System OK
Go toStep 19
System OK
Go toStep 21
System OK
No
Go toStep 12
Go toStep 13
Go toStep 15
Go toStep 17
Go toStep 20
Go toStep 22
DAEWOO V–121 BL4