Daewoo Nubira User Manual page 574

ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING
The engine runs unevenly at idle. If the condition is
bad enough, the vehicle may shake. Also, the idle
varies in rpm (called "hunting"). Either condition may
be severe enough to cause stalling. The engine idles
at incorrect idle speed.
Important : Before diagnosing the symptom, check ser-
vice bulletins for updates.
Step
1 Were the Important Preliminary Checks performed?
2
1. Connect the scan tool to the Data Link Con-
nector (DLC).
2. Monitor the Oxygen Sensor (O2S) reading at
different throttle positions.
Does the O2S sensor change quickly from rich to
lean at the different throttle positions?
3 Check the O2S sensor for contamination from fuel
or improper use of Room Temperature Vulcanizing
(RTV) sealant.
Is the O2S sensor contaminated?
4 Replace the contaminated O2S sensor as needed.
Is the repair complete?
5
1. Check for a sticking throttle shaft or binding
throttle linkage that may cause incorrect
Throttle Position (TP) sensor voltage.
2. Check the TP sensor voltage reading with the
throttle closed.
Is the TP sensor voltage within the value specified?
6
1. Check the Engine Coolant Temperature (ECT)
sensor voltage reading using the scan tool.
2. Compare the ECT reading with the ambient
temperature when the engine is cold.
Does the ECT temperature reading differ from the
ambient temperature by more than the value speci-
fied?
7 Check for high resistance in the ECT sensor circuit
or the sensor itself.
Is the problem found?
8 Replace the ECT sensor or repair the circuit as
needed.
Is the repair complete?
9 Check the Manifold Absolute Pressure (MAP) sen-
sor for response and accuracy.
Is the problem found?
10 Replace the MAP sensor or repair the MAP sensor
circuit as needed.
Is the repair complete?
DAEWOO V–121 BL4
Action
ENGINE CONTROLS 1F – 371
Value(s) Yes
Go toStep 2
Go toStep 5
Go toStep 4
System OK
0.4–0.8 v Go toStep 6
5³F (3³C) Go toStep 7
Go toStep 8
System OK
Go toStep 10
System OK
No
Go to"Impor-
tant Preliminary
Checks"
Go toStep 3
Go toStep 5
Go to"Diagnos-
tic Aids for
DTC P0123"
Go toStep 9
Go toStep 9
Go toStep 11