ENGINE CONTROLS 1F – 361
DAEWOO V–121 BL4
Step NoYesValue(s)Action
23
1. Check for the proper valve timing.
2. Check the cylinder compression.
3. Inspect the pushrods, the rocker arms, the
valve springs, and the camshaft lobes for ex-
cessive wear.
4. Inspect the intake manifold and the exhaust
manifold passages for casting flash.
Is the problem found?
Go toStep 24 Go toStep 25
24 Repair or replace any components as needed.
Is the repair complete?
System OK
25 Check the Idle Air Control (IAC) valve operation. Re-
pair or replace components as needed.
Is the repair complete?
System OK
26 Check the base idle setting of the throttle body.
Is the repair complete?
Go toStep 27 Go toStep 28
27 Check the Throttle Position (TP) sensor circuit for
proper operation. Repair or replace components as
needed.
Is the repair complete?
System OK
28 Adjust the base idle setting to specifications.
Is the repair complete?
System OK
29 Repair the fuel system as needed.
Is the repair complete?
System OK
30 Replace the PCM/ECM.
Is the repair complete?
System OK
SURGES OR CHUGGLES
Engine power varies under steady throttle or cruise,
making it feel as if the vehicle speeds up and slows
down with no change in the accelerator pedal
position.
Important : Make sure the driver understands Torque
Converter Clutch (TCC) and A/C compressor operation as
described in the owner’s manual
The speedometer reading and the speed reading on the
scan tool should be equal.
Before diagnosing the symptom, check service bulletins
for updates.
Step Action Value(s) Yes No
1 Were the Important Preliminary Checks performed? Go toStep 2 Go to”Impor-
tant Preliminary
Checks”
2 Connect the scan tool to the Data Link Connector
(DLC).
Does the Oxygen Sensor (O2S) respond quickly to
different throttle positions?
Go toStep 4 Go toStep 3
3
1. Check the O2S sensor for silicone or other
contaminants from fuel or use of improper
Room Temperature Vulcanizing (RTV) sealant.
2. Replace the contaminated O2S sensor.
Is the repair complete?
System OK
To Next Page
