1F–290 ENGINE CONTROLS
DAEWOO M-150 BL2
DETONATION/SPARK KNOCK
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
1. Fill the fuel tank with a known good grade of
gasoline that has the octane rating of the value
specified.
2. Reevaluate the vehicle’s performance.
Does the detonation problem still exist?
91 octaneGo to Step 3System OK
3
1. Inspect for low engine coolant level.
2. Check for restricted airflow to the radiator or
restricted coolant flow.
3. Check for a faulty thermostat.
4. Check for an incorrect coolant solution.
Is the problem found?
–
Go to Step 4Go to Step 5
4
Repair or replace any cooling system components
as needed.
Is the repair complete?
–
System OK
–
5
1. Check the engine coolant temperature using the
scan tool.
2. Replace the Engine Coolant Temperature (ECT)
sensor if the resistance is not within specifications
as listed in the Diagnostic Aids for diagnostic
trouble code P0118.
Is the problem found?
–
Go to Step 6Go to Step 7
6
Replace the ECT sensor or repair the circuit as
needed.
Is the repair complete?
–
System OK
–
7
1. Check the ignition system output with a spark
tester.
2. Inspect the spark plugs for the proper heat range
and gap.
3. Check for the proper operation of the ignition
controls.
Is the ignition system operating properly?
–
Go to Step 9Go to Step 8
8
Repair or replace the ignition system components as
needed.
Is the repair complete?
–
System Ok
–
9
1. Connect the scan tool to the Data Link Connector
(DLC).
2. Road test the vehicle at the speed of the
complaint.
3. Monitor the long term fuel trim reading from the
scanner data stream.
Is the long term fuel trim reading above the value
specified?
25%
Go to
“Diagnostic Aids
for DTC P0171”
Go to Step 10
10Check the fuel system pressure.
Is the problem found?380 kPa
(55 psi)
Go to Step 11Go to Step 12
11
Repair or replace the fuel system components as
needed.
Is the repair complete?
–
System OK
–
ENGINE CONTROLS 1F–291
DAEWOO M-150 BL2
Detonation/Spark Knock (Cont’d)
StepActionValue(s)YesNo
12
1. Inspect for carbon buildup inside the engine.
2. Remove the carbon with a top engine cleaner.
Follow the instructions supplied with the product.
3. Check the basic engine parts such as the
camshaft, the cylinder head, the pistons, etc. for
excessive wear.
4. Replace any excessively worn parts.
Is the procedure complete?
–
Go to Step 13
–
13
1. Check the exhaust gas recirculation valve for
proper operation.
2. Check the air intake system for proper operation.
3. Check the torque converter clutch operation and
transaxle shift points.
4. Check the service bulletins for Programmable
Read Only Memory (PROM) updates.
5. Check the cylinder compression.
6. Repair or replace any faulty components.
Are all checks and repairs complete?
–
System OK
–
1F–292 ENGINE CONTROLS
DAEWOO M-150 BL2
HESITATION, SAG, STUMBLE
Definition: Momentary lack of response as the accelera-
tor is pushed down. This can occur at any vehicle speed.
It is usually the most severe when first trying to make the
vehicle move, as from a stop. Hesitation, sag, or
stumble may cause the engine to stall if severe enough.Important: Before diagnosing this condition, check ser-
vice bulletins for PROM updates.
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
1. Check the fuel system pressure. If the pressure is
not within the value specified, service the fuel
system as needed.
2. Inspect the Throttle Position (TP) sensor for
binding or sticking. The TP sensor voltage should
increase at a steady rate as the throttle is moved
toward Wide Open Throttle (WOT).
Is the problem found?
380 kPa
(55 psi)
Go to Step 3Go to Step 4
3Repair or replace any components as needed.
Is the repair complete?–System OK–
4
1. Check the Manifold Absolute Pressure (MAP)
sensor response and accuracy.
2. Inspect the fuel for water contamination.
3. Check the Evaporative Emission (EVAP) Canister
Purge System for proper operation.
Is the problem found?
–
Go to Step 5Go to Step 6
5Repair or replace any components as needed.
Is the repair complete?–System OK–
6
1. Disconnect all of the fuel injector harness
connectors.
2. Connect an injector test light between the
harness terminals of each fuel injector.
3. Note the test light while cranking the engine.
Does the test light blink on all connectors?
–
Go to Step 8Go to Step 7
7
1. Repair or replace the faulty fuel injector drive
harness, the connector, or the connector terminal.
2. If the connections and the harnesses are good,
replace the Engine Control Module (ECM).
Is the repair complete?
–
System OK
–
8
Measure the resistance of each fuel injector.
Is the fuel injector resistance within the value
specified (the resistance will increase slightly at
higher temperatures)?
11.6–12.4 ΩGo to Step 10Go to Step 9
9
Replace any of the fuel injectors with a resistance
that is out of specifications.
Is the repair complete?
–
System OK
–
10Perform an injector diagnosis.
Is the problem found?–Go to Step 11Go to Step 12
11Replace any restricted or leaking fuel injectors.
Is the repair complete?–System OK–
12
Check the fuel system pressure after a cold start or
during moderate or full throttle acceleration.
Is the fuel pressure within specifications?
380 kPa
(55 psi)
Go to Step 14Go to Step 13
ENGINE CONTROLS 1F–293
DAEWOO M-150 BL2
Hesitation, Sag, Stumble (Cont’d)
StepActionValue(s)YesNo
13
Repair the restriction in the fuel system or replace
the faulty fuel pump.
Is the repair complete?
–
System OK
–
14
1. Check for faulty ignition wires.
2. Inspect for fouled spark plugs.
3. Check the ignition system output on each cylinder
with a spark tester.
Is the problem found?
–
Go to Step 15Go to Step 16
15
Repair or replace any ignition components as
needed.
Is the repair complete?
–
System OK
–
16
1. Check the generator output voltage.
2. Repair or replace the generator if the generator
output is less than the value specified.
3. Check the Electric Exhaust Gas Recirculation
(EEGR) valve operation.
Are all checks and needed repairs complete?
–
System OK
–
1F–294 ENGINE CONTROLS
DAEWOO M-150 BL2
CUTS OUT, MISSES
Definition: Steady pulsation or jerking that follows en-
gine speed, usually more pronounced as engine load in-creases. The exhaust has a steady spitting sound at idle
or low speed.
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
Check the ignition system voltage output for all of
the cylinders using a spark tester.
Is spark present on all of the cylinders?
–
Go to Step 3
Go to “Ignition
System Check”
3
1. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy
deposits.
2. Check the resistance of the ignition wires.
Replace any ignition wires that have a resistance
greater than the value specified.
Is the problem found?
30000 ΩGo to Step 4Go to Step 5
4Repair or replace any components as needed.
Is the repair complete?–System OK–
5
With the engine running, spray the ignition wires with
a fine water mist to check for arcing and shorting to
ground.
Is the problem found?
–
Go to Step 6Go to Step 7
6Replace the ignition wires.
Is the repair complete?–System OK–
7
1. Perform a cylinder compression test.
2. If the compression is low, repair the engine as
needed.
3. Inspect for proper valve timing, bent pushrods,
worn rocker arms, broken or weak valve springs,
and worn camshaft lobes.
4. Inspect the intake manifold and the exhaust
manifold passages for casting flash.
Is the problem found?
–
Go to Step 8Go to Step 9
8Repair or replace any components as needed.
Is the repair complete?–System OK–
9
1. Check the fuel system for a plugged in-line fuel
filter.
2. Check the fuel system for low fuel pressure. If the
fuel pressure is below the value specified, service
the fuel system as needed.
3. Inspect for contaminated fuel.
Is the problem found?
380 kPa
(55 psi)
Go to Step 10Go to Step 11
10Repair or replace any components as needed.
Is the repair complete?–System OK–
11
1. Disconnect all of the fuel injector harness
connectors at the fuel injectors.
2. Connect an injector test light to the harness
terminals of each fuel injector connector.
3. Note the test light while cranking the engine for
each fuel injector.
Does the test light blink for all of the fuel injectors?
–
Go to Step 13Go to Step 12
ENGINE CONTROLS 1F–295
DAEWOO M-150 BL2
Cuts Out, Misses (Cont’d)
StepActionValue(s)YesNo
12
1. Repair or replace the faulty injector drive circuit
harness, the connector, or the connector terminal.
2. If the connections and the harnesses are good,
replace the Engine Control Module (ECM).
Is the repair complete?
–
System OK
–
13
Measure the resistance of each fuel injector.
Is the injector resistance within the value specified
(the resistance will increase slightly at higher
temperatures)?
11.6–12.4 ΩGo to Step 15Go to Step 14
14
Replace any fuel injectors with a resistance that is
out of specifications.
Is the repair complete?
–
System OK
–
15Perform an injector diagnosis.
Is the problem found?–Go to Step 16Go to Step 17
16Replace any restricted or leaking fuel injectors.
Is the repair complete?–System OK–
17
1. Check for electromagnetic interference.
2. Monitor the engine rpm with a scan tool.
Does the scan tool rpm change greatly with little
change in actual engine rpm?
–
Go to Step 18
–
18
1. Inspect the routing of the ignition wires.
2. Inspect all of the ignition system grounds.
3. Correct the routing or repair the ground
connections as needed.
Are all checks and needed repairs complete?
–
System OK
–
1F–296 ENGINE CONTROLS
DAEWOO M-150 BL2
POOR FUEL ECONOMY
Definition: Fuel economy, as measured by an actual
road test, is noticeably lower than expected. Also, fuel
economy is noticeably lower than it was on this vehicle
at one time, as previously shown by an actual road test.
Important: Driving habits affect fuel economy. Check
the owner’s driving habits by asking the following ques-
tions:1. Is the A/C system (i.e. defroster mode) turned on all
the time?
2. Are the tires at the correct air pressure?
3. Have excessively heavy loads been carried?
4. Does the driver accelerate too much and too often?
Suggest the driver read the section in the owner’s
manual about fuel economy.
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
1. Inspect the air filter for excessive contamination.
2. Inspect for fuel system leaks.
Are all needed checks complete?
–
Go to Step 3
–
3
1. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy
deposits.
2. Replace any faulty spark plugs.
3. Inspect the ignition wires for cracking, hardness,
and proper connections.
Are all needed checks and repairs complete?
–
Go to Step 4
–
4
1. Inspect the engine coolant level.
2. Check the thermostat for being always open or for
an incorrect heat range.
3. Replace the thermostat as needed.
Are all needed checks and repairs complete?
–
Go to Step 4
–
5
1. Check the transaxle shift pattern. Ensure all
transaxle gears are functioning.
2. Check for proper calibration of the speedometer.
3. Check the brakes for dragging.
4. Check the cylinder compression.
5. Repair, replace, or adjust any components as
needed.
Are all checks and needed repairs complete?
–
System OK
–
ENGINE CONTROLS 1F–297
DAEWOO M-150 BL2
ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING
Definition: The engine runs unevenly at idle. If the condi-
tion 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 in-
correct idle speed.Important: Before diagnosing the symptom, check ser-
vice bulletins for updates.
StepActionValue(s)YesNo
1
Were the Important Preliminary Checks performed?
–
Go to Step 2
Go to
“Important
Preliminary
Checks”
2
1. Connect the scan tool to the Data Link Connector
(DLC).
2. Monitor the oxygen sensor (O2S) reading at
different throttle positions.
Does the O2S change quickly from rich to lean at
the different throttle positions?
–
Go to Step 5Go to Step 3
3
Check the O2S for contamination from fuel or
improper use of room temperature vulcanizing
sealant.
Is the O2S contaminated?
–
Go to Step 4Go to Step 5
4Replace the contaminated O2S as needed.
Is the repair complete?–System OK–
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?
0.4–0.8 VGo to Step 6
Go to
“Diagnostic
Aids for DTC
P0123”
6
1. Check the Engine Coolant Temperature (ECT)
sensor voltage reading using the scan tool.
2. Compare the ECT sensor reading with the
ambient temperature when the engine is cold.
Does the ECT sensor temperature reading differ
from the ambient temperature by more than the
value specified?
3C (5F)Go to Step 7Go to Step 9
7
Check for high resistance in the ECT sensor circuit
or the sensor itself.
Is the problem found?
–
Go to Step 8Go to Step 9
8
Replace the ECT sensor or repair the circuit as
needed.
Is the repair complete?
–
System OK
–
9
Check the Manifold Absolute Pressure (MAP)
sensor for response and accuracy.
Is the problem found?
–
Go to Step 10Go to Step 11
10
Replace the MAP sensor or repair the MAP sensor
circuit as needed.
Is the repair complete?
–
System OK
–
11
1. Road test the vehicle at the speed of the
complaint.
2. Monitor the long term fuel trim reading using the
scan tool.
Is the long term fuel trim reading within the value
specified?
–20–25%Go to Step 14Go to Step 12