ignition DAEWOO LACETTI 2004 Service Repair Manual

ENGINE CONTROLS 1F – 577
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
101. Check the fuel injector driver circuit.
2. Disconnect all of the fuel injector harness con-
nectors at the fuel injectors.
3. Connect an injector test light between the har-
ness terminals of each fuel injector connector.
4. Note the test light while cranking the engine.
Does the test light blink at all connectors?–Go toStep 13Go toStep 11
11Check the fuel injector driver wiring harness, the
connectors, and the connector terminals for the
proper connections.
Is the problem found?–Go toStep 12Go toStep 30
12Repair the wiring harness, the connector, or the con-
nector terminal as needed.
Is the repair complete?–System OK
13Measure the resistance of each fuel injector at 68°F
(20°C). The resistance will increase slightly at high-
er temperatures.
Is the fuel injector resistance within the value speci-
fied?11.6–12.4 ΩGo toStep 15Go toStep 14
14Replace any fuel injector with a resistance that is out
of specifications.
Is the repair complete?–System OK–
15Perform an injector balance test.
Is the problem found?–Go toStep 16Go toStep 17
16Replace any restricted or leaking fuel injectors as
needed.
Is the repair complete?–System OK–
171. Check for the proper ignition voltage output for
each cylinder with a spark tester.
2. Inspect the spark plugs for cracks, wear, im-
proper gap, burned electrodes, or heavy de-
posits.
3. Inspect the ignition wires for short conditions.
4. Inspect all of the ignition grounds for loose con-
nections.
5. Inspect the powertrain control module
(PCM)/engine control module (ECM) for the
proper operation.
Is the problem found?–Go toStep 18Go toStep 19
18Correct or replace any faulty ignition components.
Is the repair complete?–System OK–
19Does the engine misfire or cut out under load or at
idle?Go to
”Ignition Sys-
tem Check”Go toStep 20
20Does the engine start, but then immediately stall?–Go toStep 21Go toStep 23
211. Remove the Crankshaft Position (CKP) sensor.
2. Inspect for faulty connections and repair as
needed.
Is the problem found?–Go toStep 22Go toStep 25
22Repair the faulty connections as needed.
Is the repair complete?–System OK–

ENGINE CONTROLS 1F – 579
DAEWOO V–121 BL4
SURGES OR CHUGGLES
Definition : 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 manualThe speedometer reading and the speed reading on the
scan tool should be equal.
Before diagnosing the symptom, check service bulletins
for updates.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
2Connect the scan tool to the Data Link Connector
(DLC).
Does the Front Heated Oxygen Sensor (HO2S1) re-
spond quickly to different throttle positions?–Go toStep 4Go toStep 3
31. Check the HO2S1 sensor for silicone or other
contaminants from fuel or use of improper
Room Temperature Vulcanizing (RTV) sealant.
2. Replace the contaminated HO2S1 sensor.
Is the repair complete?–System OK–
41. Drive 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 toStep 7Go toStep 5
5Is the long term fuel trim reading below the value
specified?–20%Go to
”Diagnostic
Aids for DTC
P0172”Go toStep 6
6Is the long term fuel trim reading above the value
specified?25%Go to
”Diagnostic
Aids for DTC
P0171”–
7Check the fuel system pressure while the condition
exists.
Is the fuel system pressure within specifications?41–47 psi
(284–325 kPa)Go toStep 8Go toStep 17
8Check the in–line fuel filter.
Is the filter dirty or plugged?–Go toStep 18Go toStep 9
9Perform an injector diagnosis.
Does the injector balance test pinpoint the problem?–Go toStep 19Go toStep 10
101. Check for proper ignition voltage output using a
spark tester.
2. Inspect the spark plugs for cracks, wear, im-
proper gap, burned electrodes, or heavy de-
posits.
Is the problem found?–Go toStep 11Go toStep 12
11Repair or replace any ignition system components
as needed.
Is the repair complete?–System OK–

ENGINE CONTROLS 1F – 581
DAEWOO V–121 BL4
LACK OF POWER, SLUGGISHNESS, OR SPONGINESS
Definition : The engine delivers less than expected power. There is little or no increase in speed when the accelerator pedal
is partially applied.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Verify the customer’s complaint.
2. Compare the performance of the customer’s
vehicle with a similar unit.
Does the problem exist?–Go toStep 3System OK
31. Inspect the air filter for excessive contamina-
tion.
2. Replace the air filter as needed.
3. Check the transaxle shift pattern and downshift
operation.
Does the transaxle operate properly?–Go toStep 4Go toStep 5
4Check the fuel system pressure.
Is the fuel system pressure within specifications?41–47 psi
(284–325 kPa)Go toStep 7Go toStep 6
5Repair the transaxle as needed.
Is the repair complete?–System OK–
6Repair the fuel system as needed.
Is the repair complete?–System OK–
7Check for a restricted fuel filter or contaminated fuel.
Is the problem found?–Go toStep 8Go toStep 9
8Repair or replace any components as needed.
Is the repair complete?–System OK–
91. Check the ignition system output for all of the
cylinders using a spark tester.
2. Check for proper ignition control operation.
Is the ignition system operating properly?–Go toStep 10Go toStep 11
101. With the engine at normal operating tempera-
ture, connect a vacuum gauge to a vacuum
port on the intake manifold.
2. Operate the engine at 1,000 rpm.
3. Record the vacuum reading.
4. Increase the engine speed to 2,500 rpm.
5. Note the vacuum reading at a steady 2,500
rpm.
Does the vacuum decrease more than the value
specified?10 kPa
(3 in. Hg)Go toStep 12Go toStep 15
11Repair or replace any ignition system components
as needed.
Is the repair complete?–System OK–
12Inspect the exhaust system for restrictions and dam-
aged or collapsed pipes.
Is the problem found?–Go toStep 13Go toStep 15
13Repair or replace any components as needed.
Is the repair complete?–System OK–

1F – 584IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
11Replace any restricted or leaking fuel injectors.
Is the repair complete?–System OK–
12Check the fuel system pressure after a cold start or
during moderate or full throttle acceleration.
Is the fuel pressure within specifications?41–47 psi
(284–325 kPa)Go toStep 14Go toStep 13
13Repair the restriction in the fuel system or replace
the faulty fuel pump.
Is the repair complete?–System OK–
141. Check for faulty ignition wires.
2. Inspect for fouled spark plugs.
3. Check the ignition system output on each cylin-
der with a spark tester.
Is the problem found?–Go toStep 15Go toStep 16
15Repair or replace any ignition components as need-
ed.
Is the repair complete?–System OK–
161. Check the generator output voltage.
2. Repair or replace the generator if the generator
output is less than the value specified.
3. Check the Exhaust Gas Recirculation (EGR)
valve operation.
Are all checks and needed repairs complete?12–16 vSystem OK–
CUTS OUT, MISSES
Definition : This Involves a steady pulsation or jerking that follows engine speed, usually more pronounced as engine load
increases. The exhaust has a steady spitting sound at idle or low speed.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
2Check the ignition system output voltage for all of the
cylinders using a spark tester.
Is spark present on all of the cylinders?–Go toStep 3Go to
”Ignition Sys-
tem Check”
31. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy de-
posits.
2. Check the resistance of the ignition wires. Re-
place any ignition wires that have a resistance
greater than the value specified.
Is the problem found?3,000 ΩGo toStep 4Go toStep 5
4Repair or replace any components as needed.
Is the repair complete?–System OK–
5With 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 toStep 6Go toStep 7
6Replace the ignition wires.
Is the repair complete?–System OK–

1F – 586IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
171. 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 toStep 18–
181. Inspect the routing of the ignition wires.
2. Inspect all of the ignition system grounds.
3. Correct the routing or repair the ground con-
nections as needed.
Are all checks and needed repairs complete?–System OK–

ENGINE CONTROLS 1F – 587
DAEWOO V–121 BL4
POOR FUEL ECONOMY
Definition : Fuel economy, as measured by an actual road
test, is noticeably lower than expected. Also, fuel econo-
my 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 questions: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.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Inspect the air filter for excessive contamina-
tion.
2. Inspect for fuel system leaks.
Are all needed checks complete?–Go toStep 3–
31. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy de-
posits.
2. Replace any faulty spark plugs.
3. Inspect the ignition wires for cracking, hard-
ness, and proper connections.
Are all needed checks and repairs complete?–Go toStep 4–
41. 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 toStep 5–
51. Check the transaxle shift pattern. Ensure all
transaxle gears are functioning.
2. Check the Torque Converter Clutch (TCC) op-
eration with a scan tool. The scan tool should
indicate rpm drop when the TCC is command-
ed on.
3. Check for proper calibration of the speedome-
ter.
4. Check the brakes for dragging.
5. Check the cylinder compression.
6. Repair, replace, or adjust any components as
needed.
Are all checks and needed repairs complete?–System OK–

1F – 590IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
221. Check the ignition system output voltage for all
of the cylinders using a spark tester.
2. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy de-
posits.
3. Inspect the ignitionwires for cracking, hard-
ness, or improper connections.
4. Replace any ignition wires with a resistance
over the value specified.
Is the problem found?3,000 ΩGo toStep 23Go toStep 24
23Repair or replace any ignition system components
as needed.
Is the repair complete?–System OK–
241. Inspect for vacuum leaks.
2. Check for proper Positive Crankcase Ventila-
tion (PCV) operation.
3. Check the Idle Air Control (IAC) valve opera-
tion.
4. Inspect the ECM ground connections.
Is the problem found?–Go toStep 25Go toStep 26
25Repair or replace any components as needed.
Is the repair complete?–System OK–
261. Check the Exhaust Gas Recirculation (EGR)
valve for proper operation.
2. Inspect the battery cables and the ground
straps for proper connections.
3. Check the generator voltage output. Repair or
replace the generator if the voltage output is
not within the value specified.
Is the problem found?12–16 vGo toStep 27Go toStep 28
27Repair or replace any components as needed.
Is the repair complete?–System OK–
281. Inspect for broken engine mounts.
2. Check for proper valve timing.
3. Perform a cylinder compression test.
4. Inspect for bent pushrods, worn rocker arms,
broken or weak valve springs, and a worn cam-
shaft.
5. Perform repairs as needed.
Are all of the checks and needed repairs complete?–System OK–

ENGINE CONTROLS 1F – 591
DAEWOO V–121 BL4
EXCESSIVE EXHAUST EMISSIONS OR ODORS
Definition : A vehicle fails an emission test. The vehicle
has an excessive rotten egg smell.Important : Excessive odors do not necessarily indicate
excessive emissions.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Run the engine until it reaches operating tem-
perature.
2. Perform an emission test.
Does the vehicle pass the emission test?–System OKGo toStep 3
31. Connect the scan tool to the Data Link Con-
nector (DLC).
2. Road test the vehicle.
3. Monitor the long term fuel trim memory.
Is the long term fuel trim memory within the value
specified?–20–25%Go toStep 6Go toStep 4
4Is the long term fuel trim memory below the value
specified?–20%Go to
”Diagnostic
Aids for DTC
P0172”Go toStep 5
5Is the long term fuel trim memory above the value
specified?25%Go to
”Diagnostic
Aids for DTC
P0171”–
61. Check for a properly installed fuel cap.
2. Check the fuel system pressure.
3. Perform an injector balance test.
Is the problem found?–Go toStep 7Go toStep 8
71. Repair or replace any fuel system components
as needed.
2. Perform an emission test.
Does the vehicle pass the emission test?–System OK–
81. Check the ignition system for proper operation.
2. Inspect the spark plugs for excessive wear,
insulation cracks, improper gap, or heavy de-
posits.
3. Check the ignition wires for cracking, hardness,
or improper connections.
Is the problem found?–Go toStep 9Go toStep 10

1F – 592IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
91. Repair or replace any ignition system compo-
nents as needed.
2. Perform an emission test.
Does the vehicle pass the emission test?–System OK–
101. Inspect for vacuum leaks.
2. Inspect the catalytic converter for contamina-
tion.
3. Inspect for carbon buildup on the throttle body
and the throttle plate and inside the engine.
Remove with a top engine cleaner.
4. Check the Exhaust Gas Recirculation (EGR)
valve to make sure it opens.
5. Check for proper Positive Crankcase Ventila-
tion (PCV) operation.
Are all checks and needed repairs complete?–System OK–
DIESELING, RUN–ON
Definition : An engine continues to run after the ignition switch is turned OFF.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
2Does the engine run smoothly after the ignition
switch is turned OFF?–Go toStep 3Go toStep 4
31. Check the ignition switch and the ignition
switch adjustment.
2. Replace the ignition switch if needed.
Is the repair complete?–System OK–
41. Check the evaporative emission system.
2. Check for leaking fuel injectors.
3. Check the Idle Air Control (IAC) valve opera-
tion.
4. Inspect for vacuum leaks.
5. Check for the proper base idle setting.
Are all checks and repairs complete?–System OK–

ENGINE CONTROLS 1F – 593
DAEWOO V–121 BL4
BACKFIRE
Definition : Fuel ignites in the intake manifold, or in the ex-
haust system, making a loud popping noise.Important : Before diagnosing the symptom, check ser-
vice bulletins for updates.
Step
ActionValue(s)YesNo
1Were the Important Preliminary Checks performed?–Go toStep 2Go to
”Important Pre-
liminary
Checks”
21. Inspect for crossed or crossfiring ignition wires.
2. Check the ignition system output voltage for all
cylinders using a spark tester.
3. Inspect the spark plugs for excessive wear,
burned electrodes, improper gap, or heavy de-
posits..
Is the problem found?–Go toStep 3Go toStep 4
3Repair or replace any ignition system components
as needed.
Is the repair complete?–System OK–
41. Check the fuel system operation.
2. Check the fuel injectors by performing an injec-
tor diagnosis.
Is the problem found?–Go toStep 5Go toStep 6
5Repair or replace any fuel system components as
needed.
Is the repair complete?–System OK–
61. Inspect the Exhaust Gas Recirculation (EGR)
gasket for a leak or a loose fit.
2. Check the EGR valve for proper operation.
3. Inspect the intake manifold and the exhaust
manifold for a casting flash.
Is the problem found?–Go toStep 7Go toStep 8
7Repair or replace any components as needed.
Is the repair complete?–System OK–
81. Inspect the timing belt for proper installation
and tension.
2. Check the engine compression.
3. Inspect the intake manifold gasket and the ex-
haust manifold gasket for leaks.
4. Check for sticking or leaking valves.
5. Repair or replace any components as needed.
Are all checks and corrections complete?–System OK–