2004 DAEWOO NUBIRA gas

1F – 580IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
121. Inspect the engine control module (ECM)
grounds to make sure they are clean, tight, and
in their proper locations.
2. Inspect the vacuum lines for kinks or leaks.
Is the problem found?–Go toStep 13Go toStep 14
13Repair the electrical connections or the vacuum
lines as needed.
Is the repair complete?–System OK–
14Check the generator output voltage.
Is the generator voltage within the value specified?12–16 vGo toStep 16Go toStep 15
15Repair the generator.
Is the repair complete?–System OK–
161. Check for intermittent Exhaust Gas Recircula-
tion (EGR) valve operation.
2. Check Torque Converter Clutch (TCC) opera-
tion.
3. Repair or replace any components as needed.
Is the repair complete?–System OK–
17Repair the fuel system as needed.
Is the repair complete?–System OK–
18Replace the fuel filter.
Is the repair complete?–System OK–
19Replace the leaking or restricted fuel injectors.
Is the repair complete?–System OK–

1F – 582IENGINE CONTROLS
DAEWOO V–121 BL4
StepNo Yes Value(s) Action
141. Check the cylinder compression and valve tim-
ing.
2. Inspect the camshaft for excessive wear.
Is the problem found?–Go toStep 15Go toStep 16
15Repair or replace any engine components as need-
ed.
Is the repair complete?–System OK–
161. Check the engine control module (ECM)
grounds for being clean, tight, and in their prop-
er location.
2. Check the Exhaust Gas Recirculation (EGR)
valve for being open or partially open all the
time.
3. Check the Torque Converter Clutch (TCC) op-
eration.
4. Check the A/C system operation.
5. Check the generator output.
6. Repair the generator if the output is not within
the specified range.
Are all checks and repairs complete?12–16 vSystem 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 – 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–

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–

ENGINE CONTROLS 1F – 597
DAEWOO V–121 BL4
8. Turn the lock ring counterclockwise to clear the
tank tabs.
9. Remove the fuel pump assembly from the tank.
Installation Procedure
1. Clean the gasket mating surface on the fuel tank.
2. Position the new gasket in place.
3. Install the fuel pump into the fuel tank in the same
location as removed for ease of line and connector
installation.
4. Position the lock ring in place and turn it clockwise
until it contacts the tank stop.
5. Connect the fuel pump assembly connector.
6. Install the fuel pump outlet line.
7. Install the fuel tank return line.
8. Install the fuel pump access cover.
9. Connect the negative battery cable.
10. Perform an operational check of the fuel pump.
11. Install the rear seat. Refer to Section 9H, Seats.
FUEL FILTER
Removal Procedure
CAUTION : The fuel system is under pressure. To
avoid fuel spillage and the risk of personal injury or
fire, it is necessary to relieve the fuel system pressure
before disconnecting the fuel lines.
1. Relieve the fuel system pressure. Refer to ” Fuel
System Pressure Relief ” in this section.
2. Disconnect the negative battery cable.
3. Remove the fuel filter mounting bracket assembly
bolt.
4. Remove the fuel filter cover.
5. Disconnect the inlet/outlet fuel lines by moving the
line connector lock forward and pulling the hose off
of the fuel filter tube.

ENGINE CONTROLS 1F – 605
DAEWOO V–121 BL4
5. Disconnect the throttle cables by opening the
throttle and moving the cable through the release
slot.
6. Disconnect the vacuum hoses from the throttle
body.
7. Disconnect the throttle position (TP) sensor and the
idle air control valve connectors.
8. Disconnect the coolant hoses from the throttle
body.
9. Remove the throttle body retaining nuts.
Notice : Cover the opening of the intake manifold after re-
moving the throttle body assembly. This will prevent any
objects or debris from entering the engine which may
cause damage.
10. Remove the throttle body and discard the gasket.
11. Remove the TP sensor. Refer to ”Throttle Position
Sensor ”in this section.
12. Remove the idle air control (IAC) valve. Refer to
”Idle Air Control Valve ”in this section.
Installation Procedure
Notice : Use care in cleaning old gasket material from ma-
chined aluminum surfaces. Sharp tools may damage seal-
ing surfaces.
1. Clean the gasket mating surface on the intake man-
ifold.
Notice : The throttle body may be cleaned in a cold immer-
sion–type cleaner following disassembly. The TP sensor
and the idle air control valve should not come in contact
with any solvent or cleaner, as they may be damaged.
2. Clean the throttle body.
3. Install the TP sensor. Refer to ” Throttle Position
Sensor ”in this section.
4. Install the IAC valve. Refer to ”Idle Air Control Valve
” in this section.
5. Install the throttle body assembly with a new gasket
to the intake manifold.
6. Install the throttle body retaining nuts.
Tighten
Tighten the throttle body retaining nuts to 10 NSm (89
lb–in).