Oil service DAEWOO LACETTI 2004 Service User Guide

1.4L/1.6L DOHC ENGINE MECHANICAL 1C1 – 55
DAEWOO V–121 BL4
9. Inspect the engine block deck surface for flatness
using a straight edge and a feeler gauge. Refer to
”Engine Specifications” in this section.
10. Inspect the bearing bore for concentricity and align-
ment using a bore gauge. Refer to ”Engine Specifi-
cations” in this section. If the bearing bore is be-
yond specifications, replace the engine block.
11. Inspect the engine block cylinder bore for wear,
runout, ridging and taper using a bore gauge. Refer
to ”Engine Specifications” in this section.
12. Inspect the engine block cylinder bore for glazing.
Lightly hone the cylinder bore as necessary.
Installation Procedure
1. Align the notch on the piston and the connecting
rod so that the proper sides will be facing the front
of the engine.
2. Install the piston pin guide through the piston and
the connecting rod.
3. Coat the piston pin with clean oil.
4. Install the piston pin into the opposite side of the
piston.
5. Install the piston pin into the piston and connecting
rod assembly using the piston pin service set
KM–427.
6. Select a set of new piston rings.
7. Measure the piston ring gap using a feeler gauge.
Refer to ”Engine Specifications” in this section.
8. Increase the piston ring gap by carefully filing off
excess material if the piston ring gap is below spec-
ifications.
9. Measure the piston ring side clearance using a feel-
er gauge. Refer to ”Engine Specifications’’ in this
section.
10. If the piston ring is too thick, try another piston ring.
11. If no piston ring can be found that fits to specifica-
tions, the piston ring may be ground to size with
emery paper placed on a sheet of glass.

SECTION : 1C2
1.8L DOHC ENGINE MECHANICAL
CAUTION : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool
or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help
prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.
TABLE OF CONTENTS
SPECIFICATIONS1C2–2 . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Specifications 1C2–2. . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifcations 1C2–4. . . . . . . . . .
SPECIAL TOOLS1C2–6 . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1C2–6. . . . . . . . . . . . . . . . . . . . . . .
COMPONENT LOCATOR1C2–8 . . . . . . . . . . . . . . . . . . .
Upper End 1C2–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lower End 1C2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR1C2–12 . . . . . . . . . . . . .
ON–VEHICLE SERVICE 1C2–12. . . . . . . . . . . . . . . . . . .
Camshaft Cover 1C2–12. . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Gasket 1C2–13. . . . . . . . . . . . . . . .
Camshafts 1C2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Belt Check and Adjust 1C2–24. . . . . . . . . . . . .
Timing Belt 1C2–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pan 1C2–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pump 1C2–33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Mount 1C2–37. . . . . . . . . . . . . . . . . . . . . . . . . . .
Intake Manifold 1C2–38. . . . . . . . . . . . . . . . . . . . . . . . . . Exhaust Manifold 1C2–41. . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Gears 1C2–43. . . . . . . . . . . . . . . . . . . . . . . . .
Rear Timing Belt Cover 1C2–44. . . . . . . . . . . . . . . . . . .
Engine 1C2–46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pistions and Rods 1C2–51. . . . . . . . . . . . . . . . . . . . . . .
UNIT REPAIR 1C2–56. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Valve Train Components 1C2–56.
Crankshaft 1C2–63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft Bearing and Connecting Rod
Beadings – Gauging Plastics 1C2–72. . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION1C2–75 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Gasket 1C2–75. . . . . . . . . . . . . . . .
Crankshaft 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Timing Belt 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pump 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pan 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold 1C2–75. . . . . . . . . . . . . . . . . . . . . . . .
Intake Manifold 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft 1C2–75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.8L DOHC ENGINE MECHANICAL 1C2 – 7
DAEWOO V–121 BL4
KM–635
Crankshaft Rear
Oil Seal Installer
KM–427
Piston Pin
Service Set
J–8087
Cylinder Bore
Check Gauge
KM–340–0
Cutter Set
Includes: KM–340–7
Guide Drift
KM–340–13
Cutters
KM–340–26
Cutters
KM–470–B
Angular Torque Gauge
KM–498–B
Pressure Gauge
J–8037
Universal Piston
Ring Compressor

1.8L DOHC ENGINE MECHANICAL 1C2 – 51
DAEWOO V–121 BL4
43. Connect the lower radiator hose to the coolant pipe.
44. Connect the upper radiator hose to the thermostat
housing.
45. Connect the heater inlet hose to the cylinder head.
46. Connect the heater outlet hose to the coolant pipe.
47. Connect the coolant surge tank hose to the coolant
pipe.
48. Connect the coolant hose to the throttle body.
49. Connect the throttle cable to the throttle body and
the intake manifold bracket.
50. Install the fuel pump fuse.
51. Connect the negative battery cable.
52. Refill the engine crankcase with engine oil.
53. Refill the engine coolant system. Refer to Section
1D, Engine Cooling.
54. Bleed the power steering system. Refer to Section
6A, Power Steering.
55. Refill the A/C refrigerant system, if equipped. Refer
to Section 7B, Manual Control Heating, Ventilation,
and Air Conditioning System.
56. Install the hood. Refer to Section 9R, Body Front
End.
PISTONS AND RODS
Tools Required
J–8037 Universal Piston Ring Compressor
J–8087 Cylinder Bore Check Gauge
KM–427 Piston Pin Service Set
KM–470–B Angular Torque Gauge
Removal Procedure
1. Remove the cylinder head with the intake manifold
and exhaust manifold attached. Refer to ”Cylinder
Head and Gasket” in this section.
2. Remove the oil pan. Refer to ”Oil Pan” in this sec-
tion.
3. Remove the oil suction pipe bolts and support
bracket bolts.
4. Remove the oil suction pipe.
5. Remove the crankshaft bearing bridge and the oil
pan scraper bolts.
6. Remove the crankshaft bearing bridge and the oil
pan scraper.

1.8L DOHC ENGINE MECHANICAL 1C2 – 53
DAEWOO V–121 BL4
8. Inspect the piston for fit to the connecting rod.
9. Inspect the engine block deck surface for flatness
using a straight edge and a feeler gauge. Refer to
”Engine Specifications” in this section.
10. Inspect the bearing bore for concentricity and align-
ment using cylinder bore check gauge J–8087. Re-
fer to ”Engine Specifications” in this section. If the
bearing bore is beyond specifications, replace the
engine block.
11. Inspect the engine block cylinder bore for wear,
runout, ridging and taper using a bore gauge. Refer
to ”Engine Specifications” in this section.
12. Inspect the engine block cylinder bore for glazing.
Lightly hone the cylinder bore as necessary.
Installation Procedure
Important : For ease of installation of the piston pin, the
connecting rod should be heated to 2805C. Heat the upper
connecting rod only. Use commercial thermocolor materi-
al to determine the correct temperature. When the thermo-
color material changes from black to green, the tempera-
ture is correct for installation.
1. Align the notch on the piston and connecting rod so
that the proper sides will be facing the front of the
engine.
2. Install the piston pin guide through the piston and
the connecting rod.
3. Coat the piston pin with clean oil.
4. Install the piston pin into the opposite side of the
piston.
5. Install the piston pin into the piston and connecting
rod assembly using the piston pin service set
KM–427.
6. Select a set of new piston rings.
7. Measure the piston ring gap using a feeler gauge.
Refer to ”Engine Specifications” in this section.
8. Increase the piston ring gap by carefully filing off
excess material if the piston ring gap is below spec-
ifications.

1D – 8IENGINE COOLING
DAEWOO V–121 BL4
MAINTENANCE AND REPAIR
ON–VEHICLE SERVICE
DRAINING AND REFILLING THE
COOLING SYSTEM
CAUTION : Do not remove the surge tank cap while
the engine and the radiator are hot. Scalding fluid and
steam may be blown out under pressure.
1. Place a pan below the vehicle to catch the draining
coolant.
2. Remove the surge tank cap.
3. Unplug the drain cock.
CAUTION : Dispose of the used coolant to a used
coolant holding tank to be picked up with the used oil
for disposal. Never pour the used coolant down the
drain. Ethylene glycol antifreeze is an extremely toxic
chemical. Disposing of it into the sewer system or the
ground water can contaminate the local environment.
4. Catch the escaping fluid in a drain pan.
5. Remove all sludge and dirt from inside the surge
tank. Refer to ”Surge Tank” in this section.
6. Plug the drain cock.
7. Add the clean water to the surge tank.
8. Fill the tank slowly so that the upper reservoir hose
remains above the water line. This allows the air
inside the cooling system to escape.
9. Start the engine.
10. Run the engine until the thermostat opens. You can
tell the thermostat is open when both radiator
hoses are hot to the touch.
11. Stop the engine.
12. Repeat Steps 1 through 9 until the drained water is
clear and free of coolant and rust.
Notice : Never use an antifreeze mixture more concen-
trated than 60 percent antifreeze to 40 percent water. The
solution freezing point increases above this concentration.
13. Fill the cooling system through the surge tank with
a mixture of ethylene glycol antifreeze and water.
The mixture must be at least 50 percent antifreeze,
but not more than 60 percent antifreeze.
14. Fill the surge tank to the specified MAX fill mark on
the outside of the tank.

1E – 32IENGINE ELECTRICAL
DAEWOO V–121 BL4
the same cable to the positive terminal on the other
battery. Never connect the other end to the nega-
tive terminal of the discharged battery.
CAUTION : To avoid injury do not attach the cable di-
rectly to the negative terminal of the discharged bat-
tery. Doing so could cause sparks and a possible bat-
tery explosion.
6. Clamp one end of the second cable to the negative
terminal of the booster battery. Make the final con-
nection to a solid engine ground (such as the en-
gine lift bracket) at least 450 millimeters (18 inches)
from the discharged battery.
7. Start the engine of the vehicle with the good bat-
tery. Run the engine at a moderate speed for sever-
al minutes. Then start the engine of the vehicle
which has the discharged battery.
8. Remove the jumper cables by reversing the above
sequence exactly. Remove the negative cable from
the vehicle with the discharged battery first. While
removing each clamp, take care that it does not
touch any other metal while the other end remains
attached.
GENERATOR
The Delco–Remy CS charging system has several mod-
els available, including the CS. The number denotes the
outer diameter in millimeters of the stator lamination.
CS generators are equipped with internal regulators. A
Delta stator, a rectifier bridge, and a rotor with slip rings
and brushes are electrically similar to earlier generators.
A conventional pulley and fan are used. There is no test
hole.
Unlike three–wire generators, the CS may be used with
only two connections: battery positive and an ”L’’ terminal
to the charge indicator lamp.
As with other charging systems, the charge indicator lamp
lights when the ignition switch is turned to RUN, and goes
out when the engine is running. If the charge indicator is
on with the engine running, a charging system defect is in-
dicated. This indicator light will glow at full brilliance for
several kinds of defects as well as when the system volt-
age is too high or too low.The regulator voltage setting varies with temperature and
limits the system voltage by controlling rotor field current.
At high speeds, the on–time may be 10 percent and the
off–time 90 percent. At low speeds, with high electrical
loads, on–time may be 90 percent and the off–time 10 per-
cent.
CHARGING SYSTEM
CS generators use a new type of regulator that incorpo-
rates a diode trio. A Delta stator, a rectifier bridge, and a
rotor with slip rings and brushes are electrically similar to
earlier generators. A conventional pulley and fan are used.
There is no test hole.
STARTER
Wound field starter motors have pole pieces, arranged
around the armature, which are energized by wound field
coils.
Enclosed shift lever cranking motors have the shift lever
mechanism and the solenoid plunger enclosed in the drive
housing, protecting them from exposure to dirt, icy condi-
tions, and splashes.
In the basic circuit, solenoid windings are energized when
the switch is closed. The resulting plunger and shift lever
movement causes the pinion to engage the engine fly-
wheel ring gear. The solenoid main contacts close. Crank-
ing then takes place.
When the engine starts, pinion overrun protects the arma-
ture from excessive speed until the switch is opened, at
which time the return spring causes the pinion to disen-
gage. To prevent excessive overrun, the switch should be
released immediately after the engine starts.
STARTING SYSTEM
The engine electrical system includes the battery, the igni-
tion, the starter, the generator, and all the related wiring.
Diagnostic tables will aid in troubleshooting system faults.
When a fault is traced to a particular component, refer to
that component section of the service manual.
The starting system circuit consists of the battery, the
starter motor, the ignition switch, and all the related electri-
cal wiring. All of these components are connected electri-
cally.

ENGINE CONTROLS 1F – 5
DAEWOO V–121 BL4
SYMPTOM DIAGNOSIS1F–574 . . . . . . . . . . . . . . . . . . .
Important Preliminary Checks 1F–574. . . . . . . . . . . . .
Intermittents 1F–574. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hard Start 1F–576. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surges or Chuggles 1F–579. . . . . . . . . . . . . . . . . . . . . .
Lack of Power, Sluggishness, or Sponginess 1F–581
Hesitation, Sag, Stumble 1F–583. . . . . . . . . . . . . . . . .
Cuts Out, Misses 1F–584. . . . . . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy 1F–587. . . . . . . . . . . . . . . . . . . . . .
Rough, Unstable, or Incorrect Idle, Stalling 1F–588. .
Excessive Exhaust Emissions or Odors 1F–591. . . . .
Dieseling, Run–On 1F–592. . . . . . . . . . . . . . . . . . . . . . .
Backfire 1F–593. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE AND REPAIR1F–594 . . . . . . . . . . . . .
ON–VEHICLE SERVICE 1F–594. . . . . . . . . . . . . . . . . . .
Fuel System Pressure Relief 1F–594. . . . . . . . . . . . . .
Fuel Tank 1F–594. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump 1F–596. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Filter 1F–597. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Rail and Injectors (1.4L/1.6L DOHC) 1F–598. . .
Fuel Rail and Injectors (1.8L DOHC) 1F–600. . . . . . .
Engine Coolant Temperature Sensor
(1.4L/1.6L DOHC) 1F–602. . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor
(1.8L DOHC) 1F–602. . . . . . . . . . . . . . . . . . . . . . . . . .
Throttle Position Sensor (1.8L DOHC) 1F–603. . . . . .
Throttle Body (1.4L/1.6L DOHC) 1F–603. . . . . . . . . . .
Throttle Body (1.8L DOHC) 1F–604. . . . . . . . . . . . . . .
Front Heated Oxygen Sensor (HO2S 1)
(1.4L/1.6L DOHC) 1F–606. . . . . . . . . . . . . . . . . . . . . .
Front Heated Oxygen Sensor (HO2S 1)
(1.8L DOHC) 1F–607. . . . . . . . . . . . . . . . . . . . . . . . . .
Rear Heated Oxygen Sensor (HO2S 2) 1F–607. . . . .
Intake Air Temperature Sensor
(1.4L/1.6L DOHC) 1F–608. . . . . . . . . . . . . . . . . . . . . .
Intake Air Temperature Sensor (1.8L DOHC) 1F–609
Idle Air Control Valve (1.8L DOHC) 1F–609. . . . . . . . .
Manifold Absolute Pressure Sensor
(1.4L/1.6L DOHC) 1F–610. . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Sensor
(1.8L DOHC) 1F–611. . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Gas Recirculation Valve
(1.4L/1.6L DOHC) 1F–611. . . . . . . . . . . . . . . . . . . . . .
Exhaust Gas Recirculation Valve (1.8L DOHC) 1F–612
Knock Sensor (1.4L/1.6L DOHC) 1F–612. . . . . . . . . .
Knock Sensor (1.8L DOHC) 1F–613. . . . . . . . . . . . . . .
Evaporative Emission Canister 1F–614. . . . . . . . . . . . Evaporative Emission Canister Purge Solenoid Valve 1
F–615
Crankshaft Position (CKP) Sensor
(1.4L/1.6L DOHC) 1F–615. . . . . . . . . . . . . . . . . . . . . .
Crankshaft Position (CKP) Sensor
(1.8L DOHC) 1F–616. . . . . . . . . . . . . . . . . . . . . . . . . .
Camshaft Position Sensor (1.4L/1.6L DOHC) 1F–618
Camshaft Position Sensor (1.8L DOHC) 1F–619. . . .
Engine Control Module (1.4L/1.6L DOHC) 1F–620. . .
Engine Control Module (1.8L DOHC) 1F–621. . . . . . .
Electronic Ignition System Ignition Coil
(1.4L/1.6L DOHC) 1F–621. . . . . . . . . . . . . . . . . . . . . .
Electronic Ignition System Ignition Coil
(1.8L DOHC) 1F–622. . . . . . . . . . . . . . . . . . . . . . . . . .
GENERAL DESCRIPTION AND SYSTEM
OPERATION1F–623 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ignition System Operation 1F–623. . . . . . . . . . . . . . . .
Electronic Ignition System Ignition Coil 1F–623. . . . . .
Crankshaft Position Sensor 1F–623. . . . . . . . . . . . . . .
Camshaft Position Sensor 1F–623. . . . . . . . . . . . . . . .
Idle Air System Operation 1F–623. . . . . . . . . . . . . . . . .
Fuel Control System Operation 1F–623. . . . . . . . . . . .
Evaporative Emission Control System
Operation 1F–624. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Evaporative Emission Canister 1F–625. . . . . . . . . . . .
Positive Crankcase Ventilation System
Operation 1F–625. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 1F–625. . . . . . .
Throttle Position Sensor 1F–625. . . . . . . . . . . . . . . . . .
Catalyst Monitor Oxygen Sensors 1F–625. . . . . . . . . .
Exhaust Gas Recirculation Valve 1F–626. . . . . . . . . . .
Intake Air Temperature Sensor 1F–626. . . . . . . . . . . .
Idle Air Control Valve 1F–626. . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Sensor 1F–626. . . . . . . .
Engine Control Module 1F–627. . . . . . . . . . . . . . . . . . .
Fuel Injector 1F–627. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knock Sensor 1F–627. . . . . . . . . . . . . . . . . . . . . . . . . . .
Rough Road Sensor 1F–627. . . . . . . . . . . . . . . . . . . . .
Strategy–Based Diagnostics 1F–628. . . . . . . . . . . . . .
EOBD Serviceability Issues 1F–628. . . . . . . . . . . . . . .
Serial Data Communications 1F–629. . . . . . . . . . . . . .
On–Board Diagnostic (EOBD) 1F–629. . . . . . . . . . . . .
Comprehensive Component Monitor Diagnostic
Operation 1F–630. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common EOBD Terms 1F–630. . . . . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes 1F–632. . . . . . . . .
Primary System–Based Diagnostics 1F–633. . . . . . . .

ENGINE CONTROLS 1F – 601
DAEWOO V–121 BL4
Notice : Before removal, the fuel rail assembly may be
cleaned with a spray–type cleaner, following package in-
structions. Do not immerse the fuel rails in liquid cleaning
solvent. Use care in removing the fuel rail assembly to pre-
vent damage to the electrical connectors and the injector
spray tips. Prevent dirt and other contaminants from enter-
ing open lines and passages. Fittings should be capped
and holes plugged during service.
Important : If an injector becomes separated from the rail
and remains in the cylinder head, replace the injector O–
ring seals and the retaining clip.
9. Remove the fuel rail with the injectors attached.
10. Remove the fuel injector retainer clips.
11. Remove the fuel injectors by pulling them down and
out.
12. Discard the fuel injector O–rings.
Installation Procedure
Important : Different injectors are calibrated for different
flow rates. When ordering new fuel injectors, be certain to
order the identical part number that is inscribed on the old
injector.
1. Lubricate the new fuel injector O–rings with engine
oil. Install the new O–rings on the fuel injectors.
2. Install the fuel injectors into the fuel rail sockets
with the fuel injector terminals facing outward.
3. Install the fuel injector retaining clips onto the fuel
injector and the fuel rail ledge.
4. Make sure that the clips are parallel to the fuel in-
jector harness connector.
5. Install the fuel rail assembly into the cylinder head.
6. Install the fuel rail retaining bolts.
Tighten
Tighten the fuel rail retaining bolts to 25 NSm (18 lb–
ft).
7. Connect the fuel feed line to the fuel rail.
8. Connect the fuel injector connectors. Rotate each
fuel injector as required.

ENGINE CONTROLS 1F – 623
DAEWOO V–121 BL4
GENERAL DESCRIPTION
AND SYSTEM OPERATION
IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distribu-
tor and coil. It uses a crankshaft position sensor input to
the engine control module (ECM). The ECM then deter-
mines Electronic Spark Timing (EST) and triggers the di-
rect ignition system ignition coil.
This type of distributorless ignition system uses a ”waste
spark” method of spark distribution. Each cylinder is
paired with the cylinder that is opposite it (1–4 or 2–3). The
spark occurs simultaneously in the cylinder coming up on
the compression stroke and in the cylinder coming up on
the exhaust stroke. The cylinder on the exhaust stroke re-
quires very little of the available energy to fire the spark
plug. The remaining energy is available to the spark plug
in the cylinder on the compression stroke.
These systems use the EST signal from the ECM to con-
trol the electronic spark timing. The ECM uses the follow-
ing information:
S Engine load (manifold pressure or vacuum).
S Atmospheric (barometric) pressure.
S Engine temperature.
S Intake air temperature.
S Crankshaft position.
S Engine speed (rpm).
ELECTRONIC IGNITION SYSTEM
IGNITION COIL
The Electronic Ignition (EI) system ignition coil provides
the spark for two spark plugs simultaneously. The EI sys-
tem ignition coil is not serviceable and must be replaced
as an assembly.
CRANKSHAFT POSITION SENSOR
This direct ignition system uses a magnetic crankshaft
position sensor. This sensor protrudes through its mount
to within approximately 0.05 inch (1.3 mm) of the crank-
shaft reluctor. The reluctor is a special wheel attached to
the crankshaft or crankshaft pulley with 58 slots machined
into it, 57 of which are equally spaced in 6 degree intervals.
The last slot is wider and serves to generate a ”sync
pulse.” As the crankshaft rotates, the slots in the reluctor
change the magnetic field of the sensor, creating an in-
duced voltage pulse. The longer pulse of the 58th slot
identifies a specific orientation of the crankshaft and al-
lows the engine control module (ECM) to determine the
crankshaft orientation at all times. The ECM uses this in-
formation to generate timed ignition and injection pulses
that it sends to the ignition coils and to the fuel injectors.
CAMAHAFT POSITION SENSOR
The Camshaft Position (CMP) sensor sends a CMP sen-
sor signal to the engine control module (ECM). The ECM
uses this signal as a ”sync pulse” to trigger the injectors in
the proper sequence. The ECM uses the CMP sensor sig-
nal to indicate the position of the #1 piston during its power
stroke. This allows the ECM to calculate true sequential
fuel injection mode of operation. If the ECM detects an in-
correct CMP sensor signal while the engine is running,
DTC P0341 will set. If the CMP sensor signal is lost while
the engine is running, the fuel injection system will shift to
a calculated sequential fuel injection mode based on the
last fuel injection pulse, and the engine will continue to run.
As long as the fault is present, the engine can be restarted.
It will run in the calculated sequential mode with a 1–in–6
chance of the injector sequence being correct.
IDLE AIR SYSTEM OPERATION
The idle air system operation is controlled by the base idle
setting of the throttle body and the Idle Air Control (IAC)
valve.
The engine control module (ECM) uses the IAC valve to
set the idle speed dependent on conditions. The ECM
uses information from various inputs, such as coolant tem-
perature, manifold vacuum, etc., for the effective control
of the idle speed.
FUEL CONTROL SYSTEM
OPERATION
The function of the fuel metering system is to deliver the
correct amount of fuel to the engine under all operating
conditions. The fuel is delivered to the engine by the indi-
vidual fuel injectors mounted into the intake manifold near
each cylinder.
The two main fuel control sensors are the Manifold Abso-
lute Pressure (MAP) sensor, the Front Heated Oxygen
Sensor (HO2S1) and the Rear Heated Oxygen Sensor
(HO2S2).
The MAP sensor measures or senses the intake manifold
vacuum. Under high fuel demands the MAP sensor reads
a low vacuum condition, such as wide open throttle. The
engine control module (ECM) uses this information to ri-
chen the mixture, thus increasing the fuel injector on–time,
to provide the correct amount of fuel. When decelerating,
the vacuum increases. This vacuum change is sensed by
the MAP sensor and read by the ECM, which then de-
creases the fuel injector on–time due to the low fuel de-
mand conditions.
HO2S Sensors
The HO2S sensor is located in the exhaust manifold. The
HO2S sensor indicates to the ECM the amount of oxygen
in the exhaust gas and the ECM changes the air/fuel ratio
to the engine by controlling the fuel injectors. The best air/
fuel ratio to minimize exhaust emissions is 14.7 to 1, which
allows the catalytic converter to operate most efficiently.