2003 DAEWOO MATIZ oil pressure

DAEWOO M-150 BL2
SECTION 1B
SOHC 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 B unless otherwise
noted.
TABLE OF CONTENTS
Description and Operation 1B-2. . . . . . . . . . . . . . . . . .
Engine Type 1B-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Lubrication 1B-2. . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Valve Train 1B-2. . . . . . . . . . . . . .
Engine Block 1B-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Crankshaft 1B-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connecting Rod 1B-3. . . . . . . . . . . . . . . . . . . . . . . . . . .
Piston, Piston Ring and Piston Pin 1B-3. . . . . . . . . . .
Timing Belt and Pulley 1B-4. . . . . . . . . . . . . . . . . . . . .
Engine Mount 1B-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component Locator 1B-5. . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head 1B-5. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Block 1B-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manifold & Air Flow System 1B-7. . . . . . . . . . . . . . . . .
Timing Belt & Engine Mount 1B-8. . . . . . . . . . . . . . . .
Diagnostic Information and Procedure 1B-9. . . . . . .
Compression Pressure Check 1B-9. . . . . . . . . . . . . . .
Oil Pressure Check 1B-9. . . . . . . . . . . . . . . . . . . . . . . .
Adjustment of Valve Clearance 1B-10. . . . . . . . . . . . .
Ignition Timing Check and Adjustment
(Typical) 1B-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Valve Timing Check and Adjustment 1B-12. . . . . . . .
Repair Instructions 1B-14. . . . . . . . . . . . . . . . . . . . . . . .
On-Vehicle Service 1B-14. . . . . . . . . . . . . . . . . . . . . . . . . Air Filter Assembly 1B-14. . . . . . . . . . . . . . . . . . . . . . .
Air Filter Element 1B-15. . . . . . . . . . . . . . . . . . . . . . . . .
Positive Crankcase Ventilation (PCV) Hose
and Valve 1B-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Intake Manifold 1B-16. . . . . . . . . . . . . . . . . . . . . . . . . . .
Exhaust Manifold (Typical) 1B-18. . . . . . . . . . . . . . . . .
Exhaust Manifold (Euro III) 1B-20. . . . . . . . . . . . . . . .
Timing Belt 1B-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pan 1B-23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Oil Pump 1B-24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Distributor Case 1B-26. . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Gasket 1B-28. . . . . . . . . . . . . . . . .
Engine Mount Damping Block 1B-32. . . . . . . . . . . . . .
Engine Mount Front Damping Bush 1B-34. . . . . . . . .
Engine Assembly 1B-35. . . . . . . . . . . . . . . . . . . . . . . . .
Unit Repair 1B-47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cylinder Head and Valve Train
Components 1B-47. . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Block Components 1B-59. . . . . . . . . . . . . . . . .
Specifications 1B-71. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Specifications 1B-71. . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specifications 1B-73. . . . . . . . . .
Special Tools 1B-75. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1B-75. . . . . . . . . . . . . . . . . . . . . . .

SOHC ENGINE MECANICAL 1B–3
DAEWOO M-150 BL2
parts are installed in the cross flow arrangement. The
rocker arm (i) operates in seesaw motion to close and
open the intake and exhaust valves (j) with camshaft by
turning the rocker arm shaft of each intake and exhaust
part.
ENGINE BLOCK
As the largest part of the engine components. the block
(l) has all the necessary parts attached to outer surface
of it.
On the inside surface of block, there are bore surfaces
by horning, which are cylinders, and on the periphery of
the cylinders, there are the passages to prevent the
over-heated and to lubricate the engine block.
CRANKSHAFT
The crankshaft (m) is to convert the rectilinear motion
into the rotation motion through the connecting rod (n)
which transmits the power generated by combustion.
On the one side of it, oil pump, crankshaft pulley and
timing belt pulley are attached, and oil seal housing and
flywheel are on the other side.
A special steel of high grade cast iron is used for the ma-
terial to stand the bending load and distortion. The mate-
rial of the main bearing (o) is aluminum alloy. The split
thrust bearings (p) are inserted in the journal bearing
part (No.3).
D102B004
CONNECTING ROD
The connecting rods (n) are made of forged steel, and
its section is typed “I” with its big end connected tocrankshaft (m) and its small end to piston pin to transmit
the power.
The big end is detachable, and its upper and lower parts
are fastened by bolting after the metal bearings (q) are
inserted.
PISTON, PISTON RING AND PISTON
PIN
Piston
The piston (r) is of the open skirt type and its crown is
exposed in the combustion chamber to generate power.
Its land and skirt parts are made of coat aluminum alloy
which is light and has excellent heat conductivity in order
to meet its continuous and high speed reciprocation
movement.
Piston Ring
It is composed of two compression rings (s) and one oil
ring (t) and installed between the grooves of the piston
to make the high speed reciprocating movement main-
taining a remarkable air tightness as well as cylinders. It
is a critical parts to affect the compression pressure, oil
consumption, compression, blow by pressure and en-
gine performance.
Piston Pin
The pin (u) is not fixed to the piston or connecting rod
and its both ends are assembled by the circlip (v) in the
full floating type. The pin is used to transmit the power
from the crown part of piston to connecting rod.
D102B005

SOHC ENGINE MECANICAL 1B–9
DAEWOO M-150 BL2
DIAGNOSTIC INFORMATION AND PROCEDURE
COMPRESSION PRESSURE CHECK
Tools Required
09915–64510 Compression Pressure Gauge
Check the compression pressure in the following proce-
dures:
1. Warm up the engine to the normal operating tempera-
ture (Cooling temperature : 80–90C (176–194F)).
2. Stop the engine and then remove the high tension
cable and the spark plug.
3. Disconnect the distributor optical sensor connector.
4. Install the compression pressure gauge 09915–64510
(a) in the hole of spark plug.
D12B301A
5. Disengage the clutch in Neutral (to lighten starting
load on engine upon cranking), and depress the ac-
celerator all the way to make the throttle fully open.
6. Crank the engine with the starting motor, and read the
highest pressure on the compression pressure gauge.
The difference of measured value between cylinders
is 98.06kPa (14.22 psi) and less.
On checking, make the connection perfectly airtight
between the hole of spark plug and compression pres-
sure gauge.
Unit Standard Limit



Compression
Pressure
– 400 rpm
kPa(psi)1,225.75
(177.73)
1,176.72–
1,274.78
(170.62–
184.84)
7. After checking, remove the gauge and install the re-
moved parts.
OIL PRESSURE CHECK
Tools Required
09915–77310 Oil Pressure Gauge
Prior to check oil pressure, check the followings:
Check oil level and add if required.
Replace the discolored, deteriorated or diluted oil.
Check any oil leakage and repair the defective parts.
Check the compression pressure in the following proce-
dures:
1. Remove the oil pressure switch (b) from the cylinder
block.
2. Install the oil pressure gauge 09915–77310 (c) to the
mounting place of the oil pressure switch.
D12B302A
3. Start the engine and warm up to the normal operating
temperature.
4. Raise the engine speed up to 2,000rpm and then
read oil pressure.
Item Unit Standard
Oil Pressure – 2000rpmkPa
(psi)245.15–294.18
(35.55–42.66)
5. After checking, wrap the threads of oil pressure
switch with a seal tape and tighten it to the specified
torque 12–16 N
m (106–144 lb-in).
6. Start the engine and check oil pressure switch for oil
leakage.

ENGINE COOLING 1D–9
DAEWOO M-150 BL2
REPAIR INSTRUCTIONS
ON–VEHICLE SERVICE
D12D5011
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. Drain the coolant.
Remove the surge tank cap (1).
Disconnect the lower radiator hose (2).
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 sys-
tem or the ground water can contaminate the local
environment.
D102D502
3. Connect the lower radiator hose.
4. Clean the cooling system.
Remove all sludge and dirt from inside the surge
tank. And install the surge tank. Refer to “Surge
Tank” in this section (1).

DAEWOO M-150 BL2
SECTION 1F
ENGINE CONTROLS
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
Description and Operation 1F-4. . . . . . . . . . . . . . . . . .
Ignition System Operation 1F-4. . . . . . . . . . . . . . . . . .
Electronic Ignition System Ignition Coil 1F-4. . . . . . .
Crankshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . .
Camshaft Position Sensor 1F-4. . . . . . . . . . . . . . . . . .
Idle Air System Operation 1F-4. . . . . . . . . . . . . . . . . .
Fuel Control System Operation 1F-4. . . . . . . . . . . . . .
Evaporative Emission Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Controlled Charcoal Canister 1F-5. . . . . . . . . . . . . . . .
Positive Crankcase Ventilation Control System
Operation 1F-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature Sensor 1F-6. . . . . . . . .
Throttle Position Sensor 1F-6. . . . . . . . . . . . . . . . . . . .
Catalyst Monitor Oxygen Sensors 1F-6. . . . . . . . . . .
Electric Exhaust Gas Recirculation Valve 1F-6. . . . .
Intake Air Temperature Sensor 1F-7. . . . . . . . . . . . . .
Idle Air Control Valve 1F-7. . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Sensor 1F-7. . . . . . . . . .
Engine Control Module 1F-8. . . . . . . . . . . . . . . . . . . . .
Fuel Injector 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Cutoff Switch (Inertia Switch) 1F-8. . . . . . . . . . .
Knock Sensor 1F-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Variable Reluctance (VR) Sensor 1F-8. . . . . . . . . . . .
Octane Number Connector 1F-8. . . . . . . . . . . . . . . . .
Strategy-Based Diagnostics 1F-9. . . . . . . . . . . . . . . .
EOBD Serviceability Issues 1F-9. . . . . . . . . . . . . . . . .
Serial Data Communications 1F-10. . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) 1F-10. . . . . . . . .
Comprehensive Component Monitor Diagnostic
Operation 1F-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Common EOBD Terms 1F-11. . . . . . . . . . . . . . . . . . . .
DTC Types 1F-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reading Diagnostic Trouble Codes 1F-13. . . . . . . . .
Primary System-Based Diagnostics 1F-15. . . . . . . . Diagnostic Information and Procedures 1F-17. . . .
System Diagnosis 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Diagnostic Aids 1F-17. . . . . . . . . . . . . . . . . . . . . . . . . .
Idle Learn Procedure 1F-17. . . . . . . . . . . . . . . . . . . . .
Euro On-Board Diagnostic (EOBD) System
Check 1F-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ECM Output Diagnosis 1F-20. . . . . . . . . . . . . . . . . . . .
Multiple ECM Information Sensor DTCs Set 1F-21. .
Engine Cranks But Will Not Run 1F-25. . . . . . . . . . . .
No Malfunction Indicator Lamp 1F-30. . . . . . . . . . . . .
Malfunction Indicator Lamp On Steady 1F-32. . . . . .
Fuel System Diagnosis 1F-34. . . . . . . . . . . . . . . . . . . .
Fuel Pump Relay Circuit Check 1F-36. . . . . . . . . . . .
Main Relay Circuit Check 1F-38. . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure Check 1F-40. . . . . . . . . .
Idle Air Control System Check 1F-42. . . . . . . . . . . . .
Ignition System Check 1F-45. . . . . . . . . . . . . . . . . . . .
Engine Cooling Fan Circuit Check 1F-48. . . . . . . . . .
Data Link Connector Diagnosis 1F-52. . . . . . . . . . . . .
Fuel Injector Balance Test 1F-54. . . . . . . . . . . . . . . . .
Diagnostic Trouble Code Diagnosis 1F-55. . . . . . . .
Clearing Trouble Codes 1F-55. . . . . . . . . . . . . . . . . . .
Diagnostic Trouble Codes 1F-55. . . . . . . . . . . . . . . . .
DTC P0107 Manifold Absolute Pressure Sensor
Low Voltage 1F-58. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0108 Manifold Pressure Sensor High
Voltage 1F-62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0112 Intake Air Temperature Sensor Low
Voltage 1F-66. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0113 Intake Air Temperature Sensor High
Voltage 1F-68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0117 Engine Coolant Temperature Sensor
Low Voltage 1F-72. . . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P0118 Engine Coolant Temperature Sensor
High Voltage 1F-74. . . . . . . . . . . . . . . . . . . . . . . . . . .

ENGINE CONTROLS 1F–3
DAEWOO M-150 BL2
DTC P1628 Immobilizer No Successful
Communication 1F-270. . . . . . . . . . . . . . . . . . . . . . .
DTC P1629 Immovilizer Wrong Computation 1F-272
DTC P0656 Fuel Level Gauge Circuit Fault 1F-274.
DTC P1660 Malfunction Indicator Lamp (MIL)
High Voltage 1F-276. . . . . . . . . . . . . . . . . . . . . . . . . .
DTC P1661 Malfunction Indicator Lamp (MIL)
Low Voltage 1F-278. . . . . . . . . . . . . . . . . . . . . . . . . .
Symptom Diagnosis 1F-280. . . . . . . . . . . . . . . . . . . . . .
Important Preliminary Checks 1F-280. . . . . . . . . . . . .
Intermittent 1F-281. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Hard Start 1F-283. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Surges or Chuggles 1F-286. . . . . . . . . . . . . . . . . . . . .
Lack of Power, Sluggishness or Sponginess 1F-288
Detonation/Spark Knock 1F-290. . . . . . . . . . . . . . . . . .
Hesitation, Sag, Stumble 1F-292. . . . . . . . . . . . . . . . .
Cuts Out, Misses 1F-294. . . . . . . . . . . . . . . . . . . . . . . .
Poor Fuel Economy 1F-296. . . . . . . . . . . . . . . . . . . . . .
Rough, Unstable, or Incorrect Idle, Stalling 1F-297. .
Excessive Exhaust Emissions or Odors 1F-300. . . .
Dieseling, Run-on 1F-302. . . . . . . . . . . . . . . . . . . . . . .
Backfire 1F-303. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Maintenance and Repair 1F-304. . . . . . . . . . . . . . . . . .
On-Vehicle Service 1F–304 . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump 1F–304 . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pressure Regulator 1F-305. . . . . . . . . . . . . . . . .
Fuel Filter 1F-306. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Tank 1F-307. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Rail and Injectors 1F-308. . . . . . . . . . . . . . . . . . .
Evaporator Emission Canister 1F-309. . . . . . . . . . . . . Evaporator Emission Canister Purge
Solenoid 1F-310. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Manifold Absolute Pressure (MAP) Sensor 1F-310. .
Throttle Body 1F-311. . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine Coolant Temperature (ECT) Sensor 1F-312.
Intake Air Temperature (ECT) Sensor 1F-313. . . . . .
Oxygen Sensor (O2S 1) 1F-314. . . . . . . . . . . . . . . . . .
Heated Oxygen Sensor (HO2S 2) 1F-314. . . . . . . . .
Electric Exhaust Gas Recirculation (EEGR)
Valve 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Knock Sensor 1F-315. . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic Ignition (EI) System Ignition Coil 1F-316.
Crankshaft Position (CKP) Sensor 1F-316. . . . . . . .
Camshaft Position (CMP) Sensor 1F-317. . . . . . . . . .
Engine Control Module (ECM) 1F-317. . . . . . . . . . . . .
Specifications 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fastener Tightening Specification 1F-319. . . . . . . . . .
Special Tools 1F-319. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special Tools Table 1F-319. . . . . . . . . . . . . . . . . . . . . .
Schematic and Routing Diagrams 1F-320. . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 1 of 5) 1F-320. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 2 of 5) 1F-321. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 3 of 5) 1F-322. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 4 of 5) 1F-323. . . . . . . . . . . . . . . . . . . .
ECM Wiring Diagram
(Sirius D3 – 5 of 5) 1F-324. . . . . . . . . . . . . . . . . . . .

1F–4 ENGINE CONTROLS
DAEWOO M-150 BL2
DESCRIPTION AND OPERATION
IGNITION SYSTEM OPERATION
This ignition system does not use a conventional distrib-
utor and coil. It uses a crankshaft position sensor input
to the Engine Control Module (ECM). The ECM then de-
termines Electronic Spark Timing (EST) and triggers the
electronic ignition system ignition coil.
This type of distributorless ignition system uses a “waste
spark’’ method of spark distribution. Each cylinder is in-
dividural with coil per cylinder.
These systems use the EST signal from the ECM to
control the EST. The ECM uses the following informa-
tion:

Engine load (manifold pressure or vacuum).

Atmospheric (barometric) pressure.

Engine temperature.

Intake air temperature.

Crankshaft position.

Engine speed (rpm).
ELECTRONIC IGNITION SYSTEM
IGNITION COIL
The Electronic Ignition (EI) system ignition coil is
mounted near on the cylinder head.
A terminals of the EI system ignition coil provides the
spark for each spark plug. The EI system ignition coil is
not serviceable and must be replaced as an assembly.
CRANKSHAFT POSITION SENSOR
This Electronic Ignition (EI) system uses a magnetic
crankshaft position sensor. This sensor protrudes
through its mount to within approximately 1.3 mm (0.05
inch) of the crankshaft reluctor. The reluctor is a special
wheel attached to the crankshaft with 58 slots machined
into it, 57 of which are equally spaced in 6-degree inter-
vals. 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, creat-
ing an induced voltage pulse. The longer pulse of the
58th slot identifies a specific orientation of the crank-
shaft and allows the Engine Control Module (ECM) to
determine the crankshaft orientation at all times. The
ECM uses this information to generate timed ignition
and injection pulses that it sends to the ignition coils and
to the fuel injectors.
CAMSHAFT POSITION SENSOR
The Camshaft Position (CMP) sensor sends a CMP sig-
nal 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 signal to indi-
cate the position of the #1 piston during its power stroke.
This allows the ECM to calculate true sequential fuel in-jection mode of operation. If the ECM detects an incor-
rect CMP signal while the engine is running, Diagnostic
Trouble Code (DTC) P0341 will set. If the CMP 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 en-
gine can be restarted. It will run in the calculated se-
quential 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
temperature, 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 in-
dividual fuel injectors mounted into the intake manifold
near each cylinder.
The main fuel control sensors are the Manifold Absolute
Pressure (MAP) sensor, the oxygen sensor (O2S), and
the heated oxygen sensor (HO2S).
The MAP sensor measures or senses the intake man-
ifold 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 in-
formation to enrich 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 decreases the fuel injector on-time
due to the low fuel demand conditions.
The O2S is located in the exhaust manifold. The HO2S
is located in the exhaust pipe. The oxygen sensors indi-
cate to the ECM the amount of oxygen in the exhaust
gas, and the ECM changes the air/fuel ratio to the en-
gine by controlling the fuel injectors. The best air/fuel ra-
tio to minimize exhaust emissions is 14.7:1, which
allows the catalytic converter to operate most efficiently.
Because of the constant measuring and adjusting of the
air/fuel ratio, the fuel injection system is called a “closed
loop” system.
The ECM uses voltage inputs from several sensors to
determine how much fuel to provide to the engine. The

1F–10 ENGINE CONTROLS
DAEWOO M-150 BL2
fuels use alcohol to increase the octane rating of the
fuel. Although alcohol-enhanced fuels may raise the oc-
tane rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.
Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.
Non-OEM Parts
The EOBD system has been calibrated to run with Origi-
nal Equipment Manufacturer (OEM) parts. Something
as simple as a high performance-exhaust system that
affects exhaust system back pressure could potentially
interfere with the operation of the Electric Exhaust Gas
Recirculation (EEGR) valve and thereby turn on the
MIL. Small leaks in the exhaust system near the heated
oxygen sensor (HO2S) can also cause the MIL to turn
on.
Aftermarket electronics, such as cellular phones, ster-
eos, and anti-theft devices, may radiate Electromagnet-
ic Interference (EMI) into the control system if they are
improperly installed. This may cause a false sensor
reading and turn on the MIL.
Environment
Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition sys-
tem. If the ignition system is rain-soaked, it can tempo-
rarily cause engine misfire and turn on the MIL.
Vehicle Marshaling
The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 2 to 3 miles of driving. This type of opera-
tion contributes to the fuel fouling of the spark plugs and
will turn on the MIL with a set DTC P0300.
Poor Vehicle Maintenance
The sensitivity of the EOBD will cause the MIL to turn on
if the vehicle is not maintained properly. Restricted air fil-
ters, fuel filters, and crankcase deposits due to lack of oil
changes or improper oil viscosity can trigger actual ve-
hicle faults that were not previously monitored prior to
EOBD. Poor vehicle maintenance can not be classified
as a “non-vehicle fault,” but with the sensitivity of the
EOBD, vehicle maintenance schedules must be more
closely followed.
Severe Vibration
The Misfire diagnostic measures small changes in the
rotational speed of the crankshaft. Severe driveline
vibrations in the vehicle, such as caused by an exces-
sive amount of mud on the wheels, can have the same
effect on crankshaft speed as misfire and, therefore,
may set DTC P0300.
Related System Faults
Many of the EOBD system diagnostics will not run if the
Engine Control Module (ECM) detects a fault on a re-
lated system or component. One example would be thatif the ECM detected a Misfire fault, the diagnostics on
the catalytic converter would be suspended until the
Misfire fault was repaired. If the Misfire fault is severe
enough, the catalytic converter can be damaged due to
overheating and will never set a Catalyst DTC until the
Misfire fault is repaired and the Catalyst diagnostic is al-
lowed to run to completion. If this happens, the custom-
er may have to make two trips to the dealership in order
to repair the vehicle.
SERIAL DATA COMMUNICATIONS
Keyword 2000 Serial Data
Communications
Government regulations require that all vehicle
manufacturers establish a common communication sys-
tem. This vehicle utilizes the “Keyword 2000” commu-
nication system. Each bit of information can have one of
two lengths: long or short. This allows vehicle wiring to
be reduced by transmitting and receiving multiple sig-
nals over a single wire. The messages carried on Key-
word 2000 data streams are also prioritized. If two
messages attempt to establish communications on the
data line at the same time, only the message with higher
priority will continue. The device with the lower priority
message must wait. The most significant result of this
regulation is that it provides scan tool manufacturers
with the capability to access data from any make or
model vehicle that is sold.
The data displayed on the other scan tool will appear the
same, with some exceptions. Some scan tools will only
be able to display certain vehicle parameters as values
that are a coded representation of the true or actual val-
ue. On this vehicle, the scan tool displays the actual val-
ues for vehicle parameters. It will not be necessary to
perform any conversions from coded values to actual
values.
EURO ON-BOARD DIAGNOSTIC
(EOBD)
Euro On-Board Diagnostic Tests
A diagnostic test is a series of steps, the result of which
is a pass or fail reported to the diagnostic executive.
When a diagnostic test reports a pass result, the diag-
nostic executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.

The diagnostic test has passed during the current
ignition cycle.

The fault identified by the diagnostic test is not cur-
rently active.
When a diagnostic test reports a fail result, the diagnos-
tic executive records the following data:

The diagnostic test has been completed since the last
ignition cycle.