Daewoo MATIZ, Service Manual

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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:
D
Engine load (manifold pressure or vacuum).
D
Atmospheric (barometric) pressure.
D
Engine temperature.
D
Intake air temperature.
D
Crankshaft position.
D
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