Mi-04 Ignition Management - Daewoo G420E Service Manual

MI-04 Ignition management

In the normal course of events, with the engine
operating at the correct temperature in defined
conditions, the SECM will use load and engine speed
to derive the correct ignition timing. In addition to load
and speed there are other circumstances under which
the SECM may need to vary the ignition timing,
including low engine coolant temperature, air
temperature, start-up, idle speed control.
VR Sensor
Figure 31
(1) Timing Wheel (2) VR Sensor
A Variable Reluctance sensor (Figure 31) is an
electromagnetic device consisting of a permanent
magnet surrounded by a winding of wire. The sensor
is used in conjunction with a ferrous timing wheel
located on the crankshaft pulley. The timing wheel is
referred to as 30-5 ignition because the wheel has 30
gear teeth with 5 removed at precise locations, giving
the SECM a very accurate speed reference signal.
Rotation of the timing wheel near the tip of the sensor
changes the magnetic flux, creating an analog
voltage signal in the sensor coil.
Ignition Coil (Smart Coil)
The MI-04 system is capable of operating with either
a distributor based ignition system or a distributor less
ignition system. The current application uses a
distributor based ignition system. The distributor will
have no internal advance mechanisms giving the
SECM consistent authority over ignition timing. The
spark is sent to the appropriate cylinder in the
conventional way via the rotor arm and spark plug
wires. The SECM uses the signal from the VR
(Variable Reluctance) sensor mounted near the
crankshaft pulley to determine the engine position
and RPM at any time. It uses this information together
with the information from the TPS sensor and TMAP
to calculate the appropriate ignition timing settings for
the "smart coil".
Tier
G420E/G424E
1
2
LP Engine
The MI-04 system uses a single coil, which
incorporates the ignition driver circuitry inside the coil
itself. The SECM signals the "smart coil" when to
begin its dwell cycle then the coil waits for the trigger
signal from the SECM.
The "smart coil" eliminates the need for a driver circuit
inside the SECM or externally from the coil. Using a
single VR sensor and "smart coil" eliminates multiple
sensors and coil packs used in more complex ignition
systems.
Distributor
The distributor of G420/G424 engine has the
mechanical advance system internally. But the new
distributor of G420E/G424E engine has no internal
advance mechanisms.
A333011: Distributor assy for G420E/G424E engines
A218350: Distributor assy for G420/G424 engines
29
"SmartCoil"
System Operational Overview