G420E/G424E
Tier
LP Engine
System Operational Overview
16
The SECM makes any necessary corrections to the air fuel ratio by controlling the inlet fuel pressure to the air/fuel
mixer by modulating the fuel trim valve (FTV) connected to the regulator. Reducing the fuel pressure leans the
air/fuel mixture and increasing the fuel pressure enriches the air/fuel mixture. To calculate any necessary
corrections to the air fuel ratio, the SECM uses a number of different sensors to gain information about the engines
performance. Engine speed is monitored by the SECM through a variable reluctance (VR) sensor. Intake manifold
air temperature and absolute pressure is monitored with a (TMAP) sensor. The MI-04 is a drive by wire (DBW)
system connecting the accelerator pedal to the electronic throttle through the electrical harness, mechanical
cables are not used. A throttle position sensor (TPS) monitors throttle position in relation to the accelerator pedal
position sensor (APP) feedback. Even engine coolant temperature is monitored by the SECM. The SECM
controller has full adaptive learning capabilities, allowing it to adapt control function as operating conditions change.
Factors such as ambient temperature, fuel variations, ignition component wear, clogged air filter, and other
operating variables are compensated.
Open Loop LP Fuel System
G420/G424 Open Loop LP Fuel System
MI-04 Closed Loop LP Fuel System
G420E/G424E Closed Loop LP Fuel System
LP
Converter
LP
Mixer
Governor
Fuel
Lock-Off
Engine
Muffler
Small
Engine
Control
Module
(SECM)
Fuel Trim
Valve
LP
Converter
LP
Mixer
Electronic
Throttle
Smart Coil
VR
Sensor
TMAP
Sensor
Oxygen
Sensor
Fuel
Lock-Off
Coolant
Sensor
Engine
Catalytic
Muffler
Acceleration
pedal
Angle
Sensor
