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 Mixer Governor Fuel Lock-Off Engine Muffler LP Converter VR Sensor Coolant Sensor Small Engine Control Module (SECM) TMAP Sensor Acceleration pedal Angle Sensor Oxygen Sensor Fuel Trim Valve Smart Coil Fuel Lock-Off LP Converter LP Mixer Electronic Throttle Engine Catalytic Muffler G420E/G424E Tier LP Engine System Operational Overview 16