Service manual

G420E/G424E Tier LP Engine System Operational Overview 15
CHAPTER 2 MI-04 LPG SYSTEM OPERATIONAL
OVERVIEW
MI-04 General Description
MI-04 control system is designed to provide a complete, fully integrated solution that will meet or exceed TIER-2
Large Spark Ignited Engines emission standards established by the California Air Research Board (CARB) and the
Environmental Protection Agency (EPA) for 2004. The MI-04 is a closed loop system utilizing a catalytic muffler to
reduce the emission level in the exhaust gas. In order to obtain maximum effect from the catalyst, an accurate
control of the air fuel ratio is required. A small engine control module (SECM) uses a heated exhaust gas oxygen
sensor (HEGO) in the exhaust system to monitor exhaust gas content.
MI-04 System with the N-CA55-500 Mixer
Figure 10
Key switch
Accel Pedal
Fuel Filter
Fuel Lock
Converter
SECM
Fuel Trim Valve
Mixer
Distributor
Engine
VR Sensor
Coolant Temp Sensor
Catalytic
Muffler
Oxygen
DBW Throttle
Fault Light
Air Cleaner
LP Fuel Line
Coolant Line
TPS
APP
Main
PWR
Relay
Vacuum Line
TMAP