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 Fuel Filter Fault Light Key switch LP Fuel Line Main PWR Relay Vacuum Line Fuel Lock APP Accel Pedal Converter Air Cleaner Coolant Line Fuel Trim Valve Mixer DBW Throttle TPS SECM Oxygen TMAP Catalytic Muffler Distributor Engine VR Sensor Coolant Temp Sensor Figure 10 G420E/G424E Tier LP Engine System Operational Overview 15