Engine Control System for a Natural Gas Vehicle

The natural gas vehicle has high potential as a clean alternative fuel vehicle because of its clean burning characteristics. Honda has been developing a dedicated compressed natural gas (CNG) vehicle since 1998. It has achieved near-zero emissions and the 2001 model year Civic GX was the first vehicle to be certified as AT P-ZEV (Advanced Technology, Partial-credit, Zero Emission Vehicle) by the California Air Resources Board (CARB).

A key technology for low emissions is precise air-fuel ratio control. We adopted a fuel supply system with multi-point injectors and 2-stage pressure regulators. A power control module (PCM) calculates the fuel injection rate by receiving signals from the fuel pressure sensor and the fuel temperature sensor. The PCM maintains an optimum air-fuel ratio using two newly developed heated oxygen sensors.