Feedback System

ECU calculates base injection pulse width by processing signals from crankshaft angle sensor and mass airflow meter, which detect various engine conditions. After receiving signals from each sensor, ECU adds fuel enrichments (preprogrammed into control unit) to base injection width. This provides optimum mixture for a wide variety of operating conditions. Fuel enrichment is always available under the following engine conditions: warm-up, starting, off idle, heavy load and high cylinder head temperature.

Fuel injection system incorporates mixture ratio feedback. It is designed to maintain a precise mixture ratio. Through use of a Zirconia (G20 and Q45) or Titania (M30) exhaust gas O2 sensor in exhaust manifold, ECU can decide whether to enrich or reduce air/fuel ratio to precisely control exhaust emissions and engine performance. This function takes place during closed loop operation. ECU continuously monitors itself to stay within an acceptable emission output range. However, this feedback system can be overridden and will operate in open loop when one or more of the following conditions exist: engine starting, engine and/or exhaust sensor cold, driving at high speeds or under heavy load, idling, exhaust gas sensor monitors a too rich condition for over 10 seconds, fuel shutoff solenoid activated, exhaust gas temperature sensor malfunctioning, or vehicle is decelerating.