Feedback System

ECU calculates base injection pulse width by processing signals from the crankshaft angle sensor and mass airflow meter. After receiving signals from sensors detecting engine conditions, ECU adds fuel enrichment (preprogrammed into the control unit) to the base injection width to obtain optimum fuel mixture for all operating conditions. Fuel enrichment is always available under the following conditions: during warm-up, starting, off idle, under heavy load and when engine temperature is high.

This fuel injection system incorporates mixture ratio feedback. It is designed to maintain a precise mixture ratio. Through the use of a Zirconia (4-cylinder) or Titania (V6) exhaust gas sensor located in the exhaust manifold, ECU can adjust air/fuel ratio to optimally control exhaust emissions and engine performance. This function takes place during closed loop operation and continuously monitors itself to stay within an acceptable emissions output range. However, this feedback system can be overridden and will operate in open loop when one or more of the following conditions exist:

• 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 is activated
• Exhaust gas temperature sensor is malfunctioning or vehicle is decelerating.