Feedback System

ECM calculates injection pulse width by processing input signals from ECT, HO2S, TP, MAF and other sensors. After receiving signals from sensors detecting engine conditions, ECM can adjust air/fuel ratio to optimally control exhaust emissions and engine performance.

Fuel injection system incorporates mixture ratio feedback. It is designed to maintain a precise mixture ratio. Through input signals from the front and rear Heated Oxygen Sensors (HO2S), ECM 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:

• Acceleration or deceleration.
• Starting.
• Warm-up.
• High-speed and heavy load conditions.
• High engine coolant temperature.
• Malfunction of front HO2S or circuit
• Front HO2S cold.