Step Injection Duration Correction Factors

The second step involves duration corrections. Input sensors used for injection duration corrections are:

• Engine Water Temperature (THW)

• Intake Air Temperature (THA)

• Exhaust Oxygen Content (OX)

Once basic injection duration is calculated, the ECU must modify the injection duration based on other changing variables. Variables considered in the correction calculation are coolant and intake air temperature, throttle position and exhaust oxygen sensor feedback (when operating in closed loop).

• As engine and intake air temperatures move from cold to warm, injection duration is reduced.

• As the throttle opens (IDL contact break), injection frequency is momentarily increased.

• Fuel injection duration swings back and forth between longer to shorter durations to correct conditions detected by the exhaust oxygen sensor.

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Do It Yourself Car Diagnosis

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