•  The PCM controls the exhaust shutter valve when burning a lean air-fuel mixture.

•  The valve is controlled variably according to the engine conditions to create optimum conditions inside the cylinder for burning a lean air-fuel mixture.

•  The PCM determines the optimum exhaust shutter valve opening angle according to the engine operation conditions and controls the output to the exhaust shutter valve so that the actual valve opening angle reaches the target valve opening angle.

•  When burning a lean air-fuel mixture:

•  When not burning a lean air-fuel mixture:

•  Calculated from the exhaust shutter valve position sensor based on the fully-closed learning value.