Open Loop Position Variation

An additional function of the MCU is to correct for changes in ambient conditions (altitude). During closed loop operation, MCU stores movements and positions of metering pins as corrections for oxygen content of exhaust gases are made. If the movements are consistently to the same position, the MCU will vary all open loop operation preset metering pin positions a corresponding amount. This function allows the open loop air/fuel mixture ratios to be adjusted to existing ambient condition during each uninterrupted use of the system. This optimizes emission control and engine performance.