The BARO sensor makes up for altitude by either adding or subtracting from the base duty cycle.

The BARO sensor makes up for altitude by either adding or subtracting from the base duty cycle.

• A. BARO sensor
• B. IAT sensor
• C. MAF sensor
• D. MAP sensor

Answer: (A)

The key idea is that engine fueling at altitude is adjusted using ambient air pressure. The BARO sensor measures the outside atmospheric pressure, which changes with altitude, and the ECU uses that information to modify the injector pulse width that forms the base fueling plan. When ambient pressure drops with higher altitude, air density falls, so the ECU tweaks the base duty cycle—either increasing or decreasing it—to keep the air-fuel ratio around the target. This ambient-pressure input specifically handles altitude compensation, unlike the other sensors: the IAT sensor accounts for intake air temperature effects on density, the MAF sensor measures actual air entering the engine, and the MAP sensor gauges manifold pressure for load, but neither alone provides the ambient pressure signal used toCorrect the base fueling for altitude.

The key idea is that engine fueling at altitude is adjusted using ambient air pressure. The BARO sensor measures the outside atmospheric pressure, which changes with altitude, and the ECU uses that information to modify the injector pulse width that forms the base fueling plan. When ambient pressure drops with higher altitude, air density falls, so the ECU tweaks the base duty cycle—either increasing or decreasing it—to keep the air-fuel ratio around the target. This ambient-pressure input specifically handles altitude compensation, unlike the other sensors: the IAT sensor accounts for intake air temperature effects on density, the MAF sensor measures actual air entering the engine, and the MAP sensor gauges manifold pressure for load, but neither alone provides the ambient pressure signal used toCorrect the base fueling for altitude.