What does the MAP sensor read at idle under no load?

The MAP (Manifold Absolute Pressure) sensor measures the pressure within the intake manifold of an engine, which is crucial for the engine control unit (ECU) to calculate the proper air-fuel mixture for combustion. At idle under no load conditions, the pressure in the manifold is typically lower than atmospheric pressure due to the vacuum created by the engine's intake process.

The correct choice reflects a common voltage output of a MAP sensor at idle, which often ranges around 1.1 to 1.3 volts, corresponding to the low manifold pressure typical in these conditions. The value of 1.17V is consistent with the operational characteristics of a MAP sensor functioning correctly during idle, indicating a sufficient vacuum signal for the ECU to make necessary adjustments for fuel delivery and ignition timing.

The other options present different voltage levels that, while they might be relevant under different operating conditions or specific engine designs, do not accurately represent the typical MAP sensor reading at idle without load. Each engine might exhibit slightly varied outputs, but the selected answer aligns well with standard figures observed in automotive applications.