What happens to engine operation if the impact-air pressure passage is clogged?

An impact-air pressure passage is critical for the proper functioning of an engine's fuel metering system, as it allows the engine control unit (ECU) to measure the air pressure entering the intake manifold. If this passage becomes clogged, it impairs the engine's ability to receive accurate airflow information, which is essential for adjusting the fuel-to-air mixture.

When the impact-air pressure passage is blocked, the engine may mistakenly process a lower air pressure reading. In response to this incorrect input from the clogged passage, the fuel system compensates by reducing the fuel supply to maintain the air-fuel mixture's proper ratio. At higher power settings, this can lead to a leaner mixture because the engine controls will assume less air is being ingested, resulting in less fuel being injected. Operating with a leaner mixture can lead to efficiency losses and potential preventable engine damage if not addressed.

The other outcomes suggested, such as engine stalling or only being able to run at idle, usually indicate more severe malfunctioning of the engine or its components rather than merely an obstructed impact-air pressure passage.