ICE-20 — The Air Path

ASSUMPTION — This lesson covers the air path conceptually; specific sensor/actuator values are not given.

In this lesson you will learn:

• The air-path components
• Air-mass flow measurement
• Boost and load control

1. Components

Air flows: air filter → MAF sensor → turbo compressor → intercooler → throttle (gasoline) → intake manifold → intake valve → cylinder.

FACT — In gasoline engines the throttle controls load; a diesel usually has no throttle (or a minor one), with load set by injected quantity.

2. Air-Mass Flow Measurement

FACT — The MAF sensor measures inducted air mass; the MAP sensor measures manifold absolute pressure. The ECU uses these to compute the correct fuel quantity.

3. Boost and Load Control

FACT — In turbo systems, boost is controlled by the wastegate/VGT. The ECU manages the air path to deliver the target air quantity derived from the driver’s torque request — the basis of the torque structure (ICE-35).

4. Relation to Emissions

INTERPRETATION — Air-path control works with lambda (ICE-26) and EGR (ICE-19) to manage emissions. If air is mis-measured, the mixture drifts rich or lean, hurting emissions and driveability.

5. Summary

• Path: filter → MAF → turbo → intercooler → throttle → manifold → cylinder.
• MAF/MAP measure air.
• Boost is controlled by wastegate/VGT.
• Air control underpins power and emissions.

6. Sources

• Bosch, Gasoline-Engine Management and Diesel-Engine Management

Next Lesson

• ICE-21 — The Exhaust System.