Intake systems — main purpose of an engine air cleaner (air filter) In a road vehicle, what is the principal function of the engine’s air cleaner assembly located upstream of the throttle/air-meter?

Introduction / Context:
Combustion engines consume large volumes of air that may carry dust, sand, pollen, and other particulates. The air cleaner is a critical first line of defense preventing abrasive particles from damaging the cylinders, piston rings, and turbocharger compressors.

Given Data / Assumptions:

• Pleated paper or synthetic media element in a sealed airbox.
• Properly maintained filter with correct fitment and sealing gaskets.
• Normal on-road or off-road dusty environments.

Concept / Approach:
Filtration removes contaminants above a target particle size while keeping pressure drop within allowable limits. Clean intake air reduces wear, maintains sensor accuracy (MAF/MAP), and protects turbocharger blades from erosion.

Step-by-Step Solution:

Verification / Alternative check:
Oil analysis shows lower silicon (dust) levels with proper filtration; visual inspection of throttle bodies and compressor wheels reveals less contamination when filters are sound.

Why Other Options Are Wrong:

• Controlling air volume: primarily managed by throttle or ECU; filter only imposes a pressure drop.
• Noise reduction and rain ingress prevention: secondary benefits, not the main purpose.
• Increasing boost: the filter cannot raise boost; excessive restriction reduces it.

Common Pitfalls:
Running without a filter, using oiled filters that foul MAF sensors, or installing with leaks that bypass the media.

Final Answer: