ASVAB Automotive Information Practice Test 786517

Questions 5
Topics Air-Fuel Mixture, Ignition Coil, Intake Manifold, Sensors, Transfer Case

Study Guide

Air-Fuel Mixture

The stoichiometric ratio defines the proper ratio of air to fuel necessary so that an engine burns all fuel with no excess air. For gasoline fuel, the stoichiometric ratio is about 14.7:1 or for every one gram of fuel, 14.7 grams of air are required. Too much air results in a lean air-fuel mixture that burns more slowly and hotter while too much fuel results in a rich mixture that burns quicker and cooler.

Ignition Coil

The ignition coil is a high-voltage transformer made up of two coils of wire. The primary coil winding is the low-voltage winding and has relatively few turns of heavy wire. The secondary coil winding is the high-voltage winding that surrounds the primary and is made up of thousands of turns of fine wire. Current flows from the battery through the primary coil winding which creates a changing magnetic field inside the secondary coil. This induces a very high-voltage current in the secondary coil which it feeds to the distributor.

Intake Manifold

The intake manifold distributes outside air to the intake ports on the cylinder heads. The intake air filter removes any airborne contaminants before the air enters the engine.

Sensors

Sensors provide the data necessary for the vehicle's computer to make decisions and monitor everything from simple vehicle information like tire pressure to complexities like the chemical content of an engine's exhaust.

Transfer Case

The transfer case splits engine power between the front and rear axles of four-wheel drive vehicles.