Automotive Systems (09/10/26)

A MAF sensor becomes contaminated and reports LESS incoming air than is actually entering the engine. What is the most likely result?

The computer commands too little fuel, causing a LEAN mixture.

What does MAF stand for, and what does the sensor do?

Mass Air Flow. It measures how much air is entering the engine so the computer can match the fuel to it.

If a MAF sensor reads LOW (less air than actual), what happens to the mixture?

Less fuel is commanded, so the mixture runs LEAN.

If a MAF sensor reads HIGH (more air than actual), what happens to the mixture?

More fuel is commanded, so the mixture runs RICH.

Remember the MAF rule: cold reading versus hot reading.

Cold reading means more fuel, so richer. Hot reading means less fuel, so leaner.

Why does a contaminated MAF sensor cause a driveability problem rather than an oil or coolant problem?

The MAF only tells the computer how much air is coming in, and the computer's response is to adjust FUEL. It does not control oil pressure or coolant flow.

What does an alternator do?

Produces electricity.

What does a starter solenoid do?

Switches high current to the starter.

What is a rheostat used for in an electrical circuit?

To change resistance in order to control current.

What does a rectifier do?

Changes AC into DC. AC goes in, DC comes out.

What happens if a thermostat is stuck CLOSED?

It blocks coolant from reaching the radiator, so the engine overheats.

What is a PCV valve, and what does it do?

Positive Crankcase Ventilation valve. A small one-way component that controls the flow of escaping gases to prevent dangerous internal pressure.

What is the crankcase?

The area around the crankshaft, where the engine oil is.

What is a tie rod, and what does it connect?

Part of the steering linkage. It connects toward the steering knuckle and wheel assembly.

What does the Pitman arm connect?

The steering gear or steering box to the steering linkage.

Tie rod or Pitman arm — which connects to the steering BOX, and which to the WHEEL?

The Pitman arm connects to the steering box. The tie rod connects toward the wheel.