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ASE Automobile & Light Truck (A1–A8) — Practice Exam

A8 Fuel, air and exhaust: practice questions

Our ASE A1–A8 bank has 9 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.

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Question 1 · A8 Engine Performance

What does a mass airflow (MAF) sensor measure?

  1. Manifold vacuum and barometric pressure
  2. Throttle angle
  3. Exhaust oxygen
  4. The amount of air entering the engine
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D. The amount of air entering the engine — A contaminated MAF can under-report airflow and cause lean conditions.

Question 2 · A8 Engine Performance

What is a common issue with gasoline direct injection engines over time?

  1. Carbon build-up on intake valves
  2. Fuel washing the cylinder walls
  3. Excess oil pressure
  4. Rapid spark plug wear from fuel spray
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A. Carbon build-up on intake valves — Fuel no longer washes the back of the intake valves.

Question 3 · A8 Engine Performance

How can a clogged fuel injector be identified?

  1. Checking the oil level
  2. Injector balance (pressure drop) test or a cylinder contribution test
  3. Checking fuel tank level
  4. Measuring battery voltage and injector resistance on all cylinders at once
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B. Injector balance (pressure drop) test or a cylinder contribution test — A clogged injector causes a lean misfire on that cylinder.

Question 4 · A8 Engine Performance

How is fuel pump volume tested?

  1. By listening to the pump
  2. By measuring pump resistance and current draw with the key on and the engine off
  3. By checking fuel color
  4. By measuring how much fuel is delivered in a set time
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D. By measuring how much fuel is delivered in a set time — Pressure alone doesn't show if the pump can deliver enough volume.

Question 5 · A8 Engine Performance

Why is high pressure a hazard on gasoline direct injection systems?

  1. They run on vacuum
  2. They only use low pressure from the in-tank pump, about 50 psi at most
  3. They use no pressure
  4. Pressures can exceed 2,000 psi and must be relieved before service
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D. Pressures can exceed 2,000 psi and must be relieved before service — Follow the maker's depressurizing procedure.

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