ASE Prep Lab

ASE A8 Engine Performance — Free Course & Practice Test

The complete ASE A8 course, free on YouTube: 42 video lessons built from ASE's published A8 task list, with a printable workbook for every module. The ASE A8 exam itself is 60 questions (50 scored + 10 unscored) in 75 minutes.

Engine diagnosis, ignition, fuel and air, emissions, and computer controls — the complete A8.

Course modules — watch free on YouTube

Printable workbooks (Etsy)

Prefer to study on paper? Each module has a printable follow-along workbook with worksheets and practice questions drawn from the same 300-question bank as the video course.

ASE A8 practice test — sample questions

Seven questions from the ASE A8 question bank, spread across the modules. Pick your answer, then open the reveal to check it and read the explanation.

Sample question 1 (QA-19, Module 1)

A hissing/whistling sound from the exhaust area with a noticeable power loss at higher rpm suggests:

  1. Exhaust restriction (collapsed muffler baffle or damaged converter substrate)
  2. A vacuum leak
  3. A worn water pump bearing
  4. An ignition misfire
Show answer

Answer: A. A restricted exhaust chokes flow — the engine falls flat as rpm and exhaust volume rise, often with audible backpressure hiss. Distractors: B affects idle quality most. C is a front-of-engine noise. D causes popping/shake, not flow hiss. Source: Tasks A5/C13.

Sample question 2 (QA-55, Module 1)

Low oil pressure at hot idle on a high-mileage engine, with correct oil level and grade, most likely indicates:

  1. Worn engine bearings (increased clearances) or a worn oil pump — a base engine condition, per the manufacturer's pressure specification
  2. A restricted PCV valve
  3. A faulty oxygen sensor
  4. Excessive valve lash
Show answer

Answer: A. Hot, thin oil plus enlarged bearing clearances drops pressure at low pump speed; the reading is judged against the published specification. Distractors: B affects crankcase ventilation, not gallery pressure. C is fuel control. D is valve train clearance, unrelated to oil pressure. Source: Task A13.

Sample question 3 (QB-13, Module 2)

DTC P0300 (random/multiple cylinder misfire) with no single-cylinder code most often directs diagnosis toward:

  1. Causes shared by multiple cylinders: fuel pressure/volume, air measurement, EGR faults, vacuum leaks, or ignition supply — rather than one cylinder's parts
  2. One spark plug
  3. One coil
  4. One injector
Show answer

Answer: A. A random misfire code is by definition not localized; the diagnostic path starts with systems common to all cylinders. Distractors: B, C, and D are single-cylinder parts that would typically set a cylinder-specific P030x code. Source: Task B2.

Sample question 4 (QB-37, Module 2)

Before replacing a coil that shows no output, the technician must verify:

  1. Primary power, ground, and trigger signal at the coil — a coil cannot be condemned until its inputs are proven
  2. Tire condition
  3. The A/C charge
  4. The oxygen sensor
Show answer

Answer: A. No output with missing input is a circuit fault wearing a coil's clothes; inputs first is the standing rule for every component. Distractors: B, C, and D are unrelated systems. Source: Task B5.

Sample question 5 (QC-28, Module 3)

Fuel pressure drops to zero immediately when the pump stops. The vehicle also has long crank times after sitting. Likely causes include:

  1. A leaking pump check valve, a leaking regulator, or a leaking injector — the rail is not holding prime
  2. A weak alternator
  3. A restricted exhaust
  4. Worn spark plugs
Show answer

Answer: A. Holding prime after shutdown is the check valve/regulator/injectors' job; overnight drain-back is the long crank. Distractors: B affects running voltage. C affects power. D affects spark quality, not rail hold. Source: Task C6.

Sample question 6 (QD-25, Module 4)

Technician A says a converter can be damaged by an engine misfire that sends unburned fuel into the exhaust. Technician B says leaded fuel or certain sealant/contamination exposures can poison a converter's washcoat without melting it. Who is right?

  1. A only
  2. B only
  3. Both A and B
  4. Neither A nor B
Show answer

Answer: C. Both failure families are real: thermal destruction from burning fuel, and chemical poisoning that kills oxygen storage while the brick looks intact. Distractors: A-only and B-only each omit a genuine mechanism. Neither denies documented converter failure modes. Source: Task D9 (AIR/CAT).

Sample question 7 (QE-40, Module 5)

A MAF sensor's output should be validated by:

  1. Comparing its reading (grams/second or frequency/voltage) at idle and at a specified rpm/load against the manufacturer's expected values, and checking for a smooth rise with throttle
  2. Shaking it
  3. Measuring its weight
  4. Checking the tire pressures
Show answer

Answer: A. MAF accuracy is judged against expected airflow for the condition; a smooth, plausible-but-low curve is the contaminated sensor's signature. Distractors: B and C are meaningless tests. D is a different system. Source: Task E5.

All 300 questions for ASE A8 — with full answer keys — are in the printable workbooks above, and every one is worked through in the free video lessons.