A8 Engine Performance Practice Tests

A8 Engine Performance – What the Test Covers

The A8 test is 50 scored questions in 75 minutes. Computerized engine controls and general diagnosis together carry half the exam, which tells you what this test really is: not a parts-replacement test, but a test of whether you can work a driveability complaint from symptom to cause.

Content areas and their weighting below come straight from the 2026 Official ASE Study Guide task list. Every question on this site was written against one of these tasks, and the four tests in this subject are weighted to match.

Content Areas on the A1 Test:

• General Diagnosis24% OF TEST
  12 questions. Verifying the complaint, visual inspection and road testing, researching engine management service information and TSBs, diagnosing base engine mechanical problems, noise and vibration diagnosis, unusual exhaust color, odor and sound, manifold vacuum and pressure tests, cylinder power balance, cranking, relative and running compression tests, cylinder leakage testing, diagnosis with an oscilloscope, DMM or scan tool, verifying valve adjustment on mechanical and hydraulic lifter engines, and verifying camshaft timing and the operation of timing components including variable valve timing.
• Ignition System Diagnosis and Repair16% OF TEST
  8 questions. Diagnosing no-start, hard start, engine misfire, poor driveability, spark knock, power loss, poor mileage and emissions failures that trace to ignition, interpreting ignition-related DTCs, primary circuit wiring, connectors, sensors and modules, secondary circuit wiring, coils and plugs, ignition coil testing and replacement, ignition system sensor testing and adjustment, and ignition control module and PCM service.
• Fuel, Air Induction and Exhaust Systems Diagnosis and Repair18% OF TEST
  9 questions. Diagnosing hot and cold no-start, hard start, misfire, poor driveability, spark knock, power loss and emissions failures caused by the fuel system, interpreting fuel and air induction DTCs, fuel tank, filler neck, cap, lines and filters, fuel pump and pump assembly testing and replacement, fuel pump control circuits, fuel pressure regulation, throttle assembly service and adjustment, injector testing and cleaning including high-pressure lines and rails, air filtration components, vacuum leaks, restrictions and unmetered air, and exhaust manifolds, pipes, oxygen sensors and converters.
• Emissions Control Systems Diagnosis and Repair16% OF TEST
  8 questions, broken out by ASE into specific sub-areas: positive crankcase ventilation (1 question), exhaust gas recirculation (2), secondary air injection and catalytic converter (2), and evaporative emissions controls (3). Each one covers diagnosing emissions or driveability problems caused by that system, interpreting its scan data and DTCs, and inspecting, testing, servicing and replacing both its mechanical components and its electrical and electronic controls.
• Computerized Engine Controls Diagnosis and Repair26% OF TEST
  13 questions — the largest area on the test. Retrieving and recording DTCs, OBD II monitor status and freeze frame data, researching enable criteria for setting and clearing codes, diagnosing driveability and emissions problems both with and without stored codes, using a scan tool, DMM or oscilloscope to test sensors, actuators, circuits and modules, measuring and interpreting voltage, voltage drop, amperage and resistance, voltage supply and ground circuits, PCM and ECM testing, replacement and programming, diagnosing failures caused by interrelated systems, data bus network diagnosis, and clearing codes, running the monitors and verifying the repair.