2023 Edition

ASE A8 Practice Test

Take this ASE A8 practice test with fully explained answers and instant scoring.  It is based on topics in the real exam.  ASE identifies engine performance as an individual service area. The engine performance service area involves the components listed below.

  • The ignition system -Components that ignite the fuel and air mixture at the proper time to create maximum power and minimum emissions.
  • The fuel system -Components that transfer fuel from the fuel tank to the engine cylinders in the proper amounts so as to create maximum power and minimum emissions.
  • The exhaust system -Components that remove combustion by-products from the engine.
  • The emission control system -Components that reduces the amount of harmful gases emitted from the vehicle.

Tests.com's ASE Test Prep material was written by Dr. John Kershaw, ASE test prep expert: ASE test question developer; ASE Certified Master Technician; ASE Master Truck Technician; and Auto Industry Technical Instructor.  Dr. Kershaw was among the first to receive ASE certification in 1972. 

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General Engine Diagnosis

1. Which of the following should be the first step in diagnosing an engine performance concern?
2. Using a diagnostic strategy for a drivability concern, which of the following is generally the last step in that process?
3. Technician A says paper service manuals are still used in today's service world. Technician B says to follow the recommended service procedures contained in the on-line service information. Who is right?
4. When looking for specific service information, what vehicle information is needed to locate the information?

Ignition Systems Diagnosis and Repair

5. A NO START condition is being diagnosed on a vehicle with electronic fuel injection (EFI) and distributorless ignition. Technician A says you should only use a DMM (Digital Multimeter) to check voltage values on PCM (Powertrain Control Module). Technician B says you should use a tool to check for spark at one of the spark plugs. Who is right?
6. What is being done in the illustration?

7. Technician A says an engine could misfire under load if the ignition coil is tracked. Technician B says the pickup coil must dielectric grease under it. Who is right?
8. A 12 volt test light is connected from the negative primary coil terminal to ground on an electronic distributor ignition (DI) system. The light flutters while cranking the engine. A spark tester does not fire when it is connected from the coil secondary wire to ground while cranking the engine. Which of the following is the MOST likely cause?

Fuel, Air Induction and Exhaust Systems Diagnosis and Repair

9. Two technicians are discussing emission diagnosis. Technician A says an ignition misfire will increase CO and HC emissions and set a DTC (Diagnostic Trouble Code). Technician B says a misfire caused by a lean condition will increase HC and CO emissions without a DTC set. Who is right?
10. A scan tool is being used to check fuel injector balance. Based on service manual procedure, what is the expected result if the injector is functioning properly?
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11. During an injector power balance test, a technician finds one injector has failed but is receiving a good power supply. What should be done next?
12. Which of the following could cause a vehicle to run poorly after the battery was discharged or disconnected?

Emission Control Systems Diagnosis and Repair

13. Technician A says a crushed PCV hose affects idle on some engines and also can cause an oil leak. Technician B says when checking crankcase pressure at 2500 RPM, the PCV system should show a slight pressure in the crankcase at idle. Who is right?
14. Technician A says if the PCV valve is clogged, the engine could have a rough idle. Technician B says if the PCV valve rattles, then it does not need to be replaced. Who is right?
15. A technician suspects the EGR (Exhaust Gas Recirculation) valve is closed. Which of the following would indicate a closed EGR valve?
16. The plastic sensors on an electronically controlled EGR valve have melted. Technician A says excessive back pressure caused by a partially clogged exhaust system could be the cause. Technician B says to always check for a restricted exhaust whenever replacing a failed EGR valve sensor. Who is right?

Computerized Engine Controls Diagnosis and Repair

17. This question has the word EXCEPT. For this question, look for the choice that could NOT meet the described situation. Read the entire question carefully before choosing your answer. Long-term fuel trim is a Self-Learned value. Disconnecting the MAF sensor or using a scan tool can clear a learned value. Many fuel system and emission components have a direct effect on the air/fuel mixture ratio. Self-Learning Control should be cleared each time any of these components have been replaced or repaired, EXCEPT:
18. The OBD II (On Board Diagnostic Level 2) system on a vehicle interprets a disconnected spark plug as a misfire that could damage the three-way catalyst. On which trip will the ECM or PCM MOST likely turn on the Malfunction Indicator Lamp (MIL)?
19. Technician A says the on-board self-diagnostics test mode procedures should be conducted on a cold engine. Technician B says many diagnostic trouble codes (DTC) will monitor items only when the engine control system is in closed loop. Who is right?
20. What component does the PCM or ECM monitor to determine the condition of the catalytic converter and will set a DTC (Diagnostic Trouble Code) if it fails?

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Written by:
Dr. John Kershaw
ASE Test Prep Expert

ASE Test Question Developer

ASE Certified Master Technician

ASE Master Truck Technician

Auto Industry Technical Instructor

Among first ASE Certified in 1972
Actual ASE A6 Topics

• General Electric/Electronic 
• Battery and Starting Systems
• Charging Systems
• Lighting Systems
• Instrument Cluster/ Driver Info.
• Body Electrical Systems 


Number of Questions on the Actual ASE A Series Tests

A1 – Engine Repair (60)
A2 – Automatic Transmission/Transaxle (60)
A3 – Manual Drive Train & Axles (50)
A4 – Suspension & Steering (50)
A5 – Brakes (55)
A6 – Electrical/Electronic Systems (60)
A7 – Heating & Air Conditioning (60)
A8 – Engine Performance (60)
A9 – Light Vehicle Diesel Engines (60)