ASE A8 Engine Performance Practice
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the primary purpose of the oxygen sensor?
A. Measure engine temperature
B. Monitor exhaust oxygen content
C. Control fuel pressure
D. Adjust ignition timing
Answer: B
Rationale: The oxygen sensor measures oxygen in exhaust gases to help
the ECM adjust the air-fuel ratio.
2. A lean air-fuel mixture contains:
A. Too much fuel
B. Too much air
C. Equal air and fuel
D. No oxygen
Answer: B
Rationale: A lean mixture has excess air compared to fuel.
3. What does OBD-II stand for?
A. Onboard Diagnostics II
B. Output Battery Device II
C. Onboard Drive Input
, D. Output Data Bus II
Answer: A
Rationale: OBD-II refers to the second generation of onboard diagnostics
systems.
4. A misfire can be caused by:
A. Excess oil pressure
B. Faulty spark plug
C. Clean air filter
D. Proper fuel pressure
Answer: B
Rationale: A faulty spark plug can prevent proper combustion, causing a
misfire.
5. What sensor measures intake air volume?
A. TPS
B. MAP
C. MAF
D. ECT
Answer: C
Rationale: The Mass Air Flow sensor measures the volume of air entering
the engine.
6. The MAP sensor measures:
A. Fuel pressure
B. Intake manifold pressure
C. Exhaust gas flow
D. Oil level
Answer: B
Rationale: The MAP sensor measures pressure inside the intake manifold.
7. A rich mixture results in:
A. High oxygen content
B. Low fuel consumption
C. Excess fuel in combustion
, D. Engine overheating
Answer: C
Rationale: A rich mixture contains more fuel than necessary.
8. Which component controls ignition timing?
A. Fuel pump
B. ECM
C. Radiator
D. Alternator
Answer: B
Rationale: The Engine Control Module adjusts ignition timing
electronically.
9. A faulty catalytic converter may cause:
A. Increased engine power
B. Reduced emissions
C. Loss of power
D. Better fuel economy
Answer: C
Rationale: A clogged converter restricts exhaust flow, reducing engine
power.
10.The throttle position sensor measures:
A. Engine temperature
B. Throttle angle
C. Fuel pressure
D. Exhaust gases
Answer: B
Rationale: TPS tracks the position of the throttle plate.
11.Engine knocking is often caused by:
A. Lean mixture
B. Incorrect ignition timing
C. Low oil level
D. High coolant level
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A Instant Download Pdf
1. What is the primary purpose of the oxygen sensor?
A. Measure engine temperature
B. Monitor exhaust oxygen content
C. Control fuel pressure
D. Adjust ignition timing
Answer: B
Rationale: The oxygen sensor measures oxygen in exhaust gases to help
the ECM adjust the air-fuel ratio.
2. A lean air-fuel mixture contains:
A. Too much fuel
B. Too much air
C. Equal air and fuel
D. No oxygen
Answer: B
Rationale: A lean mixture has excess air compared to fuel.
3. What does OBD-II stand for?
A. Onboard Diagnostics II
B. Output Battery Device II
C. Onboard Drive Input
, D. Output Data Bus II
Answer: A
Rationale: OBD-II refers to the second generation of onboard diagnostics
systems.
4. A misfire can be caused by:
A. Excess oil pressure
B. Faulty spark plug
C. Clean air filter
D. Proper fuel pressure
Answer: B
Rationale: A faulty spark plug can prevent proper combustion, causing a
misfire.
5. What sensor measures intake air volume?
A. TPS
B. MAP
C. MAF
D. ECT
Answer: C
Rationale: The Mass Air Flow sensor measures the volume of air entering
the engine.
6. The MAP sensor measures:
A. Fuel pressure
B. Intake manifold pressure
C. Exhaust gas flow
D. Oil level
Answer: B
Rationale: The MAP sensor measures pressure inside the intake manifold.
7. A rich mixture results in:
A. High oxygen content
B. Low fuel consumption
C. Excess fuel in combustion
, D. Engine overheating
Answer: C
Rationale: A rich mixture contains more fuel than necessary.
8. Which component controls ignition timing?
A. Fuel pump
B. ECM
C. Radiator
D. Alternator
Answer: B
Rationale: The Engine Control Module adjusts ignition timing
electronically.
9. A faulty catalytic converter may cause:
A. Increased engine power
B. Reduced emissions
C. Loss of power
D. Better fuel economy
Answer: C
Rationale: A clogged converter restricts exhaust flow, reducing engine
power.
10.The throttle position sensor measures:
A. Engine temperature
B. Throttle angle
C. Fuel pressure
D. Exhaust gases
Answer: B
Rationale: TPS tracks the position of the throttle plate.
11.Engine knocking is often caused by:
A. Lean mixture
B. Incorrect ignition timing
C. Low oil level
D. High coolant level
