ASE A8 Engine Performance Exam Questions
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1.
A vehicle has a rough idle and sets a P0300 (random misfire). What is
the MOST likely cause?
A. Faulty thermostat
B. Vacuum leak
C. Low tire pressure
D. Worn brake pads
Answer: B. Vacuum leak
Rationale: A vacuum leak causes a lean condition leading to random
misfires.
2.
,A P0171 code indicates:
A. Rich condition bank 1
B. Lean condition bank 1
C. Misfire cylinder 1
D. O2 sensor heater failure
Answer: B. Lean condition bank 1
Rationale: P0171 means too much air or not enough fuel on bank 1.
3.
Which sensor primarily controls fuel delivery in closed loop?
A. MAP sensor
B. TPS
C. Oxygen sensor
D. CKP sensor
Answer: C. Oxygen sensor
Rationale: The O2 sensor provides feedback for fuel trim adjustments.
4.
A faulty MAF sensor may cause:
A. Lean or rich condition
,B. Brake failure
C. Transmission slipping
D. Coolant leaks
Answer: A. Lean or rich condition
Rationale: The MAF measures airflow; incorrect readings disrupt fuel
mixture.
5.
What does a high short-term fuel trim indicate?
A. Engine running rich
B. Engine running lean
C. Engine overheating
D. Battery low
Answer: B. Engine running lean
Rationale: Positive fuel trim means the PCM is adding fuel.
6.
A no-spark condition could be caused by a faulty:
A. Fuel pump
B. Ignition coil
, C. Oxygen sensor
D. Catalytic converter
Answer: B. Ignition coil
Rationale: The ignition coil generates spark voltage.
7.
Which component provides engine speed data to the PCM?
A. CMP sensor
B. CKP sensor
C. TPS
D. ECT sensor
Answer: B. CKP sensor
Rationale: The crankshaft position sensor determines engine speed.
8.
A clogged fuel filter will cause:
A. Rich condition
B. Lean condition
C. High oil pressure
D. Low coolant temperature
and Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1.
A vehicle has a rough idle and sets a P0300 (random misfire). What is
the MOST likely cause?
A. Faulty thermostat
B. Vacuum leak
C. Low tire pressure
D. Worn brake pads
Answer: B. Vacuum leak
Rationale: A vacuum leak causes a lean condition leading to random
misfires.
2.
,A P0171 code indicates:
A. Rich condition bank 1
B. Lean condition bank 1
C. Misfire cylinder 1
D. O2 sensor heater failure
Answer: B. Lean condition bank 1
Rationale: P0171 means too much air or not enough fuel on bank 1.
3.
Which sensor primarily controls fuel delivery in closed loop?
A. MAP sensor
B. TPS
C. Oxygen sensor
D. CKP sensor
Answer: C. Oxygen sensor
Rationale: The O2 sensor provides feedback for fuel trim adjustments.
4.
A faulty MAF sensor may cause:
A. Lean or rich condition
,B. Brake failure
C. Transmission slipping
D. Coolant leaks
Answer: A. Lean or rich condition
Rationale: The MAF measures airflow; incorrect readings disrupt fuel
mixture.
5.
What does a high short-term fuel trim indicate?
A. Engine running rich
B. Engine running lean
C. Engine overheating
D. Battery low
Answer: B. Engine running lean
Rationale: Positive fuel trim means the PCM is adding fuel.
6.
A no-spark condition could be caused by a faulty:
A. Fuel pump
B. Ignition coil
, C. Oxygen sensor
D. Catalytic converter
Answer: B. Ignition coil
Rationale: The ignition coil generates spark voltage.
7.
Which component provides engine speed data to the PCM?
A. CMP sensor
B. CKP sensor
C. TPS
D. ECT sensor
Answer: B. CKP sensor
Rationale: The crankshaft position sensor determines engine speed.
8.
A clogged fuel filter will cause:
A. Rich condition
B. Lean condition
C. High oil pressure
D. Low coolant temperature
