Automotive Service Excellence (ASE) L1
Advanced Engine Performance Verified
Questions and Answers
1.
A 2021 BMW M3 exhibits intermittent misfire at high RPM. Technician observes spark plugs
worn and ignition coils within specification. What is the first correct step?
A. Replace spark plugs only
B. Replace fuel injectors
C. Perform fuel pressure and injector pulse test
D. Replace ECM
Correct Answer: C
Rationale:
Misfire under load can be caused by fuel delivery issues. Testing fuel pressure and injector
operation identifies the root cause before replacing components unnecessarily.
2.
A turbocharged 2020 Mercedes C-Class shows high exhaust temperatures and slight engine
knocking. Technician notes a lean air-fuel ratio at full load. Correct repair:
A. Replace fuel injectors
B. Inspect and clean MAF sensor, check boost leaks
C. Replace turbocharger
D. Replace spark plugs
Correct Answer: B
Rationale:
Lean AFR can result from air leaks or faulty sensors, causing knock and high exhaust
temperature. Fixing intake leaks and sensor faults prevents unnecessary replacements.
,3.
A 2019 Ford F-150 with a V6 EcoBoost exhibits surging at idle. Scan tool shows fluctuating fuel
trims. Technician should first:
A. Replace fuel pump
B. Inspect for vacuum leaks and intake leaks
C. Replace IAC valve
D. Replace throttle body
Correct Answer: B
Rationale:
Surging with fluctuating fuel trims is usually caused by unmetered air entering the engine, often
due to vacuum or intake leaks.
4.
A 2022 Toyota Supra exhibits rough acceleration and CEL P0302 (cylinder 2 misfire). Spark
plugs and ignition coil are new; compression is normal. Technician observes injector pulse is
irregular. Correct repair:
A. Replace spark plug
B. Replace fuel injector for cylinder 2
C. Replace ECM
D. Replace ignition coil
Correct Answer: B
Rationale:
Irregular injector pulse is a direct cause of a misfire. Replacing the injector resolves the issue
without unnecessary replacement of other components.
5.
,A 2020 Honda Accord shows hesitation on acceleration. Fuel trims show +25% at wide-open
throttle. Technician should first:
A. Replace fuel pump
B. Check for air intake restrictions and MAF sensor contamination
C. Replace throttle body
D. Replace spark plugs
Correct Answer: B
Rationale:
High positive fuel trims indicate the engine is compensating for a lean condition, commonly
caused by intake air issues. Cleaning or repairing intake fixes the problem.
6.
A diesel engine has black smoke under acceleration. Fuel pressure and injectors are within
specification. Technician notices clogged EGR cooler. Correct step:
A. Replace injectors
B. Clean or replace EGR cooler
C. Replace turbocharger
D. Replace fuel pump
Correct Answer: B
Rationale:
Restricted EGR flow increases soot and black smoke. Cleaning or replacing the EGR cooler
corrects emissions without unnecessary fuel system replacement.
7.
A 2021 Chevrolet Camaro exhibits hesitation under load. Scan data shows misfire codes P0301
and P0303. Technician observes both cylinder coils are new; spark plugs are 70,000 miles old.
Correct repair:
A. Replace coils
B. Replace spark plugs
, C. Replace fuel injectors
D. Replace ECM
Correct Answer: B
Rationale:
Aged spark plugs are a common cause of multiple cylinder misfires under load; replacing them
corrects the issue.
8.
A 2022 Ford Mustang EcoBoost exhibits knocking under full throttle. Technician finds low
octane fuel was recently used. Correct step:
A. Replace spark plugs
B. Clear codes and advise higher octane fuel
C. Replace knock sensors
D. Replace ECM
Correct Answer: B
Rationale:
Engine knock from low octane fuel is not a mechanical fault. Using correct fuel and clearing
codes resolves the issue.
9.
A 2019 Toyota Tacoma V6 exhibits excessive fuel consumption. Technician notes short-term
fuel trims are consistently +15% at idle. Likely cause:
A. Clogged fuel filter
B. Intake vacuum leak
C. Worn spark plugs
D. Faulty O2 sensor
Correct Answer: B
Advanced Engine Performance Verified
Questions and Answers
1.
A 2021 BMW M3 exhibits intermittent misfire at high RPM. Technician observes spark plugs
worn and ignition coils within specification. What is the first correct step?
A. Replace spark plugs only
B. Replace fuel injectors
C. Perform fuel pressure and injector pulse test
D. Replace ECM
Correct Answer: C
Rationale:
Misfire under load can be caused by fuel delivery issues. Testing fuel pressure and injector
operation identifies the root cause before replacing components unnecessarily.
2.
A turbocharged 2020 Mercedes C-Class shows high exhaust temperatures and slight engine
knocking. Technician notes a lean air-fuel ratio at full load. Correct repair:
A. Replace fuel injectors
B. Inspect and clean MAF sensor, check boost leaks
C. Replace turbocharger
D. Replace spark plugs
Correct Answer: B
Rationale:
Lean AFR can result from air leaks or faulty sensors, causing knock and high exhaust
temperature. Fixing intake leaks and sensor faults prevents unnecessary replacements.
,3.
A 2019 Ford F-150 with a V6 EcoBoost exhibits surging at idle. Scan tool shows fluctuating fuel
trims. Technician should first:
A. Replace fuel pump
B. Inspect for vacuum leaks and intake leaks
C. Replace IAC valve
D. Replace throttle body
Correct Answer: B
Rationale:
Surging with fluctuating fuel trims is usually caused by unmetered air entering the engine, often
due to vacuum or intake leaks.
4.
A 2022 Toyota Supra exhibits rough acceleration and CEL P0302 (cylinder 2 misfire). Spark
plugs and ignition coil are new; compression is normal. Technician observes injector pulse is
irregular. Correct repair:
A. Replace spark plug
B. Replace fuel injector for cylinder 2
C. Replace ECM
D. Replace ignition coil
Correct Answer: B
Rationale:
Irregular injector pulse is a direct cause of a misfire. Replacing the injector resolves the issue
without unnecessary replacement of other components.
5.
,A 2020 Honda Accord shows hesitation on acceleration. Fuel trims show +25% at wide-open
throttle. Technician should first:
A. Replace fuel pump
B. Check for air intake restrictions and MAF sensor contamination
C. Replace throttle body
D. Replace spark plugs
Correct Answer: B
Rationale:
High positive fuel trims indicate the engine is compensating for a lean condition, commonly
caused by intake air issues. Cleaning or repairing intake fixes the problem.
6.
A diesel engine has black smoke under acceleration. Fuel pressure and injectors are within
specification. Technician notices clogged EGR cooler. Correct step:
A. Replace injectors
B. Clean or replace EGR cooler
C. Replace turbocharger
D. Replace fuel pump
Correct Answer: B
Rationale:
Restricted EGR flow increases soot and black smoke. Cleaning or replacing the EGR cooler
corrects emissions without unnecessary fuel system replacement.
7.
A 2021 Chevrolet Camaro exhibits hesitation under load. Scan data shows misfire codes P0301
and P0303. Technician observes both cylinder coils are new; spark plugs are 70,000 miles old.
Correct repair:
A. Replace coils
B. Replace spark plugs
, C. Replace fuel injectors
D. Replace ECM
Correct Answer: B
Rationale:
Aged spark plugs are a common cause of multiple cylinder misfires under load; replacing them
corrects the issue.
8.
A 2022 Ford Mustang EcoBoost exhibits knocking under full throttle. Technician finds low
octane fuel was recently used. Correct step:
A. Replace spark plugs
B. Clear codes and advise higher octane fuel
C. Replace knock sensors
D. Replace ECM
Correct Answer: B
Rationale:
Engine knock from low octane fuel is not a mechanical fault. Using correct fuel and clearing
codes resolves the issue.
9.
A 2019 Toyota Tacoma V6 exhibits excessive fuel consumption. Technician notes short-term
fuel trims are consistently +15% at idle. Likely cause:
A. Clogged fuel filter
B. Intake vacuum leak
C. Worn spark plugs
D. Faulty O2 sensor
Correct Answer: B
