ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
Air fuel ratio (Very rich) 10.1 at all speeds
———- Idle Off idle Cruise
HC 250ppm 275ppm 300ppm
CO 3%. 3%. 3%
CO2 7 to 9 all down
O2 .2% all down
What can the possible cause be ?
A. Leaking injector
B. High Map sensor voltage (low pressure reading) (vacuum leak)
C. Stuck open thermostat
D. All the above -
correct answer ✅D
Air fuel ratio (Rich) 10.1 to 12.1 at low speed
————Idle —-Off idle —-Cruise
HC —-150ppm —150ppm ——-100ppm
,ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
CO ——-1.5%. ———1.5%. ———-1.5%
CO2— 7 to 9% —7 to 9% ——11 to 13%
O2 —- .5% ——-.5% ———- 1.0
High Map sensor (vacuum leak)
Leak injectors
Engine oil diluted with gasoline
Excessive crankcase blowby
Stuck open thermostat
And....
What else can cause this condition?
A. Low fuel pressure
B. Bad camshaft
C. High fuel pressure
D. All the above -
correct answer ✅C
Air fuel ratio very lean above 16.1 at all speeds
————Idle —-Off idle —-Cruise
,ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
HC —-200ppm —205ppm ——-250ppm
CO ——-.5%. ———.5%. ———-1.0%
CO2— 7 to 9% —7 to 9% ——7 to 9%
O2 —- 4-5% ——-4-5% ———- 4-5%
Intermittent ignition problems (misfire)
Restricted fuel injector
Low fuel pressure
Vacuum leak
Improper timing
And..
What else could cause this concern?
A. Stuck open thermostat
B. Stuck close thermostat
C. Both b and d
D. Low cylinder compression -
correct answer ✅C
, ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
Air fuel ratio very lean above 16.1 at high speed
————Idle —-Off idle —-Cruise
HC —-100ppm —80ppm ——-50ppm
CO ——-2.5%. ———1.0%. ———-.8%
CO2— 7 to 9% —7 to 9% ——7 to 9%
O2 —- 2-3% ——-2-3% ———- 2-3%
Intermittent ignition problem (misfire)
Restricted fuel injector
Low fuel pressure
Vacuum leak
And
What else can cause this condition?
A. Heated air intake stuck in cold-air position
B. Bad map sensor
C. Incorrect timing
Questions & Answers (Grade A+)
Air fuel ratio (Very rich) 10.1 at all speeds
———- Idle Off idle Cruise
HC 250ppm 275ppm 300ppm
CO 3%. 3%. 3%
CO2 7 to 9 all down
O2 .2% all down
What can the possible cause be ?
A. Leaking injector
B. High Map sensor voltage (low pressure reading) (vacuum leak)
C. Stuck open thermostat
D. All the above -
correct answer ✅D
Air fuel ratio (Rich) 10.1 to 12.1 at low speed
————Idle —-Off idle —-Cruise
HC —-150ppm —150ppm ——-100ppm
,ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
CO ——-1.5%. ———1.5%. ———-1.5%
CO2— 7 to 9% —7 to 9% ——11 to 13%
O2 —- .5% ——-.5% ———- 1.0
High Map sensor (vacuum leak)
Leak injectors
Engine oil diluted with gasoline
Excessive crankcase blowby
Stuck open thermostat
And....
What else can cause this condition?
A. Low fuel pressure
B. Bad camshaft
C. High fuel pressure
D. All the above -
correct answer ✅C
Air fuel ratio very lean above 16.1 at all speeds
————Idle —-Off idle —-Cruise
,ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
HC —-200ppm —205ppm ——-250ppm
CO ——-.5%. ———.5%. ———-1.0%
CO2— 7 to 9% —7 to 9% ——7 to 9%
O2 —- 4-5% ——-4-5% ———- 4-5%
Intermittent ignition problems (misfire)
Restricted fuel injector
Low fuel pressure
Vacuum leak
Improper timing
And..
What else could cause this concern?
A. Stuck open thermostat
B. Stuck close thermostat
C. Both b and d
D. Low cylinder compression -
correct answer ✅C
, ASE L1 Engine Performance Exam
Questions & Answers (Grade A+)
Air fuel ratio very lean above 16.1 at high speed
————Idle —-Off idle —-Cruise
HC —-100ppm —80ppm ——-50ppm
CO ——-2.5%. ———1.0%. ———-.8%
CO2— 7 to 9% —7 to 9% ——7 to 9%
O2 —- 2-3% ——-2-3% ———- 2-3%
Intermittent ignition problem (misfire)
Restricted fuel injector
Low fuel pressure
Vacuum leak
And
What else can cause this condition?
A. Heated air intake stuck in cold-air position
B. Bad map sensor
C. Incorrect timing
