Engine Performance final exam UPDATED
ACTUAL Questions and CORRECT
Answers
Higher compression ratios tend to speed up combustion. - CORRECT ANSWER - true
The MIL light should illuminate when the ignition switch is turned to the run position [engine not
running] and go out within a few seconds after the engine is started. - CORRECT ANSWER - true
Engine vacuum is being discussed. Technician A says that when the engine is operating under light loads,
engine vacuum is low. Technician B says that engine vacuum is high when the engine is operated under
heavy loads. Who is correct? - CORRECT ANSWER - neither
Which of the following is NOT an advantage of an electronic spark control system?
a.
It compensates for changes in engine (and sometimes outside air) temperature
b.
It allows lower compression ratio engines to be as efficient as higher compression ratio engines
c.
It makes changes many times faster than older (mechanical) systems
d.
It has a feedback mechanism which allows it to constantly compensate for changing conditions -
CORRECT ANSWER - b
The first decision the computer makes in determining the best operating strategy is to determine the
_____. - CORRECT ANSWER - engine operating mode
Catalytic converter monitors are being discussed. Technician A says that if the converter is working, the
downstream signal frequency should mirror the upstream sensor. Technician B says that the downstream
sensor should provide a low-frequency voltage signal. Who is correct? - CORRECT ANSWER - b
only
, Oxygen sensor monitors are being discussed. Technician A says the system monitors the sensor response
time as the system cycles lean-rich-lean. Technician B says that at certain times the monitor varies the
fuel delivery and checks for heated oxygen sensor response. Who is correct? - CORRECT
ANSWER - both a and b
EGR monitors are being discussed. Technician A says some EGR system monitors EGR flow by
measuring the difference in pressure as the EGR gas flows through an orifice (restriction). Technician B
says some EGR monitors measure the temperature of the EGR outlet to determine whether there is gas
flowing through the EGR valve. Who is correct? - CORRECT ANSWER - both a and b
Which of the following sensors is NOT used by the computerized ignition system to control ignition
timing? - CORRECT ANSWER - oxygen sensor
OBD II technology is being discussed. Technician A says the OBD II system has the ability to store a
freeze frame (snapshot) of the operating conditions that existed when the fault occurred. Technician B
says vehicle identification must be transmitted automatically to the scan tool. Who is correct? -
CORRECT ANSWER - both a and b
Mode 6 data show the results of the monitor diagnostic tests. - CORRECT ANSWER - true
The MAP sensor used on a turbocharged engine is calibrated the same as a MAP sensor for a
nonturbocharged engine. - CORRECT ANSWER - false
For most actuators, the circuit driver in the PCM applies a ground to the circuit to turn the actuator on and
removes the ground to turn the actuator off. - CORRECT ANSWER - true
Which of the following problems would NOT cause a oxygen sensor to appear bad?
a.
leaking fuel injector
b.
leaking intake manifold gasket
c.
leaking EGR valve
d.
ACTUAL Questions and CORRECT
Answers
Higher compression ratios tend to speed up combustion. - CORRECT ANSWER - true
The MIL light should illuminate when the ignition switch is turned to the run position [engine not
running] and go out within a few seconds after the engine is started. - CORRECT ANSWER - true
Engine vacuum is being discussed. Technician A says that when the engine is operating under light loads,
engine vacuum is low. Technician B says that engine vacuum is high when the engine is operated under
heavy loads. Who is correct? - CORRECT ANSWER - neither
Which of the following is NOT an advantage of an electronic spark control system?
a.
It compensates for changes in engine (and sometimes outside air) temperature
b.
It allows lower compression ratio engines to be as efficient as higher compression ratio engines
c.
It makes changes many times faster than older (mechanical) systems
d.
It has a feedback mechanism which allows it to constantly compensate for changing conditions -
CORRECT ANSWER - b
The first decision the computer makes in determining the best operating strategy is to determine the
_____. - CORRECT ANSWER - engine operating mode
Catalytic converter monitors are being discussed. Technician A says that if the converter is working, the
downstream signal frequency should mirror the upstream sensor. Technician B says that the downstream
sensor should provide a low-frequency voltage signal. Who is correct? - CORRECT ANSWER - b
only
, Oxygen sensor monitors are being discussed. Technician A says the system monitors the sensor response
time as the system cycles lean-rich-lean. Technician B says that at certain times the monitor varies the
fuel delivery and checks for heated oxygen sensor response. Who is correct? - CORRECT
ANSWER - both a and b
EGR monitors are being discussed. Technician A says some EGR system monitors EGR flow by
measuring the difference in pressure as the EGR gas flows through an orifice (restriction). Technician B
says some EGR monitors measure the temperature of the EGR outlet to determine whether there is gas
flowing through the EGR valve. Who is correct? - CORRECT ANSWER - both a and b
Which of the following sensors is NOT used by the computerized ignition system to control ignition
timing? - CORRECT ANSWER - oxygen sensor
OBD II technology is being discussed. Technician A says the OBD II system has the ability to store a
freeze frame (snapshot) of the operating conditions that existed when the fault occurred. Technician B
says vehicle identification must be transmitted automatically to the scan tool. Who is correct? -
CORRECT ANSWER - both a and b
Mode 6 data show the results of the monitor diagnostic tests. - CORRECT ANSWER - true
The MAP sensor used on a turbocharged engine is calibrated the same as a MAP sensor for a
nonturbocharged engine. - CORRECT ANSWER - false
For most actuators, the circuit driver in the PCM applies a ground to the circuit to turn the actuator on and
removes the ground to turn the actuator off. - CORRECT ANSWER - true
Which of the following problems would NOT cause a oxygen sensor to appear bad?
a.
leaking fuel injector
b.
leaking intake manifold gasket
c.
leaking EGR valve
d.
