Engine Performance Final Questions
and Answers with Verified Solutions
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? ✔✔d.
neither A nor B
Ignition spark typically occurs a few degrees _______. ✔✔a. before top dead center (BTDC)
Which of the following is NOT an advantage of an electronic spark control system? ✔✔b. It
allows lower compression ratio engines to be as efficient as higher compression ratio engines
Air/fuel ratios are being discussed. Technician A says that when the air fuel ratio is higher than
14.7 to 1 the engine produces more power. Technician B says that when the air fuel ratio is lower
than 14.7 to 1 the engine uses less fuel. Who is correct? ✔✔d. neither A nor B
The first decision the computer makes in determining the best operating strategy is to determine
the _____. ✔✔b. 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?
✔✔b. B only
What sensor is used to detect engine misfire? ✔✔a. crankshaft position
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?
✔✔c. 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? ✔✔c. both A and B
Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will
erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor
and output status data at the instant the DTC was set. Who is correct? ✔✔c. both A and B
,To read flash codes on an OBD I Chrysler-built vehicle, you must ______. ✔✔d. turn the
ignition key on and off three times in five seconds, ending with on
Which of the following sensors is NOT used by the computerized ignition system to control
ignition timing? ✔✔a. 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? ✔✔c. Both A and B
Which of the following does NOT use a magnetic pulse generator [PM generator]? ✔✔b. throttle
position sensor
The engine coolant temperature sensor helps to control all the following EXCEPT: ✔✔a. fuel
pressure
, Technician A tests an MAF sensor with a scan tool by watching for erratic changes in flow while
the engine idles. Technician B checks an MAF sensor by tapping it lightly with the handle of a
screwdriver while watching the waveform on a lab scope. Who is correct? ✔✔c. both A and B
A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can
produce a usable signal. ✔✔b. 750
Which of the following problems would NOT cause a oxygen sensor to appear bad? ✔✔d.
leaking muffler to tailpipe gasket
Which of the following tools cannot be used to test an oxygen sensor? ✔✔b. analog voltmeter
A throttle position sensor has ______. ✔✔a. a 5-volt reference input terminal
An accelerator pedal position sensor (APP) is used on vehicles equipped with ______. ✔✔a.
electronic throttle control
Which of the following is NOT an actuator? ✔✔a. PCV valve
and Answers with Verified Solutions
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? ✔✔d.
neither A nor B
Ignition spark typically occurs a few degrees _______. ✔✔a. before top dead center (BTDC)
Which of the following is NOT an advantage of an electronic spark control system? ✔✔b. It
allows lower compression ratio engines to be as efficient as higher compression ratio engines
Air/fuel ratios are being discussed. Technician A says that when the air fuel ratio is higher than
14.7 to 1 the engine produces more power. Technician B says that when the air fuel ratio is lower
than 14.7 to 1 the engine uses less fuel. Who is correct? ✔✔d. neither A nor B
The first decision the computer makes in determining the best operating strategy is to determine
the _____. ✔✔b. 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?
✔✔b. B only
What sensor is used to detect engine misfire? ✔✔a. crankshaft position
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?
✔✔c. 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? ✔✔c. both A and B
Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will
erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor
and output status data at the instant the DTC was set. Who is correct? ✔✔c. both A and B
,To read flash codes on an OBD I Chrysler-built vehicle, you must ______. ✔✔d. turn the
ignition key on and off three times in five seconds, ending with on
Which of the following sensors is NOT used by the computerized ignition system to control
ignition timing? ✔✔a. 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? ✔✔c. Both A and B
Which of the following does NOT use a magnetic pulse generator [PM generator]? ✔✔b. throttle
position sensor
The engine coolant temperature sensor helps to control all the following EXCEPT: ✔✔a. fuel
pressure
, Technician A tests an MAF sensor with a scan tool by watching for erratic changes in flow while
the engine idles. Technician B checks an MAF sensor by tapping it lightly with the handle of a
screwdriver while watching the waveform on a lab scope. Who is correct? ✔✔c. both A and B
A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can
produce a usable signal. ✔✔b. 750
Which of the following problems would NOT cause a oxygen sensor to appear bad? ✔✔d.
leaking muffler to tailpipe gasket
Which of the following tools cannot be used to test an oxygen sensor? ✔✔b. analog voltmeter
A throttle position sensor has ______. ✔✔a. a 5-volt reference input terminal
An accelerator pedal position sensor (APP) is used on vehicles equipped with ______. ✔✔a.
electronic throttle control
Which of the following is NOT an actuator? ✔✔a. PCV valve
