Emissions UPDATED Exam Questions and
CORECT Answers
short-term and long-term fuel trim readings are being discussed. tech a says a scale of 0 to 255 is
used. tech b says percentage is used. - CORRECT ANSWER tech b
a vehicle is being diagnosed with a low fuel pressure problem. A fuel pump current test reveals
higher than normal current flow. tech a says the vehicle may have a clogged fuel filter. tech b
says the fuel pump ground wire may be loose or corroded. - CORRECT ANSWER tech a
only because if a electric pump does not have a good ground or good power then it will not work
aka a no fuel pressure problem
quick tests to a GM hot film mass airflow meter on an engine with idling problems are being
performed. tech a taps on the meter with a plastic mallet. tech b unplugs the meter. - CORRECT
ANSWER both
tech a says throttle body cleaner may be used to clean the IAC motor internal components. tech b
says on some vehicles, IAC motor damage can occur if the pintle is cleaned with throttle body
cleaner. - CORRECT ANSWER neither
vacuum leaks in speed density systems can be verified by watching the ___ on a scan tool. -
CORRECT ANSWER O2s Sensor cross
All current fuel tank filler tubes have a built-in restrictor that prevents the entry of the larger
leaded fuel delivery nozzle at gas pumps. - CORRECT ANSWER true
All quick-disconnect fuel line fittings are hand releasable and do not require special tools to
disconnect. - CORRECT ANSWER false
All modern vehicles use a threaded, removable gas cap. - CORRECT ANSWER false
, GDI [gasoline direct injection] systems allow engines to run at very lean air/fuel ratios and
eliminate the need for EGR systems. - CORRECT ANSWER false
Fuel trim can be monitored for diagnostic purposes. - CORRECT ANSWER true
Fuel tanks may be constructed of all the following EXCEPT:
aluminum
steel
plastic
brass - CORRECT ANSWER brass
Technician A says the gas cap is equipped with a pressure release valve that opens if there is
excess vapor pressure in the fuel tank. This prevents tank ballooning. Technician B says the gas
cap is equipped with a vacuum relief valve that opens if there is an excessive amount of vacuum
in the fuel tank. This prevents tank collapse. Who is correct? - CORRECT ANSWER both
Which of the following is NOT a component of a throttle-by-wire system?
accelerator pedal position sensor
throttle position sensor
throttle control motor
IAC motor [idle air control] - CORRECT ANSWER IAC motor [idle air control]
CORECT Answers
short-term and long-term fuel trim readings are being discussed. tech a says a scale of 0 to 255 is
used. tech b says percentage is used. - CORRECT ANSWER tech b
a vehicle is being diagnosed with a low fuel pressure problem. A fuel pump current test reveals
higher than normal current flow. tech a says the vehicle may have a clogged fuel filter. tech b
says the fuel pump ground wire may be loose or corroded. - CORRECT ANSWER tech a
only because if a electric pump does not have a good ground or good power then it will not work
aka a no fuel pressure problem
quick tests to a GM hot film mass airflow meter on an engine with idling problems are being
performed. tech a taps on the meter with a plastic mallet. tech b unplugs the meter. - CORRECT
ANSWER both
tech a says throttle body cleaner may be used to clean the IAC motor internal components. tech b
says on some vehicles, IAC motor damage can occur if the pintle is cleaned with throttle body
cleaner. - CORRECT ANSWER neither
vacuum leaks in speed density systems can be verified by watching the ___ on a scan tool. -
CORRECT ANSWER O2s Sensor cross
All current fuel tank filler tubes have a built-in restrictor that prevents the entry of the larger
leaded fuel delivery nozzle at gas pumps. - CORRECT ANSWER true
All quick-disconnect fuel line fittings are hand releasable and do not require special tools to
disconnect. - CORRECT ANSWER false
All modern vehicles use a threaded, removable gas cap. - CORRECT ANSWER false
, GDI [gasoline direct injection] systems allow engines to run at very lean air/fuel ratios and
eliminate the need for EGR systems. - CORRECT ANSWER false
Fuel trim can be monitored for diagnostic purposes. - CORRECT ANSWER true
Fuel tanks may be constructed of all the following EXCEPT:
aluminum
steel
plastic
brass - CORRECT ANSWER brass
Technician A says the gas cap is equipped with a pressure release valve that opens if there is
excess vapor pressure in the fuel tank. This prevents tank ballooning. Technician B says the gas
cap is equipped with a vacuum relief valve that opens if there is an excessive amount of vacuum
in the fuel tank. This prevents tank collapse. Who is correct? - CORRECT ANSWER both
Which of the following is NOT a component of a throttle-by-wire system?
accelerator pedal position sensor
throttle position sensor
throttle control motor
IAC motor [idle air control] - CORRECT ANSWER IAC motor [idle air control]
