CEI Evaporative Emission Control Systems 2

Question 1

During a smoke machine test of an EVAP system, where is the smoke typically introduced?

Accepted Answer

Into the EVAP service port or vent solenoid port

Answer

Into the intake manifold vacuum port

Answer

Into the exhaust pipe upstream of the catalytic converter

Answer

Into the PCV valve inlet hose

Question 2

What is the function of the canister vent valve (vent solenoid) in an EVAP system?

Accepted Answer

It opens to allow fresh air into the canister during purge and closes during leak tests

Answer

It prevents fuel liquid from entering the charcoal canister

Answer

It regulates canister temperature to improve adsorption

Answer

It opens the fuel filler neck vent during refueling

Question 3

A P0446 diagnostic trouble code is most associated with which EVAP system component?

Accepted Answer

Canister vent control valve circuit

Answer

Purge flow solenoid valve

Answer

Fuel tank pressure sensor

Answer

Fuel cap sealing ring

Question 4

What constitutes a 'gross leak' in OBD II EVAP system terminology?

Accepted Answer

A leak equal to or larger than approximately 0.080-inch orifice equivalent

Answer

Any leak smaller than a 0.010-inch orifice equivalent

Answer

Vapors leaking past the purge valve into the intake at idle

Answer

A cracked charcoal canister body

Question 5

Which of the following BEST describes a non-intrusive OBD II EVAP test?

Accepted Answer

The PCM commands tests using natural driving conditions without external equipment

Answer

A technician manually pressurizes the fuel tank with nitrogen

Answer

A smoke machine is connected to the EVAP service port

Answer

The fuel cap is removed and replaced to verify its seal

Question 6

What effect does a saturated (fuel-soaked) charcoal canister have on vehicle emissions?

Accepted Answer

It causes excessive hydrocarbon emissions and can damage the purge valve or engine

Answer

It reduces NOx emissions by absorbing combustion byproducts

Answer

It improves fuel economy by returning liquid fuel to the tank

Answer

It has no measurable effect on tailpipe emissions

Question 7

Which driving cycle condition is most likely to allow an EVAP large leak monitor to complete?

Accepted Answer

Cold start followed by a warm-up period with moderate city driving

Answer

Sustained highway driving above 70 mph

Answer

Aggressive acceleration from a stop repeated multiple times

Answer

Idling for 20 or more minutes in park