Exam 33: Emission Control Systems

OBD-II canister purge systems are being discussed. Technician A says the canister purge solenoid valve is only open and controlled when the system is in open loop. Technician B says because the system responds to current engine and operating conditions, the purging of the vapors does not affect drivability. Who is correct?

What is the cause of photochemical smog?

A ____________________type EGR valve has three electric solenoids. Each of the solenoids and orifices has a different size. The rate of flow is based on the combination of solenoids turned on by the PCM.

HC and NO _X emissions exposed to sunlight in stagnant air produce ____________________.

All the following are considered harmful gases EXCEPT:

Carbon dioxide (CO₂)is a greenhouse gas and may be the major cause of global warming.

The AIR system reduces ______.

During the OBD-II EVAP purge monitor, the duty cycle applied to the purge solenoid is increased. The PCM should see a change in ____________________.

The exhaust gas recirculation system reduces ______.

The ____________________ system removes blowby gases from the crankcase and recirculates them to the engine intake.

A linear EGR valve contains up to three electric solenoids that are operated directly by the PCM.

What is an I/M 240 test?

NO _X emissions increase as combustion temperatures increase.

Technician A says the back pressure transducer may be incorporated into the design of the EGR valve. Technician B says negative back pressure transducers use the vacuum in the exhaust between pressure pulses to modulate the EGR flow. Who is correct?