Exam 34: Emission Control Diagnosis and Service

All EGR valves can be tested with a vacuum gauge while the engine is idling.

Technician A says a loose oil filler cap or a dip stick that is not fully seated in the dipstick tube can change the LTFT on a MAF system. Technician B says the PCV system will draw unfiltered air through these leaks which could result in premature wear of engine parts. Who is correct?

In an engine in good condition running at 2,000 rpm, with a working EGR system, NO _X should be below _____ ppm.

Technician A says the AIRB valve directs secondary air either to the intake manifold or to the catalytic converter. Technician B says with the engine at normal operating temperature, the AIR system sometimes goes back into upstream mode with the engine idling. Who is correct?

A rich air fuel mixture will cause high ____________________ emissions.

What should you do if a vehicle has a gas odor?

The OBD-II EGR system monitor tests the functioning of the EGR system by opening the EGR valve while monitoring the change in ______.

What tool is needed to test a digital EGR valve?

Starting with the 2000 model year, the new EVAP monitor system is designed to detect leaks as small as ___________________ inch.

A water manometer for testing crankcase pressure/vacuum can be made from a 2 foot length of _____________________.

Technician A says cylinder misfiring causes a significant increase in HC emissions. Technician B says a dirty air filter may cause high CO emissions. Who is correct?

If the engine stalls at idle when the EGR is fully opened, the EGR system can be assumed to be working at peak efficiency.

When the engine is running at peak efficiency, the only gas that is desirable to be at its peak level is ______.

A dirty air filter may cause lower than normal ___________________ emissions.

What happens if a PCV valve is stuck in the open position?

Identify the two causes of lower than normal CO₂ emissions.

Excessively high CO emissions may be caused by a ______.

A scan tool can be used to diagnose a faulty ______.

To monitor the vapor purge in most systems, the PCM changes the duty cycle of the purge solenoid while monitoring the ______.

An alternative to the I/M 240 test is the acceleration simulation mode (ASM)test.