Ch 52 Automotive Study Tool

An OBD II drive cycle is being performed on a vehicle, but has to be interrupted. Technician A says that the cycle can be started again immediately. Technician B says that the cycle cannot be started again until engine coolant temperature drops low enough for the ECM to start in the open loop mode. Who is right?

• A only

• B only

• Both A and B

• Neither A nor B

Catalytic converters are a burn hazard to technicians, since they can reach an operating temperature as high as ____°F.

• 2100A

• 1400B

• 750C

• 1800D

The term stoichiometric indicates that a fuel mixture is ____.

• contaminated

• too rich

• chemically correct

• too lean

Which of the following gases are measured by a two-gas exhaust analyzer?

• Hydrocarbons and carbon monoxide.A

• Carbon dioxide and oxides of nitrogen.B

• Carbon monoxide and oxygen.C

• Oxygen and hydrocarbons.D

A high carbon monoxide reading from an exhaust analyzer indicates that ____.

• the air injection is malfunctioning

• there is an incomplete burning of fuel

• ignition timing is too far advanced

• Any of the above.

Which of the following problems can be caused by an EGR valve that is stuck open?

• Detonation.

• Pinging.

• Poor fuel economy.

• Rough idle.

Technician A says that oxides of nitrogen can be measured with a four-gas exhaust analyzer. Technician B says that oxides of nitrogen can be measured only by using a five-gas analyzer. Who is right?

• A only.

• B only.

• Both A and B

• Neither A nor B

Typically, if the levels of CO exceed the O2 levels, the air-fuel mixture is ____.

• lean

• rich

• stoichiometric

• None of the above.

Oxides of nitrogen can be measured by a three-gas analyzer.

• True

• False

Higher-than-normal hydrocarbon readings can be caused by improper ignition timing.

• True

• False