engine performance ch 24-25

A conventional oxygen sensor needs to be heated to ________ degrees Fahrenheit before it can produce a usable signal.

750

Which of the following statements is NOT true? a. A conventional oxygen sensor has a minimum voltage of 0.000 volts and a maximum voltage of 1.000 volt. b. On a V-type engine, bank 1 is the side of the engine where cylinder #1 is located. c. An oxygen sensor measures the difference between the amount of oxygen inside the exhaust and the outside air. d. A conventional oxygen sensor receives a 5-volt reference voltage from the PCM.

A conventional oxygen sensor receives a 5-volt reference voltage from the PCM.

Besides the tailpipe, hydrocarbons (HC) can also be emitted from the _______. a. fuel tank b. hoses c. EVAP system d. All of the answers are correct.

All of the answers are correct.

Diagnostic trouble codes are being discussed. Technician A says a P0442 is a manufacturer's code and means different things, depending on what manufacturer built the car. Technician B says that a P0304 code is a universal code that means the same thing no matter what manufacturer built the car. Who is correct?

B only

A vehicle towed into the shop will crank but won't start. A quick check under the hood reveals that the spark plugs are not firing and the injectors are not receiving a pulse from the PCM. The technician notices that the MIL light does not come on when the key is turned to the run position. What should he do next?

Check the PCM's fuses, power wires, and ground wires

Which of the following is NOT an advantage of an electronic spark control system?

It allows lower compression ratio engines to be as efficient as higher compression ratio engines

Data collected by system sensors is stored in _____ memory.

RAM

Which of the following memory circuits is used to store trouble codes and other temporary information?

Random access memory

Which of the following statements is not true? a. DTCs that will not affect emissions will never illuminate the MIL. b. An active or current DTC represents a fault that was detected and occurred during two trips. c. When a two-trip fault is detected for the second time, a DTC is stored as a pending code. d. There are some DTCs that will set in one trip.

When a two-trip fault is detected for the second time, a DTC is stored as a pending code

A vehicle with a DTC for an engine coolant temperature out of range code is being tested.The serial data stream shows the coolant temperature to be 198 degrees Fahrenheit. When the technician tests the resistance between the ETC terminals, he finds infinite resistance. The specifications call for 20 to 40 ohms at 200 degrees Fahrenheit. After the ECT is replaced and the code is erased, the system runs normally and the code and MIL illumination do not reoccur. How is this possible?

When the ECT failed, the PCM substituted a nominal ECT value that allowed the engine to run in limp home mode; the substituted value was displayed by the scan tool

Two technicians are discussing OBD-II monitor readiness status. Technician A says that the vehicle must be driven through a drive cycle that includes several minutes of idle, low-speed cruise, medium-speed cruise, and deceleration before all monitors can be performed. Technician B says all monitors can be performed in five minutes of fast idling. Who is correct?

a only

An air/fuel ratio sensor is different from an oxygen sensor in that ______. a. the signal output is a varying current (amps) b. as the mixture becomes leaner, its output signal increases c. the output responds to minor changes in air/fuel mixture d. All the answers are correct.

all answers

Oxygen sensors may become contaminated by ______. a. coolant from blown head gaskets b. use of RTV silicone sealant in the intake system c. excessive oil consumption caused by worn rings. d. All the answers are correct.

all answers

The injector pulse width is the ______.

amount of time the injector opens and sprays fuel

Ignition spark typically occurs a few degrees _______.

before top dead center (BTDC)

Two technicians are discussing testing switch type sensors. Technician A uses an ohmmeter. Technician B uses a voltmeter. Who is correct?

both

Before performing any repairs on a vehicle with an illuminated MIL light: Technician A records all DTCs and freeze frame data. Technician B checks for service bulletins.Who is correct?

both A and B

Freeze frame data is being discussed. Technician A says erasing the code with a scan tool will erase the corresponding freeze frame data. Technician B says the freeze frame data is the sensor and output status data at the instant the DTC was set. Who is correct?

both A and B

The device that protects the PCM and other electronic components from the voltage spike created in the windings of a solenoid, relay, or magnetic clutch when they are turned off is called a ______.

clamping diode

A computer is capable of doing all of the following except___.

control the vehicle's operating conditions

Which sensor is used for misfire monitoring on OBD II systems?

crankshaft position sensor

In a GDI system (gasoline direct injection) the injector sprays fuel into the ______.

cylinders (combustion chamber)

The DLC connector on an OBDII vehicle is located under the______.

dash on the driver's side

An accelerator pedal position sensor (APP) is used on vehicles equipped with ______.

electronic throttle control

Which of the following jobs is NOT a function of the ignition system?

engaging the starter motor

An A/F ratio sensor can be tested in the same way as an oxygen sensor.

false

Higher-octane fuels are easier to ignite and burn faster than low-octane fuel.

false

The engine coolant temperature sensor is typically found in the radiator.

false

When there is a calibration update available for an OBD-II vehicle, the old EEPROM is removed from its socket in the PCM and a new EEPROM with the updated software is installed in its place.

false

The catalyst monitor test may fail for all of these reasons, except ___.

ignition system misfire

Which of the following tools should not be used to test an actuator unless the technician is directed to do so by the manufacturer's service procedures?

jumper wires

Which of the following problems would NOT cause a oxygen sensor to appear bad?

leaking muffler to tailpipe gasket

A technician connects a DMM with a MIN/MAX/AVG function to the output of an oxygen sensor. The engine is run at 2000 RPM for several minutes. During the test, the voltage toggles rapidly between 150 and 900 millivolts. At the end of the test, the MAX voltage was .967 V, the MIN voltage was .087 V, and the AVG voltage was .683 V. Technician A says the sensor is faulty and should be replaced. Technician B says there could be a vacuum leak that caused the sensor voltage to have a higher than normal average. Who is correct?

neither

Which of the following chemicals is NOT a pollutant?

nitrogen (N2)

Which of the following sensors is NOT used by the computerized ignition system to control ignition timing?

oxygen sensor

Which of the following tools is NOT used in testing engine sensors?

test light

A bad ground can cause an increase in the reference voltage to a sensor.

true

Because air/fuel ratio sensors produce a signal only after their current output has been processed by the PCM, they cannot be tested with a voltmeter or lab scope.

true

Higher compression ratios tend to speed up combustion.

true

Mode 6 data show the results of the monitor diagnostic tests.

true

OBD-II regulations require all vehicle manufacturers to use the same names and acronyms for all electric and electronic systems related to the engine and emission control systems.

true

Port fuel injection systems have a throttle plate assembly, but fuel never passes by the plate.

true

The PCM can be electronically linked to other control modules.

true

The PCM can turn off the A/C compressor when the engine is operating at full throttle.

true