Deck 17: Map and Maf Sensors

Question 1

The MAP sensor is used when the OBD-II does a test of the ________ system.

A) feedback
B) timing
C) EGR
D) cooling

Answer 1

C

Question 2

As the altitude of the vehicle increases, barometric pressure ________.

A) decreases
B) does not change
C) increases
D) None of the above

Answer 2

A

Question 3

Which of these tools could be used to test a MAP sensor?

A) Scan tool
B) Digital voltmeter
C) Hand-operated vacuum pump
D) Any of the above

Answer 3

D

Question 4

If the MAF sensor fails, the PCM uses ________ to calculate fuel delivery needs.

A) throttle position and transmission RPM
B) RPM and throttle position
C) MAP and throttle position
D) RPM alone

Question 5

An eight-wire mas airflow sensor senses all of these EXCEPT ________.

A) RPM
B) humidity
C) intake air temperature
D) airflow

Question 6

Which of these can be used to measure the frequency (Hz) output of the MAF sensor?

A) Logic Probe
B) Megohmmeter
C) High impedance test light
D) DMM (digital multimeter)

Question 7

Technician A says that pressure below atmospheric pressure is called vacuum and is measured in inches of Mercury (Hg). Technician B says that a manifold absolute pressure (MAP) sensor uses a low vacuum in the sensor to determine the pressure. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 8

The MAF sensor is used mostly to determine the amount of ________ to deliver to the engine.

A) idle air
B) vacuum correction
C) spark advance
D) fuel

Question 9

Technician A says that a MAF sensor actually measures the density and amount of air flowing into the engine, which results in accurate engine control. Technician B says that a hot wire MAF sensor uses the electronics in the sensor itself to heat a wire 70°C above the temperature of the air entering the engine. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 10

A MAP sensor is being tested. Technician A says that many MAP sensors also act as a barometric pressure sensor when the ignition switch is first turned on. Technician B says on many MAP sensors the signal voltage should increase when the vacuum at the sensor decreases. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 11

Technician A says that a heavy engine load results in high intake manifold vacuum and a high MAP sensor signal voltage. Technician B says that a MAP sensor uses a perfect vacuum (zero absolute pressure) in the sensor to determine the pressure. Which technician is correct?

A) Technician A only
B) Technician B only
C) Both technicians A and B
D) Neither technician A nor B

Question 12

When testing a MAP sensor that produces an analog voltage signal with 18 in. hg. applied to the sensor, the sensor signal is l.4 volts. When 13 in. hg. is supplied to the sensor, the sensor signal should be which of these voltage values?

A) 2.3
B) 2.6
C) 1.4
D) 1.6

Question 13

Most MAP sensors produce what type of output signal?

A) DC milliamperes (DCA)
B) Analog DC voltage (DCV)
C) AC voltage (ACV)
D) Frequency (Hz)

Question 14

The output of a MAP sensor is reading 1.0 volt. What is the approximate engine vacuum in inches of Mercury (Hg)?

A) 17-21
B) 10-15
C) 0
D) 5

Question 15

A scan tool can be used to test a MAP sensor by monitoring the injector pulse width (in milliseconds) when ________ is being applied to the MAP sensor.

A) ground
B) vacuum
C) air pressure
D) voltage

Question 16

The opening of the EGR valve pintle does NOT cause a change in the MAP sensor reading. This could cause ________.

A) an EGR flow rate DTC to set
B) the transmission to downshift
C) a high idle speed
D) the engine to stall

Question 17

Dirt can affect all of these sensors, EXCEPT ________.

A) low frequency (older style) MAF
B) hot wire MAF (mass air flow sensor)
C) cold wire MAF (mass air flow sensor)
D) high frequency (new style) MAF

Question 18

Which of the following components measures the volume and density of the incoming air?

A) Mass Airflow Sensor
B) Oxygen Sensor
C) Throttle Position Sensor
D) Manifold Absolute Pressure Sensor

Question 19

The component shown (shaded) has a crack or split in it. What would this cause?

A) Allow false air into the engine
B) Poor running in a forward gear but OK in reverse
C) Either A or B
D) Neither A nor B