Chapter 75

Which type of sensor uses a burn-off circuit?

A.) Hot wire MAF sensor

Two technicians are diagnosing a poorly running engine with no stored DTC's. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means the MAF sensor is supplying incorrect air flow information to the PCM. Technician B says that this indicates the PCM is defective. Who is right?

A.) Technician A

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

A.)Mass Air Flow sensor

Technician A says that a MAF sensor is a high-authority sensor and responsible for determining the fuel of the engine based on the measured amount of air entering the engine. Technician B says that a cold wire MAF sensor uses the electronics in the sensor itself to heat a wire 20°C below the temperature of the air entering the engine. Who is right?

A.)Technician A

Which of these can be used to measure the frequency (Hz) output of the sensor and compare the reading with specifications?

B.) DMM (digital multimeter)

A fuel injection system that does not use a sensor to measure the amount (or mass) of air entering the engine is usually called a ___________ type of system

B.) Speed Density

A P0103 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that a defective MAF sensor could be the cause. Who is right?

B.)Technician B

A P0102 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that an open sensor voltage supply circuit could be the cause. Who is right?

C.) Both technicians

The MAF sensor on a General Motors 3800 V-6 is being tested for contamination. Technician A says that the sensor should show over 100 grams per second on a scan tool display when the accelerator is depressed to WOT (wide open throttle) on a running engine. Technician B says that the output frequency should exceed 7000 Hz when the accelerator pedal is depressed to WOT on a running engine. Who is right?

C.) Both technicians

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

C.) Either A or B A.)Poor running in a forward gear but OK i. reverse B.)Allow false air into the engine

Air that enters the engine without passing through the air flow sensor is called________.

C.) False air

A contaminated sensing wire in a MAF sensor will cause the fuel system to _________ at idle.

C.) go rich

Technician A says that a MAF sensor actually measures the density and amount of air flowing into the engine. Technician B says a that hot wire MAF uses the electronics in the sensor itself to heat a wire 70°C above the temperature of the air entering the engine. Who is right?

C.)Both technicians

The typical MAF reading on a scan tool with the engine at idle speed and normal operating temperature is ______________.

D.) 3 to 7 grams per second

A vehicle runs fine when in reverse yet has a rough idle and stalling when put in drive. This could be caused by ____________.

D.) A cracked air inlet hose

Which airflow sensor has a dampening chamber?

D.) A vane airflow sensor

Two technicians are discussing Karman Vortex sensors. Technician A says that they contain a burn-off circuit to keep them clean. Technician B says that they contain a movable vane. Which technician is correct?

D.) Neither technician A nor technician B

MAF sensor electrical connectors should be checked for all of these, EXCEPT___________.

D.) Over-tight connectors

Which sensor has a switch that controls the electric fuel pump?

D.) VAF

What are the two methods of sensing incoming engine air flow?

D.)Speed density and mass air flow