DSL-202 Chapter 30 Variable Geometry and Series Turbochargers

Exhaust gas backpressure can reach __________ to overcome intake air pressure.

• 60 psi

• 
  80 n/m

• 80 psi

• 70 psi

Which of the following statements is correct about variable geometry turbochargers?

• A VGT turbocharger is capable of changing boost pressure independently of engine speed and load.

• A VGT turbocharger is capable of changing boost pressure independently of only engine speed

• Both A and B

• Neither A nor B

Technician A says that the primary purpose of using VGTs is to provide maximum boost pressure. Technician B says that the primary purpose of using VGTs has to do with the operation of exhaust gas recirculation (EGR) systems. Who is correct?

• Technician A

• Technician B

• Both Technician A and Technician B

• Neither Technician A nor Technician B

The primary purpose for using VGTs has to do with the operation of ___________________systems.

• Exhaust gas recirculation (EGR)

• Intercooler (IC)

• Intercooler (IC)

• Hydraulic electronic unit injector (HEUI) 

In diesel engines with EGR systems up to _____ of the intake charge can be exhaust gas.

• 40%

• 50%

• 60%

• 30%

Which of the following statements is correct with regard to the turbo speed sensor?

• If overspeed is detected, the ECM will open the vanes in the VGT to slow turbine speed.

• The HD-ODB system monitors the turbo operation using the speed sensor

• Both A and B

• Neither A nor B

Technician A says that if overspeed is detected, the ECM will close the vanes in a VGT to slow the turbine. Technician B says that a turbo speed sensor is the equivalent of a wastegate on a turbocharger. Who is correct?

• Technician A

• Technician B

• Both Technician A and Technician B

• Neither Technician A nor Technician B

Technician A says closing the nozzle to narrow its width decreases turbine speed and boost pressure as exhaust backpressure drops. Technician B says that closing the nozzle to narrow its width rapidly increases turbine speed and boost pressure as exhaust backpressure rises. Who is correct?

• 
  Technician A

• Technician B

• Both Technician A and Technician B

• Neither Technician A nor Technician B

The nozzle ring actuation is controlled by __________.

• The ECM

• The intake sensing hose

• A spool valve

• Exhaust energy/pressure

EGR gas flow does not need to accompany __________.

• Low load conditions

• Low boost pressure conditions

• High boost pressure conditions

• None of these is correct.