CDX Diesel chpt33
Dosing the exhaust system of a 2007 diesel engine with fuel is necessary to do which of the following?
Actively regenerate a catalyzed DPF.
Technician A says nitric oxide is used by the DPF to convert soot to harmless emissions. Technician B says that the SCR catalysts cause nitric oxide to convert to harmless emissions. Who is correct?
Both Tech A/B
Technician A says that DEF is always evacuated from lines and valves after the vehicle has shut down to prevent DEF from crystalizing and plugging the SCR system. Technician B says that DEF is removed to prevent it from freezing and causing damage. Who is correct?
Both Technician A and Technician B
Which strategy will most likely be used to passively regenerate a catalyzed DPF?
Driving at speeds above 45 mph (72 km/h) for a minimum of 20 minutes
The use of SCR delivers which of the following?
Improved fuel economy and fewer DPF regenerations because injection timing is advanced
Which of the following is the function of an intake throttle valve on a diesel engine equipped with a DPF?
Increase exhaust temperature
Catalyzed DPFs require oil with which of the following qualities?
Low ash content
A slip catalyst converts:
NH3 to N2.
Technician A recommends a yearly removal and cleaning of the DPF to customers. Technician B says the DPF needs to be actively regenerated at every oil change. Who is correct?
Neither
Which process is used to clean ash from a DPF?
Removal and back-flushing with compressed air
The DPF warning light is flashing along with the red shut-down warning lamp. Technician A says the DPF filter needs to be removed and replaced. Technician B says the DPF needs an active regeneration. Who is correct?
Tech A
Technician A says diesel exhaust oxidation catalysts used by diesel engines are like those used in automobiles for the last two decades. Technician B says diesel exhaust oxidation catalysts must store noxious emissions in the substrate when the exhaust temperatures are low. Who is correct?
Tech B
Technician A says the problem with using automobile catalysts in the exhaust system of diesel engines is diesel engine exhaust's excess air and cool temperatures. Technician B says diesel exhaust catalysts need to be designed to withstand the higher exhaust temperatures of a diesel engine and its exhaust's lower oxygen content. Who is correct?
Tech B
Technician A says that lean NOx traps are used by only light-duty diesel engines. Technician B says that lean NOx traps are used by light- and heavy-duty diesel engines. Who is correct?
Tech a
After examining a broken and disintegrated DPF filter, Technician A says the filter damage was caused by water contamination. Technician B says the filter was damaged by too frequent back-to-back regenerations. Who is correct?
Technician B
Technician A says that, without the Delta P sensor, the exhaust DPF would not regenerate because the amount of soot loading could not be properly calculated. Technician B says that the amount of soot loading is only calculated, and not measured, using the Delta P sensor. Who is correct?
Technician B
The use of SCR and DPFs requires which type of fuel?
Ultra-low-sulfur diesel fuel (ULSD) with fewer than 15 ppm sulfur
Which process is used to clean ash from a DPF?
Which process is used to clean ash from a DPF?
