Diesel CDX chat. 31
What is the purpose of a mass air flow (MAF) sensor on an EGR-equipped engine?
To adjust air fuel ratios on OBDII compliant vehicles
What is the mechanism used by internal EGR systems to introduce EGR gas into cylinders?
An EGR valve located between the exhaust and intake manifold
Technician A says the piston stroke length in an EGR engine is often longer than in the same model engine without an EGR system. Technician B says that the longer stroke length used by some EGR model engines has nothing to do with the use of EGR, and that some EGR engines have shorter stroke length than non-EGR model engines. Who is correct? Group of answer choices
Both Tech A and B
Under which of the following conditions is EGR typically disabled?
Excessively high engine coolant temperatures
Which combination of combustion conditions produces the highest NOXemissions from diesel engines?
High cylinder temperatures and pressures
Technician A says that EGR systems lower in-cylinder NOX formation by reducing peak cylinder pressures and temperatures. Technician B says EGR systems reduce NOX emissions by reducing displaced air in the cylinder. Who is correct?
Tech A
Which of the following environmental problems is caused primarily by NOXemissions?
Photochemical smog
Technician A says that EGR systems lower in-cylinder NOX formation by reducing peak cylinder pressures and temperatures. Technician B says EGR systems reduce NOX emissions by reducing displaced air in the cylinder. Who is correct? Group of answer choices
Tech A
Technician A says that oxygen sensors used by diesel engines adjust air-fuel ratios. Technician B says that oxygen sensors can be used to adjust the amount of EGR gas metered into the cylinders. Who is correct?
Tech A
Technician A says that EGR gas containing soot is present in all EGR systems. Technician B says that Caterpillar's EGR system, called the Clean Gas Induction system, does not contain soot. Who is correct?
Tech B
Technician A says that diesel engines use MAF sensors to measure exhaust airflow into the cylinders. Technician B says that exhaust gas does not pass through an MAF sensor so the MAF sensors cannot measure exhaust gas flow. Who is correct?
Tech B
Technician A says that internal EGR systems use a throttle plate to draw EGR gases into the air intake flow. Technician B says that high-pressure cooled EGR systems need throttle plates to draw exhaust gases into the intake manifold. Who is correct?
Tech B
Technician A says that turbocharger boost pressures are higher in EGR engines to compensate for power loss when using EGR gas. Technician B says that higher boost pressures are used to ensure the combustion chamber receives an adequate amount of oxygen to support combustion. Who is correct?
Tech B
What happens to the mass of intake airflow into an engine when the EGR is enabled?
The mass decreases.
