The longer the ignition delay period occurs in a diesel engine, the （）.

单项选择题Poor combustion in a diesel engine can be caused by （）.

A.high compression pressure
B.low intake air temperature
C.low exhaust pressure
D.high scavenge air pressure

单项选择题High firing pressures and a low exhaust temperature in a diesel engine may result from （）.

A.decreased piston to cylinder head clearance
B.increased exhaust system back pressure
C.early fuel injection timing
D.low scavenge air temperature

单项选择题Whether using a centrifuge or a simple filter, oil cleaning and filtration will be the most effective when the oil is at a （）.

A.high temperature and a high viscosity
B.high temperature and a low viscosity
C.low temperature and a high viscosity
D.low temperature and a low viscosity

单项选择题Exhaust valve grooving and corrosion is caused by certain components of residual fuel oilThese components are sodium, sulfur, and （）.

A.vanadium
B.carbon
C.copper
D.ash

单项选择题Which of the following problems may occur if the opening pressure of a fuel injection nozzle is greater than specified by the engine manufacturer?（）

A.The amount of fuel injected will be increased
B.The start of injection will be retarded
C.The nozzle will permit fuel to dribble
D.The spray pattern will be distorted