单项选择题
A.restricted turbocharger air intake
B.oil leak into the turbocharger
C.dribbling injector
D.low fuel viscosity
单项选择题 The exhaust valve opens before bottom dead center in a four stroke engine to（） Ⅰ.allow for blow down Ⅱ.Reduce pumping losses
单项选择题 Which of the turbo-charging systems listed operates with the least average back pressure in the exhaust manifold?（）
单项选择题 Which of the following conditions indicates the dilution of diesel engine lube oil by fuel oil?（）