单选题Excessive diesel engine back pressure may be an indication of （）Acarbon buildup in the exhaust manifoldBovercooling of the exhaust manifoldCeroded muffler baffle platesDhigh injection pressure
单选题
Excessive diesel engine back pressure may be an indication of （）
A
carbon buildup in the exhaust manifold
B
overcooling of the exhaust manifold
C
eroded muffler baffle plates
D
high injection pressure
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