Technician A says if the EGR valve does not open, the engine may emit excessive amounts of HC. Technician B says if the EGR valve does not open, the engine may detonate on acceleration. Who is correct?
A)A only
B)B only
C)both A and B
D)neither A nor B

Question

Quizplus · Accepted Answer

Technician B is correct because if the EGR (Exhaust Gas Recirculation) valve does not open, it can lead to increased combustion temperatures, which in turn can cause engine detonation or "knocking" during acceleration. The EGR valve's purpose is to recirculate a portion of the exhaust gases back into the combustion chamber to cool the combustion temperature, thereby reducing NOx emissions and preventing detonation. Technician A's statement about excessive HC (hydrocarbons) emissions is incorrect in this context; HC emissions are more directly related to incomplete combustion or issues with the ignition system, not the operation of the EGR valve.

Technician a Says If the EGR Valve Does Not Open