A technician suspects that the exhaust gas recirculation (EGR) valve is closed. Which of the following would indicate a closed EGR valve?
A) Spark knock
B) Stalling
C) Rough idle
D) Engine surge
Answer (2)
A closed EGR valve can lead to symptoms such as spark knock, which is an indication of unwanted combustion in the engine. While stalling, rough idle, and engine surge can occur due to various issues, spark knock is most closely associated with a malfunctioning EGR valve. This is due to increased combustion temperatures resulting from the lack of exhaust gas recirculation. ;
The most significant indication of a closed EGR valve is spark knock, which occurs due to increased combustion temperatures from the absence of exhaust gas recirculation. While other symptoms like stalling and rough idle can occur for various reasons, spark knock is directly linked to the EGR valve's malfunction. Therefore, option A) Spark knock is the best choice.
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