Technician A says timing-chain stretch can retard valve timing and set a camshaft/crankshaft correlation code. Technician B says a stretched timing chain has no effect on engine performance. Who is correct?

解析

A stretched or worn timing chain changes the relationship between crankshaft and camshaft position, retarding valve timing and often setting a correlation DTC. This can cause rough running and reduced power. Technician B is incorrect because timing is directly affected.