Technician A says that a vacuum leak can cause a rough idle or stalling. Technician B says that spark knock (ping or detonation) is often caused by a too rich air-fuel mixture or an excessively low engine operating temperature. Which technician is correct?

Question

Quizplus · Accepted Answer

Technician A is correct because a vacuum leak can indeed cause a rough idle or stalling due to unmeasured air entering the engine, leading to an incorrect air-fuel mixture. Technician B is incorrect because spark knock is typically caused by a too lean air-fuel mixture, excessive engine load, or high temperatures, not a too rich mixture or low engine temperature.

Technician a Says That a Vacuum Leak Can Cause a Rough