Engine noise is the sound made by an engine, usually from a car or other motorized vehicle. The crossword solutions for engine noise are PURR (4 letters), KNOCK (5 letters), vroom (5 letters), PING (4 letters), CHUG (4 letters), and HUM (3 letters). PURR is a low, continuous sound made by a motor running smoothly. KNOCK is a loud, irregular sound made by a motor that is not running properly. Vroom is a loud, high-pitched sound made by a motor running at full speed. PING is a sharp, metallic sound made by a motor when it is running. CHUG is a slow, rhythmic sound made by a motor running at low speed. HUM is a low, steady sound made by a motor running at a constant speed.