Knock when warmed up...

[yaris4eva]

Hi guys i have began noticing a faint knocking when my car is fully warmed up, this happens only when car is idling.. it idles quite low @ 600rpm. Plugs are new, pcv, vvt solenoid..oil fully synthetic mobil1 5-30 .. the car is an RS 2011 with only 71 000kms..

Anyone ..

[Leegamer]

Make sure it is actually the engine. My bottom alternator bolt had worked itself slightly loose once and the slight movement of the alt on the bracket sounding exactly like a knocking engine at idle.

[yaris4eva]

i did the test removed the serpentine still that faint background knock... but when the hood is closed you dont hear it... i filled up with very high octane booster and it started this...