Irmantas

Hello why my AUDI A8 D3 3.7 could pulsate at idle when engine is hot rpm is bouncing from 640 to 680 and engine sound is like pulsate too, I've tried to remove oil cap and this was strange because rpm stopped bouncing and engine starts working fine without any pulsating sound

Jack88

That removing the oil cap helps makes me think of a PCV valve issue. Beyond that, no idea.

Irmantas

hmmm I checked in another videos and saw that when PCV valve is broken than it sounds really weird

Jack88

Usually, but not always. Do you feel a decent vacuum if you put your hand over where the oil filler cap goes when it's off?

Irmantas

No I don't feel any vacuum if I put my hand over oil cap if it' off. Its so strange how oil cap could immediatly remove rpm bouncing and pulse sound. Also I have tried to change MAF

ltooz_a6_a8_q7

Check all vacuum hoses