Very slight vibration at idle

[Aaron07]

Hi all

I have recently bought a 2010 a6 sline le mans with 120k on the clock. Love the car but i have noticed there is a very slight vibration when its idling. There are no noises comming from it and it doesnt make any diffrence when the clutch peddal is pressed in so dont think its the flywheel. The car drives perfect with no unwanted noises. I have read online that this is just the way these cars are and was wondering if thats true or not. I had a 2.5 v6 before this which are known for being really smooth and i dont know if its just the fact i am comparing the 2. I have also had the car plugged into vag com and it has no fault codes

Any help would be appreciated

[Trevor]

Hi Aaron....welcome to the Forum

I would have it checked at a specialist Audi repairer to ensure that the timing chain/belt is as it should be just to be on the safe side.

After that, I would run some fuel cleaner through the engine to ensure it is running clean and see if that improves things

Let us know how you get on with it

Cheers  Trevor

[niedzial1983]

Engine or gearbox mount could be on its way out

[Aaron07]

Hi thanks for the replys

I had my mechanic look at it yesterday he checked all the mounts/pulleys ect

He found that the air filter was blocked up so he replaced it and cleaned out the box i got the car back and the vibration is gone so thankfully an easy fix ( i never would have thought to check it)

He also changed the brake pads as there was a slight knock when braking and thats now gone too

I changed the oil, oil filter and fuel filter today just to be safe so hopefully thats it for awhile now 

[Aaron07]

Thought it was sorted but sadly its not (i think it was abit of mind over matter) the vibration is still there. Any other suggestions to what it could be

[Dan3222]

Did you try the fuel injector cleaner? It could easily be a partially blocked injector or two? I use Millers (from Halfords), every third fill. In both A6 and T5. If that doesn't help might be worth getting timing checked. belt could be out by a tooth?

[Aaron07]

Thanks for the reply dan3222 

Think i will try injector cleaner next then to rule that out.

I have been looking at liquid moly diesel purge and it has got loads of really good reviews online i will more thank likely get the timing kit changed in the next few months just to be safe as the dealer had no evidence of it being done before

Process of elimination is an expensive job 

[Aaron07]

Hi still no joy in finding vibration so far i have had timing kit and water pump done, blanked off egr to see if it made a diffrence which it didnt, fan belt tensioner replaced the a/c recharged it has been fully serviced and still no diffrence. I have noticed that it does go away when the a/c is turned on. Any other suggestions would be appreciated

[Dan3222]

That's interesting then, when you turn on the A/C or lights etc there is a slight load applied to the cars electrical system so the engine revs very often raise to produce more charge for the battery, infact it's a double whammy for the A/C as the engine drives the A/C pump too. Maybe you idle speed is simply too low? Just a stab in the dark you know!!

what does it idle at with no lights A/C etc, post it on here and see if other people with the 3.0 V6 comment on their idle speed. 

Just for info, even with the clutch pedal down the flywheel (dual mass in your case) is still turning so it actually doesn't really rule that out tbh.

[Aaron07]

Hi thanks for the reply. I checked it today and when all the electrics are off the car idles at 800rpm. If i knew for definit it was the flywheel i would replace it but reading through other threads that is what everyone seems to replace first and most of the ones i was reading was still getting the vibration after. I dont know of anybody in my area that is good with diagnostic equipment to see if they can see anything through the measuring blocks. Any other suggestions on what to check next