Its a mild coil pack or a boost leak. Do you have a gauge to see your boost?//////

 

I've done that and I don't feel like it makes the engine run any differently, but the noise of the injection system is definitely more pronounced without the cover off.

I would get it over to the dealership. They really do know these cars inside and out and even if you don't want to pay their prices, if nothing else, it will give you an idea of what is wrong.

 

Thanks 2wdBlazer and KingWulfgar. My car is currently at the dealers. They have told me that my Turbo valve and Drive belt need replacing. That is going to cost me £476 inc. labour.

They are not sure whether these would resolve the problem though but they will test it after and come back to me.

KingWulfgar thanks for taking the time for checking your engine. I will definitely point this out to them.

 

Hope it all works out for you and you get it back to top condition. After only about 2 months, I love my A4 and hope to get many years of service from it (I keep cars pretty long-term).

 

Okay as promised - update. I've got my car back now with both the Turbo valve and Drive belt replaced. When I started the car, there I noticed an improvement straight away. There was just a very slight vibration on the steering but definitely not on the car seat.

I tested it by driving around for a couple of miles. On the move, no vibration at all. At idle (that is, when I stop at traffic, just a very slight vibration on the steering. This I can live with as the condition has improved a lot.

One thing I have just noticed though (which I probably should have noticed since the problem started) is that the idle speed is actually below 800. I'd say it is roughly about 760. I'm not sure if that is correct.

 

That sounds about right. Others can weigh in, but low idle speed is one thing I noticed when I first got mine.