At 4000 rpm ?

[BobC]

I have just test driven a very nice S4 Avant which I am considering buying but I have one reservation.
At 4000 rpm on an open throttle there is a very noticeable clunk or bump from the engine. Worse in 2nd and 3rd gear.
Does anyone have any ideas what it could be? I have asked the seller to have it checked out before we talk money.

Thanks.

[Sql_RS4]

Maybe engine mounts on the way out?

[BobC]

It happens at the same rpm in every gear gear, just more severe in the lower gears. I was trying to find out just what happens mechanically at 4000rpm. Such as cam timing changing or something to do with boost. Any ideas welcome. This car has been chipped, I assume it's not normal for an S4 to do this.

I just noticed this problem was raised back in April, thought to be plugs or coil packs. Was it proven at all ?

[BobC]

Ok, for the record I found the problem.

It was the Y shaped pipe on the throttle body. There was a split which would remain closed until 4000 rpm when there was sufficient boost pressure to open it. Just like a dump valve.

The car goes like it should now.

[Blue_Thunder]

It's metal on the RS4 though!

[TopBear]

It's metal on the RS4 though!

Looks like its been posted in the wrong forum

I have just test driven a very nice S4 Avant