A6 auto revving slightly

**tubbsy99** · 14-09-2011,07:23 PM

Hi all,

I have noticed something strange with the A6 this past week. When I amdriving at a steady speed and take my foot off the accelerator, like normal therevs drop to around 1000 rpm. But i have noticed at this point something thatfeels strange to me, the car revs gently between 1000 rpm and sometimes up to1200/1250 rpm and continues to do this until i either slow down or i put myfoot on the accelerator again. It is almost as if the car is hunting for anidle if that makes sense. Normally this wouldn’t bother me but where the car isgently revving you can feel a rocking motion as such due to the revving. It’senough to be annoying and wanted to find out if anyone else has this problem oreven if it is a problem.

The car has just had a full service by my garage and the following changed:

Full service

Oil and filter change

Air fliter change

Gear box oil and filter change

Fuel filter change

Coolant change

diff oil change

Power steering oil changed

Brake pads changed and brake fluid changed

I did take it back to the garage and they found a fuel pressure regulatorfault code or something to that effect. They siad this might have been due tothe new fuel filter being changed. They cleared the code but the problem stillpersists.

Any ideas guys?

Cheers

Tubbs

**saltyseaman** · 15-09-2011,07:42 AM

I have noticed that mine does it too.
Although at higher speeds when you lift off the throttle, the car seems to coast more with little or no engine braking.
Its only at lower speeds when I lift off the throttle that the "problem" you describe exists. I have almost convinced myself that its just the auto box deciding whether to downchange or not?

I have a 3.0 TDI auto Le Mans

**Peter D** · 15-09-2011,08:20 AM

Turn the A/C off for a few days and see if it still revs by itself. Regards Peter

**gianton** · 15-09-2011,10:18 AM

This happens to me only when I go downhill and the engine is cold. Once the engine is warm this doesn't happen.

**saltyseaman** · 15-09-2011,01:24 PM

Yep! forget what I said, I have to agree with what Gianton says. I just went out to the park with the dog and on the way back when the engine was up to temp, it didnt happen.
What causes this? I have no idea.

**gianton** · 15-09-2011,01:29 PM

Might be a way to warm the engine faster. Diesels engines get warm harder than petrol ones.
Maybe someone with a petrol engine can chime in to confirm that.

**Guest 2** · 15-09-2011,02:46 PM

Can't say I've noticed this myself when driving. My engine is currently warm so I will have a look when its cold.

**gianton** · 15-09-2011,02:53 PM

I live on the top of a hill and every morning I have to drive downhill on the way to work. This revving up and down was from the day I got my car 4 years ago. I remember my ex BMW 528i wasn't doing that.

**Guest 2** · 19-09-2011,12:52 PM

Noticed this morning that my car does this too, never noticed it before until the question was asked.

Seems to be normal

**tubbsy99** · 19-09-2011,01:09 PM

The slight revving wouldnt bother me at all, its just the hesititation in the engine that makes the car feel like it rocking back and forth slightly when not accelertaing that is a little annoying. It just doesnt feel smooth, this being my first auto i have nothing to compare it with but ive never experienced this feeling with any other car even when as a passenger in an auto.

I did take it back to my garage and they did find a fault code which was the 'fuel pressure regulator' (didnt get the code unfrotunately). They said this might have logged when they changed the fuel filter. They cleared the code but it still does it. They have the car again to do a deaper check. I will let you know if anythign comes up guys.

Tubbs