A8 4.2 TDI - Are they normally this slow?

[sutherland]

Having had several A8s I now have a 4.2 TDI, which I find disappointingly slow. According to the claimed figures this car will do 0-60 in 5.7 secs. Mine, however, will do it in 7.0 and cannot get below that.

I can find nothing wrong with the car--no fault codes or obvious problems anywhere. The worst I could say is that the gearchange is a little slow--almost as if it bogs down slightly before changing up on acceleration, but I put this down to a typical kind of diesel experience. It's certainly not as Evo Magazine described it in their review: 'Gearchanges glide through the six-speed Tiptronic automatic with a barely perceptible change in engine note, and without any interruption to the remorseless surge of thrust. And suddenly you've wafted into the 155mph speed limiter...'

Is it just the case that the real world performance of these cars is not as claimed or should I be looking for a problem somewhere?

Any advice or experience would be appreciated.

[RanjS8]

Normally people are saying these are really quick...so I m surprised you are saying it is slow. I would get it put on dyno and see what kind of power it is putting out.....also it might be worth while having a look for any obvious boost leaks.

Finally....I wonder if these have a dpf or if the mileage is low and causing carbon build up?....in short I agree I would be expecting far better from a 4.2tdi.

[PsYcHe]

I do notice a little pause on the gearchange, and whilst I've never times the 0-60, it's definitely quick.

[sutherland]

Thanks for the responses.

The mileage isn't that low and I believe they do have a DPF. I could certainly have a look for obvious leaks, but wouldn't that cause a check engine light?

I'd be interested to know what 0-60 times other owners get in real life. I checked it via OBD on several runs, so I think it's fairly accurate.

[sutherland]

I've had a development with the CEL coming on and the following fault code:

004204 - Throttle Valve 2 P106C - 001 - Stuck or difficult to move - Intermittent

I guess this could be behind my poor performance, but I'm not sure what the solution is. I didn't think the 4.2TDI had the intake manifold problems common to the 4.0 or that they had the throttle body problems common to the 3.0. I'd imagine if the valve was really stuck that I'd know all about it.

Normally sticking such a fault code into Google brings up a whole lot of stuff, but this one only brings up a post in Finnish about from a 4.2 TDI owner with the same problem, which he seemed to think was somehow related to DPF regeneration. There are plenty posts concerning 004203 / P106B, which I assume is the same problem on cars with one intake manifold, so I might work out a solution from that.

[Paul r]

Hi,

My 4.2tdi is pretty quick. It pulls in all gears and it shifts smoothly through the gears.

I had an e60 m5 before the a8 and performance Wise, the a8 doesn't feel that far behind it.

Paul.