2000 Allroad 2.5TDI Vibration and Power Loss

[alanmcgurk]

Hi all,
Hopefully someone can point me in the right direction here...

I have a 2001 2.5TDI V6/Tip Allroad with an intermittent problem.

The long winded explaination.....

On a motorway run... at around 75- 80mph, there is a vibration that can be felt throughout the car, this is then "sometimes" accompanied by a loss in power when accelerating. When I say loss in power, I mean the car vibrates badly (almost like a misfire), it will maintain speed (auto/tip gear changes makes no difference), but will go no faster and there is a big cloud of smoke from the exhausts. This can last 10-15 seconds and will then clear and run smoothly again.

This "sometimes", but rarely happen a lower speads, but then only when accelerating rapidly.

The car is still under a dealer warranty (independent) and has been in and out of their workshop for a couple of months. As this isn't logging any fault codes and their technicians are not allowed to "drive at 75 - 80 mph", they have been unable to replicate the problem.

I've driven with one of of their techs in the car, but the local roads are only B-roads, so typically the car behaved itself!

If it's any help, on a 250 mile motorway run at the weekend, I got around 30mpg.


Sorry it's a bit long winded, but it's difficult to summarise.


Alan

[fjtwelve]

If its black smoke i suspect the N75 valve has failed