Bouncing rev counter!

[stevew50]

I have an unusual problem with my 2011 Viano 2.2CDI. The rev counter keeps bouncing by about 100 revs when under light load. It generally jumps up then goes back to the same point almost instantly every few seconds. There is no real pattern to it and I can also just feel the car physical surge when it bounces. Gear box oil and filter changed recently and mileage is 130000.
This is my 4th Viano and I have had many problems over the years but this is a new one for me!
Any advice to the cause of this fault would be appreciated.

 

[merc85]

I had this on my s211 5spd, It was the conductor plate in the box.

 

[stevew50]

Thanks for your reply. Was it an easy fix and any idea of cost.
Cheers.

 

[merc85]

The conductor plate (Gen MB) and the plug inc labour and atf flush with filter and gasket was £500

 

[BlackC55]

Very common complaint. It could be a number of things. Get it plugged into a Star firstly.