My 2008 C5 2ltr Tdi exclusive tourer has developed a peculiar problem. At idle the engine runs beautifully as it does when the idle is raised with the throttle. When out driving the car can sometimes develop a slight but noticeable shudder/rumble, at about 50mph when coasting down a very slight incline which allows you to apply only light pressure to the throttle. It’s a weird one, doesn’t always do it, conditions have to be just right. The “rumble” is akin to running over the white rumble line on the motorway, or even unbalanced front tyres. Applying power causes the phenomenon to stop. I’ve had it appear as low as 40 and as high as 60mph, and also in 4th 5th and 6th gear by using manual selection. I’m wondering if it’s the auto gearbox developing a problem.
Anybody come across this before?
Thank you.
