Jerking passat when cold and slow pull away

[DSG4ME]

No dump valve as such, but it can dump vacuum by opening a valve and letting some air in. That causes the VNT turbo to reduce the vane angle and so lower boost pressure.

So that would be normal then, and nothing to worry about?

I asked my mate last night if his Touran does it, he said it does, but he's only just noticed it 86k, I've had the cover off and checked the air filter, that's clean, so until I get out in her today and have a keen listen I won't know if I've a problem brewing or not yet.

[chesterman]

Hello guys
I have recently bought a nice 2006 Passat 2.0 TDI 140 with a DSG box, its quite high mileage but has been looked after.
I have read through this thread with great interest

When I bought the car I had no problems at all, but now I am having the same issues that have been described here.
The only changed i have made are a KN air filter and I have changed the diesel fuel filter, and if i am not mistaken, the issue has arisen since then..

When I begin to drive the car from cold or when it’s been standing, I seem to get a hesitation or jerk at about 1500rpm. I would say with a light throttle, does not seem to happen when accelerating properly, but if I try and stay at about 20mph in 2^nd gear at roughly 1500rpm, it jerks, it’s as if the car is trying to change gear but can’t ?
As soon as it warms up its fine, the car runs superb and the DSG gearbox is sublime. I have owned other auto box cars and I have been very impressed with the DSG box
Is there a definitive opinion on this issue now?
Thanks

[RichardSEL]

It's definitive that DSG ATF and filter should be changed every 40k miles. I'd eliminate the box before going any further. If if hasn't been done then it should.

Is your jerk only under load?

Is your KN air filter the oiled one? Engine might respond to a re-adaption in VCDS, I'm not a Derv head so not sure what adaption scripts for TDi engines are available in current version of VCDS. I know some are there in the current version though...

[chesterman]

Hello
Thanks for the reply
I live on a sort of one way system, i can only do 20mph when leaving the area, so i notice it first thing in the morning mostly when i leave for work
Keeping to 20mph, the car is doing approx 1500 to 2000rpm in 2nd gear, and it tends to jerk at that rev range and speed, its not under load, more of a constant speed and feathering the throttle as it were.
To me it seems as if the car is " hunting " or lacking fuel or something, its weird
After a few minutes its fine, strange one !

[niall campbell]

My A6 if parked on a slope, front facing or back overnight will start as if there is air or leak in my fuel system , leaking injector etc

When replacing the diesel filter, did you replace the " O " rings supplied ?? You could smear the new O rings with fresh oil to help seal from air intake/ fuel leak

You could also smear some Vaseline over the fuel pipes at the filter to see if that helps, or indeed look to see they are pushed on correctly , not pushed on too hard over the raised stop points, allowing fuel to leak & air getting in.

If those checks are okay, then look at replacing the air filter back to an original one

However, if the problem is at a cold start up and disappears , it sounds like air leak, injector leak , glow plugs at a push, coolant temp sender unit

[chesterman]

My A6 if parked on a slope, front facing or back overnight will start as if there is air or leak in my fuel system , leaking injector etc

When replacing the diesel filter, did you replace the " O " rings supplied ?? You could smear the new O rings with fresh oil to help seal from air intake/ fuel leak

You could also smear some Vaseline over the fuel pipes at the filter to see if that helps, or indeed look to see they are pushed on correctly , not pushed on too hard over the raised stop points, allowing fuel to leak & air getting in.

If those checks are okay, then look at replacing the air filter back to an original one

However, if the problem is at a cold start up and disappears , it sounds like air leak, injector leak , glow plugs at a push, coolant temp sender unit

To be honest it has not been too bad past couple of days, the weather has been cooler, not sure if that matters.
Yes I replaced the o ring when i changed the fuel filter, perhaps I should use a better quality fuel filter
Yes the KN filter is the oiled type, perhaps i may change it back to see if it makes any difference
Cheers

[Quatrelle]

Best to do one thing at a time and check if it works, otherwise you'll never know what the problem was - apologies if I'm teaching granny here.

[chesterman]

To be honest it seems to have been ok this week, but its been cooler here. Today I went back to me car in work and it showed 22 degree outside temperature, and it did straight away !

Could be something to do with outside temperatures ?

Cheers

[RichardSEL]

See if there's been anything reported in a VCDS Autoscan? Where are you? I'm SE London
Here's the URL for someone perhaps closer who'll do it for beer tokens:
https://www.google.com/maps/d/viewer...5cfcb6158e0447

[chesterman]

Nice one, I am in chester, Cheshire