Car juddering

[N50 SUB]

Hi. 

I have recently purchased an A3 2.0tdi and am having juddering when accelerating but only in the top 3 gears and about 2k rpm. It only judders til I get to about 2200 rpm and then is fine til the next gear!? As I get a bit of white smoke on start up I am leaning towards the dpf, does it have one first and foremost? 

Any fingers pointing in the right direction will be appreciated! 

Also a note worth mentioning, it does have a stainless system with decat.

Thanks. 

[Dan3222]

If it’s that Rev specific then the two places I would be starting is replaceing fuel filter and having turbo checked.

A partially blocked filter only shows problems on higher fuel demand, restricting fuel causing judder.

A worn turbo impellercan cause loss of power as it spools to a certain rpm that starts to restrict power.

Might also potentially be the DMF? But this would not cause white smoke!

 

[N50 SUB]

Thanks for the reply and info. 

My mechanic, who happens to be a btcc mechanic as well, test drive the car when he changed the prop shaft coupling and says with the remap it seems as though they have wound the boost up pretty high. So the turbo could be a good shout, the white smoke is only on start up or idle for a few minutes and then there is none, even under heavy acceleration! It feels very quick all through the rev range so I am pretty sure I am not getting any loss of power, may not be related but worth mentioning that at idle the car feels lumpy but the engine sounds smooth although you can feel the car shaking a bit like something that turns is out of balance??

Also the previous owner had the dmf changed to a solid flywheel when he put in a new clutch. Can't guarantee how well this was done as they didn't even bother to change the release bearing!! 

[Dan3222]

Ha, you have changed the symptoms 🙂

If you have shacks night at idle and shaking at a specific RPM then I would suspect, clutch/fly wheel. I would need to see car myself to help any further as this is not straight forward as so much has changed from normal.

Does the water coolant level go down at all on this car? I suspect the two issues have just as much chance of being unrelated or related now.

[N50 SUB]

Hi. I am afraid not changed just added 😂. 

I have always thought it would be down to one thing and not a multitude of errors! 

No the coolant levels have not gone down since I have owned the car, it has been just below max and hasn't moved! 

Guess that's one up for the little Audi 👍

[Dan3222]

The usual suspects for white smoke are water in oil and too much diesel usually caused be leaky injectors.

Dont forget though on cold days both desires and petrol cars ‘steam’ until they are warmed up.