Intermittent bucking jerking while driving

[uzi_adam]

Hi Guys,
I've been searching for weeks and tried a few things to sort this issue out but not really getting anywhere.
I recently purchased a 2011 A3 2.0tdi 170 CBBB Black Edition with 80k miles. I test drove it on two separate occasions and all was fine, car had good and honest history.
A few weeks later I noticed it buck while on the motorway, was so slight and minute and having experienced this with bad fuel and a bad filter on my cupra tdi i decided to change the filter out. At the same time I also circulated some liqui moly through the injectors, but the problem was still there.

Basically the car will buck (almost like it is spluttering) at random speeds/RPMs.
I disconnected the air control valve on the manifold and the problem disappeared so I thought that might be the culprit, I replaced it with an original and cleaned as much soot/egr build up out the manifold as I could.
The problem seemed to have gone for a day but returned and was no different than before. One time the car spluttered and stalled after starting it before a long journey, the only way to get around it was if I disconnected the air control valve (butterfly valve/anti shudder valve VDO 03l128063k).

Its definitely not a boost leak, I disconnected the outlet from turbo, capped other end at intake and used my mityvac to test it and it was good.
No black smoke and no fault codes come up (apart from when I take the connector off the valve).
Apart from the occasional bucking (as if it is intermittent fuel starvation) the car runs smooth with plenty of power.
No odd sounds or anything like that.

Can someone please help me out? I'm sure there is an answer/fix for this, the people with similar problems on all the old posts I've read haven't reported back on whether they managed to solve the issue.

Thanks

 

[Kbustera]

MAF

Sent from my SM-G930V using Tapatalk

 

[Reidie87]

buy and OBD reader and it will point you straight towards your issue.
Mine was the same symptoms on a 1.8tfsi and turned out to be a broken wire on the boost pressure sensor plug.

 

[uzi_adam]

I have VCDS but no fault codes.
Anyone else? MAF seems healthy on the measuring blocks.

 

[Spiezels]

I had this on my old Derv for the 3 years I had it.

Would only happen at or around 80mph and on a long journey maybe twice.

Never had a fault code come up or any other issue.

Never found out what it was.

 

[uzi_adam]

Really...no one has a fix for this?

 

[uzi_adam]

Still no further forward with this...today I got in the car to go to work and after starting it died after a few seconds, i went to re start and it was cranking but would not fire up. The only way i actually go it to start was by disconnecting the air control valve!
I really need to sort this, last place I want to send it to is the dealers though.

 

[Marek196c]

bad a/f ratio, check mapping of car and boost sensor

 

[joslinl]

Hi!

did anyone ever find a solution for this? It’s honestly the most Annoying thing ever

 

[Audi A3 S-Line 8p tdi]

Hi Guys,
I've been searching for weeks and tried a few things to sort this issue out but not really getting anywhere.
I recently purchased a 2011 A3 2.0tdi 170 CBBB Black Edition with 80k miles. I test drove it on two separate occasions and all was fine, car had good and honest history.
A few weeks later I noticed it buck while on the motorway, was so slight and minute and having experienced this with bad fuel and a bad filter on my cupra tdi i decided to change the filter out. At the same time I also circulated some liqui moly through the injectors, but the problem was still there.

Basically the car will buck (almost like it is spluttering) at random speeds/RPMs.
I disconnected the air control valve on the manifold and the problem disappeared so I thought that might be the culprit, I replaced it with an original and cleaned as much soot/egr build up out the manifold as I could.
The problem seemed to have gone for a day but returned and was no different than before. One time the car spluttered and stalled after starting it before a long journey, the only way to get around it was if I disconnected the air control valve (butterfly valve/anti shudder valve VDO 03l128063k).

Its definitely not a boost leak, I disconnected the outlet from turbo, capped other end at intake and used my mityvac to test it and it was good.
No black smoke and no fault codes come up (apart from when I take the connector off the valve).
Apart from the occasional bucking (as if it is intermittent fuel starvation) the car runs smooth with plenty of power.
No odd sounds or anything like that.

Can someone please help me out? I'm sure there is an answer/fix for this, the people with similar problems on all the old posts I've read haven't reported back on whether they managed to solve the issue.

Thanks

Air in the fuel system maybe? Was it the fuel filter you replaced? I actually had this problem a couple of times in the last few years. The first time I fixed it was with a new coolant sensor (1) top sensor near battery. It does control the air fuel so maybe this is worth checking. Hope this helps and good luck.