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Audi A3 BKD TDi 2007 - Over boosting, code P0234 - Fixed #

Posted by Luke Browne on April 13, 2012, 1:39 pm

Year of Manufacture *: 2007
Engine Size and Code *: BKD
( Optional ) Scanner Used: KTS, VCDS. Picoscope
( Optional) Fault Codes: P0234

Came in with intermittent lack of power (suspect limp mode)and the above code deleted and has not returned or lost power. Constant whistle/wine from the turbo and actual values showing peak boost of 2999hPa! every time
scoped boost sensor, good waveform and flat lined at 4.5v over the high boost period so sensor seems to be ok.
The vane control rod appears to move effectively with mityvac (starts to move at 5 inhg and stops at 18) is it possible the vanes sticking is causing this? if so is it worth trying a cleaning agent i.e innotec 3 part product?
Any replies appreciated

Re: Audi A3 TDI- overboosting

Posted by Bradley Kingsley on April 17, 2012, 10:19 pm, in reply to "Audi A3 TDI- overboosting"
Message modified by board administrator April 18, 2012, 10:45 am

I know you say the vane control is moving but could it be sticking? I have found if you can remove the rod or housing area and rattle the vane control lever back and forward a little further each way than it normally moves to remove any possible tight/sticky spots this can cure a overboost situation.
Good luck,

Re: Audi A3 TDI- overboosting

Posted by Shaun Dale <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2719' width='330' height='300' border=0 style='border:none;'> on April 21, 2012, 12:21 pm, in reply to "Re: Audi A3 TDI- overboosting"

Hi Luke,
Not sure if I'm teaching Granny to suck eggs but...
You say the control rod is moving well, how far? from memory they move about 20mm, it's quite a big movement IIRC.
Have you checked for good vacuum in the system, and does it hold when you stop the engine?
Shaun

Re: Audi A3 TDI- overboosting

Posted by Luke browned <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1817' width='330' height='300' border=0 style='border:none;'> on April 22, 2012, 11:17 pm, in reply to "Re: Audi A3 TDI- overboosting"
Luke Browne

Thanks for the replies guys .
Vacuum supply and control are fine ( road tested with gauge in line to the control actuated supply) full vacuum at low speed which decreased as engine speed increased till full throttle and 0 vacuum. ( am i right in thinking these will revert to full boost if the vacuum supply is lost?)
There wasn't as much movement on the rod as that 10mm at the most?
Anyway i gave the innotech turbo cleaner a go which lowered the peak boost (still slightly higher than specified value) customer has agreed to try out under the condition should the symptom return a new turbo will be required. has been a few days and i haven't heard back so fingers crossed

Re: Audi A3 BKD TDi 2007 - Over boosting, code P0234 #

Posted by Derek Sumnall <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5381' width='330' height='300' border=0 style='border:none;'> on April 23, 2012, 4:35 pm, in reply to "Audi A3 BKD TDi 2007 - Over boosting, code P0234 #"

Hi Luke

Had similar problem with Suzuki Grand Vitara 2.0 HDi
(see Dec 5 2010 Fixed & Gone Forum)

R-MC 3e sorted it and not just short term either as the vehicle is still running perfectly today.

Not just once but many times on other cars.
Audi VW group seem worst offenders on sticking VNT's. Had Seat Leon and Golf both with BKD engines in same week this January.

R-MC 3e can be purchased solely from SP Diagnostics under the brand name ReViVe.

Think Mr Amor has gone to sleep on this post.
Wake up Andy.

Derek

Re: Audi A3 BKD TDi 2007 - Over boosting, code P0234 #

Posted by Derek Sumnall <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5381' width='330' height='300' border=0 style='border:none;'> on May 19, 2012, 12:35 pm, in reply to "Re: Audi A3 BKD TDi 2007 - Over boosting, code P0234 #"
Derek Sumnall

Anyone in Stoke on Trent area might be interested in the Sentinel article by John Swift,Friday 25th.

It highlights this problem with modern diesel vehicles if not driven hard occasionally.

Fixed #

Posted by Luke Browne on May 24, 2012, 11:17 pm, in reply to "Re: Audi A3 BKD TDi 2007 - Over boosting, code P0234 #"
Message modified by board administrator May 28, 2012, 1:08 pm

Went ahead and replaced the turbo on this (genuine, new unit)
Once side by side the difference in movement of the vane control shaft was reasonably obvious. The movement on the new unit was almost twice that of the old and much smoother, also the new unit took less vacumm to begin moving and more to achieve full travel.
On the road test observing the specified and actual boost the values were much closer together. Although under full boost in 3rd gear the specified was at 2.5bar and actual was at 2.65bar
it would quickly drop to just below the specified value clearly showing full control of the boost pressure. Thanks for all your inputs, much appreciated.

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