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VW Passat 2.0 2007 - Over boost problem, code P0234 - Fixed #

Posted by Phil Kingdon on August 21, 2013, 12:49 pm

Year of Manufacture *: 2007
Engine Size and Code *: 2000
( Optional ) Scanner Used: sous
( Optional) Fault Codes: p0234

This has been a frustrating journey, to say the least!
vehicle arrived with overboost problem, manifests at about 80-90 mph 5th or 6th gear or occasionally at absoute max 3rd gear, has had boost sensor all vacuum pipes renewed n75 valve, and recon turbo from essex turbos.
Turbo was definatly sticky before work began and has light whistle from bearing..n75 and boost sensor fitted after vehicle had arrived back still no good.
p0234 code present each time.
What else can cause overboost?
Blocked inlet?
Eventually going to lose my lisence test driving this blighter!
Thanks for reading.. phrom fill.

Re: vw passat

Posted by tony bickers <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5143' width='330' height='300' border=0 style='border:none;'> on August 21, 2013, 2:33 pm, in reply to "vw passat"
Tony Bickers

Can you graph actual against desired boost? I have just had one of these with that code and it was turbo,Ross tech wiki suggests all that you have done already

16618/P0234/000564
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Contents [hide]
1 16618/P0234/000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
1.1 Possible Symptoms
1.2 Possible Causes
1.3 Possible Solutions

16618/P0234/000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
Possible Symptoms
Malfunction Indicator Light (MIL) ON
Boost Pressure too high
Reduced Power Output
Possible Causes
Hoses incorrectly connected, disconnected, blocked or leaking
Boost Pressure Control Valve (N75) faulty
Boost Pressure Sensor (G31) faulty
Turbo Charger stuck/faulty
Possible Solutions
Check Charge Pressure Control System
Perform Output Test (to check the Turbo Charger)
Perform Basic Setting (to check the Charge Pressure Control)
Perform Pressure Test to locate Leaks
Check/Replace Boost Pressure Control Valve (N75)
Check/Replace Boost Pressure Sensor (G31)
Check/Replace Turbo Charger
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Re: vw passat

Posted by Phil Kingdon on August 21, 2013, 3:02 pm, in reply to "Re: vw passat"
Edited by board administrator August 22, 2013, 11:59 am

Thanks Tony... Update, just removed inlet manifold the flaps in it are missaligned with no bearings left between flaps on no 4 end of engine.
There is a little plastic ring with a locating peg next to the actuator, this was out of its seat allowing the runner to move over by 3mm.
Could this be our issue?
The flaps are also not round anymore!
Thanks... fill.

Re: vw passat

Posted by Glyn Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on August 21, 2013, 4:28 pm, in reply to "Re: vw passat"
Glyn Morgan

Hi Phil,

I find the following procedure excellent for finding the cause of overboost.

VNT Pico test

Regards Glyn

Re: vw passat

Posted by phi kingdon <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1433' width='330' height='300' border=0 style='border:none;'> on August 21, 2013, 5:14 pm, in reply to "Re: vw passat"
Phil Kingdon

Looks like a good bit of kit, I have a pico... may have to have a look at that, in this case as i have new turbo new n75 and boost sensor i hope its all ok there, not sure if this manifold woud cause this fault.
Cheers fill.

Re: vw passat

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on August 21, 2013, 8:53 pm, in reply to "Re: vw passat"
Jonathan Morgan

As per Tonys Post.
Can you data log or graph desired boost against actual boost & N75 duty whilst flooring it in 3rd gear to see how the boost control is reacting, also useful to see what is actually occurring on the vac actuator with a vac gauge.

Do the atmospheric & boost pressure sensors tally with each other with the ignition on engine off etc.......

Does the manifold runner vac actuator hold vacuum on a mityvac?

Re: vw passat

Posted by phil kingdon <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1433' width='330' height='300' border=0 style='border:none;'> on August 22, 2013, 8:31 am, in reply to "Re: vw passat"
Phil Kingdon

Thanks, unfortunatly for some reason my solus wont give me any live data at the moment on this car... not sure if it should,but its not on the menu.
the inlet manifold runner does hold vacuum.
Our local vw dealer sells lots of these manifolds but doesnt know the faults they have... would be nice to know what they suffer with and symptoms.
Sorry if I seem narrow minded on this one... am ordering vagcom today if poss so may be I can have more info soon.
Thanks to all who have posted so far.
Fill.

Re: vw passat

Posted by Kevin Apps <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on August 22, 2013, 10:44 am, in reply to "Re: vw passat"
Kevin Apps

Phil
" some reason my solus wont give me any live data at the moment on this car... not sure if it should,but its not on the menu."

How do you put up with that? and why ?

Expert mode ?

Kev.

Re: vw passat

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on August 22, 2013, 10:59 am, in reply to "Re: vw passat"
Jonathan Morgan

Solus can get in deepish on VAG with expert mode.

Boost pressure "actual" & "desired" are in MVB 11.

EGR "actual & desired" in MVB 03.

Re: vw passat

Posted by C Baxter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3362' width='330' height='300' border=0 style='border:none;'> on August 22, 2013, 1:23 pm, in reply to "Re: vw passat"
Chris Baxter

Had a couple of these, both ended up having turbo vac unit as they also have pressure position sensor in them. Check in measured values 011 with full vac needs to be 0.65-0.85v and no vac 3.30-3.90v. Bit of a pain to fit but do with full vac applied and set by screwing nut down which lifts position sensor to 0.76v.

Re: vw passat

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on August 22, 2013, 7:14 pm, in reply to "Re: vw passat"
Jonathan Morgan

The vac unit with position sensor is on the 2.0 Common Rail engine. When the vac unit fails it typically logs underboost & runs with noticeably reduced power.

This is a 2.0PD if a 2007 model.

Phil do you have the engine code to clarify what you are looking at?

The more info you provide the more accurate your responses will be.

The info above is good for the 2.0 Common Rail, but doesn't apply to your (presumably) PD engine?

Re: vw passat

Posted by Phil Kingdon on August 23, 2013, 10:55 am, in reply to "Re: vw passat"
Edited by board administrator August 23, 2013, 1:41 pm

Thanks guys... lots of input, yes solus is delayed in going for repair..dealer has no loan tool at moment. on/off button playing up too, seems to read all other cars ok as long as you can switch it on!
That aside, yes pd engine code is BKP..
I know I keep harping on about this inlet manifold, but I showed it to the customer who has agreed to fit one on the basis that it is very knackered and may let a flap go, this could cause engine damage!
New bit on order.. will update when fitted.
Thanks again, Fill.

Re: vw passat

Posted by phil kingdon <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1433' width='330' height='300' border=0 style='border:none;'> on August 27, 2013, 4:35 pm, in reply to "Re: vw passat"
Phil Kingdon

Well, this did not fix the fault.. will now wait for my new vagcom to arrive.
At least I know this wont self destruct the engine if the manifold failed on a test drive, needs a fair old caneing to make it break down!
Update soon, (I hope!)
Thanks for input, fill.

Re: vw passat

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on August 27, 2013, 7:03 pm, in reply to "Re: vw passat"
Mark Carter

>>> as i have new turbo new n75 and boost sensor i hope its all ok there <<<

I understand what you are saying but it would not be the first time a "new" component is faulty.

Glyns test would prove all of the above one way or the other.

You can make a simple pressure transducer for under Â£50 from Maplins (including the box to fit it all in)

Mark

Modern cars, Its all wizardry and witchcraft

Fixed #

Posted by Phil Kingdon on September 6, 2013, 1:26 pm, in reply to "Re: vw passat"
Edited by board administrator September 7, 2013, 12:59 pm

FIXED!
Sorry abut delay in posting fix, my customer has been to Cornwall trying out the car, he has reported back all is well now.
We rigged in a vacuum guage into the actuator hose for turbo, and ran it in tandem with solus showing desired boost and actual.
Eventualy we could predict when the fault was going to occur,generally when boost reached about 500 mb over desired, this would coincide with a momentary blip in the vacuum line to the turbo.
By a process of elimination disconnecting the other solinoids from the vacuum system we found the solinoid for the intake tract was leaking vacuum, swaped it out temporarily for a working N75 valve and the fault was gone!
Thank you very much for all help.
Guess what?
Got another one in next week, this one has aso had turbo off and cleaned!

Re Fixed #

Posted by Phil Kingdon on September 6, 2013, 5:45 pm, in reply to "VW Passat 2.0 2007 - Over boost problem, code P0234 #"
Edited by board administrator September 7, 2013, 12:59 pm

Thanks for help

Re: VW Passat 2.0 2007 - Over boost problem, code P0234 #

Posted by Glyn Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on September 6, 2013, 6:29 pm, in reply to "Re: VW Passat 2.0 2007 - Over boost problem, code P0234 #"
Glyn Morgan

Hi Phil

Well done on your fix

the solenoid for the intake tract was leaking vacuum

Just to clarify are you saying the leaking solenoid was causing a vacuum increase in the circuit to the turbo actuator diaphragm ?

Regards Glyn

Re: VW Passat 2.0 2007 - Over boost problem, code P0234 #

Posted by phil kingdon <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1433' width='330' height='300' border=0 style='border:none;'> on September 9, 2013, 3:31 pm, in reply to "Re: VW Passat 2.0 2007 - Over boost problem, code P0234 #"

Hi Glyn, mmmm confused me too.
I know there was lots of variation on the dial of my vacuum guage as vehice went into overboost.
Could the disturbance and restoration of vacuum cause a quick blip on the actuator?
Not sure, but it certainly got rid of the fault.
What do you think?

Thanks.. Fill

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