Diesel Diagnostics

Post a Response

Audi A6 2.0 PD BRE 2007 - Code P0299 Boost pressure reg control - Fixed #

Posted by Graham Hucklesby on April 10, 2013, 7:40 pm

Year of Manufacture *: 2007
Engine Size and Code *: 2.0 pd bre code
( Optional ) Scanner Used: snap on modis
( Optional) Fault Codes: p0299 boost pressure reg control

Hi

This car came in on the end of a piece of rope after cutting out on dual carriageway,i dont think the fault code is anything to do with non running?
fuel supply to tandem pump/high pressure pump seems poor although it is a steady stream have tried inline pressure gauge but does not register so removed in tank pump to find layer of black "scum" on everything so replaced in tank pump and filter,but no difference engine fires but will not run as before.I think the black scum is possibly injector seals leaking but i do not think this should stop it starting?any ideas or tests i could do would be much appreciated.

thanks.

Re: audi a6

Posted by David Clayson <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1143' width='330' height='300' border=0 style='border:none;'> on April 10, 2013, 10:31 pm, in reply to "audi a6"
David Clayson

Hi

You could find the combustion gases are entering the return to tank side of the fuel system which goes tthrough the fuel filter which will give you the symptoms of air in the fuel

HTH.
David

Re: audi a6

Posted by Carl Ford <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1822' width='330' height='300' border=0 style='border:none;'> on April 11, 2013, 10:59 am, in reply to "Re: audi a6"
Carl Ford

To test your injector seals you will need to attach guage at tandem pump, hold RPM at 2500 pressure should be approx 7.5bar.

Then if you clamp off return and the pressure increases your injector seals are faulty.

Carl

Re: audi a6

Sorry about last post didn't read yours correctly.

What is your low pressure before and after the filter?

Make 100% sure all pipework is back on correctly I have a MK5 BKE Engine code golf sat here which I diagnosed as a low pressure pump causing non start sent back to garage to repair

Next day they towed it back and to cut what could be a very long story short they had connected the pipes on the pump the wrong way round.

Carl

Re: audi a6

Posted by Graham Hucklesby on April 12, 2013, 7:31 am, in reply to "Re: audi a6"
Edited by board administrator April 13, 2013, 11:41 am

thanks for the responses,there appears to be no measurable low pressure just a steady flow which is all i got on a pd passat i checked yesterday.have replaced high pressure pump now but still no difference,fires but will not run,could the injector seals cause this?

Re: audi a6

Posted by Kevin Apps <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2589' width='330' height='300' border=0 style='border:none;'> on April 12, 2013, 7:57 am, in reply to "audi a6"
Kevin Apps

Graham.

Black scum ? algee (jelly like? )

Kev.

Re: audi a6

Posted by Graham Hucklesby on April 12, 2013, 9:09 am, in reply to "Re: audi a6"
Edited by board administrator April 13, 2013, 11:42 am

Kevin
yes thats how i would describe it although the local dealer is saying they are all like it in the tank?

Re: audi a6

Graham.

If it,s jelly like it,s a bacterial fungus.

Kev.

Re: audi a6

Posted by Graham Hucklesby on April 12, 2013, 5:22 pm, in reply to "Re: audi a6"
Edited by board administrator April 13, 2013, 11:42 am

perhaps it needs some antibiotics?

took the injectors out today to check seals but all looks perfect no sign of combustion leakage and seals are soft.before i took them out i tried dissconecting each wiring plug in turn to see if it would start on 3 cyls but no luck.
strange thing is when you first crank engine it fires almost like it is going to start then nothing.is there any way of measuring "rail" pressure on these engines?

thanks.

Re: audi a6

Posted by Graham Bullock <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2744' width='330' height='300' border=0 style='border:none;'> on April 13, 2013, 1:08 am, in reply to "Re: audi a6"
Graham Bullock

Kev's not pulling your leg, Google diesel bug and compare with what you found.

Graham

Re: audi a6

Posted by Jon Morgan <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3190' width='330' height='300' border=0 style='border:none;'> on April 14, 2013, 10:19 am, in reply to "Re: audi a6"

As Carl said - have you checked the fuel pipes are fitted the correct way?
Pipes marked with blue are return, black are supply.

Blackened components in the tank are common on these.
The fuel can reach temperatures of 90C and turns the fuel tank into an aquarium.

The symptoms you describe of flow with no pressure & no relevant DTC's are symptomatic of the return & feeds being switched. The most common place for this to occur is at the fuel delivery unit.

There should be a min of 0.5bar from the fuel delivery unit in the tank to the fuel filter.
There should also be 0.5 bar after the filter.

Filters are known to block.

Tandem pressure needs to be checked at the allen bolt port on the tandem pump with a banjo adapter.
Roughly 3 bar at idle & 10 bar when revved to 4000RPM are healthy pressures. If using an undamped gauge the needle will be break dancing around the dial.

Re: audi a6

Posted by Marc Roberts <iframe src='https://members.boardhost.com/ukautotalk8/info/user=ukat3167' width='330' height='300' border=0 style='border:none;'> on April 17, 2013, 12:42 am, in reply to "Re: audi a6"
Marc Roberts

Will it run on a sniff?I only ask because had same sounding fuel found in tank a tank on one of these once.
mine would not run a sniff,slackened dpf to turbo flange and sprang into life.The fuel when being combusted was very sooty and had blocked it solid however had no code relating to it being blocked only that the boost pressure was not as expected due the strangled exhaust.

hth
Marc

Fixed #

Posted by Graham Hucklesby on April 17, 2013, 9:24 pm, in reply to "Re: audi a6"
Edited by board administrator April 22, 2013, 4:00 pm

thankfully seems to be running fine now but cant tell for sure what fault was, While i was waiting for injector seals i removed egr valve as local audi dealer said they had egr faults with these engines causing non start not sure how egr can prevent start up but while i was checking operation with modis component test i made the mistake of working the small butterfly flap by hand and it slipped on the spindle!so had to replace egr valve.when i reassembled with new inj seals and egr valve it did not start straight away but gave it a sniff and it fired up and has run perfect ever since!
so not very conclusive unfortunately. audi dealer did also mention they had seen cases of these engines with faulty crank sensor with no fault code causing non start.
thanks for all youre help, will post again if any more trouble.
jon"s point about the fuel temp makes sense i saw 65 degrees after a short road test.

graham.

« Back to index

[ Diesel Diagnostics ]