Oil in PDF ?, Audi A4, 2.0 TDI BRD 170BHP

[Sebastian S]

Hi Guys,

My A4, B7 2.0 TDI (BRD Sad) 170 BHP have lately been given a lot of problems. (all Siemens injector replaced with x-models)

10 days back it would not pick up speed like it was having a trouble spinning up the turbo. It started smoking heavily and the DPF started giving warning light and it went into limp mode.

Got it home and found the well know problem "P0299 Under boost" Did all the easy checks for: vacuum leaks, turbo to intake pressure check. Checked all the vacuum actuators and finally changed the N75 and also the intake switch valve. Still no solution. (Changed the diesel filter and airfilter just to be on the safe side. )

At this time the car could not even idle for more than 10 sec.

Car have done 110k and sofar I had not suspected the turbo as it seemed to be spinning nicely on the intake side. I got the idea the turbo could be jammed on the exhaust side and the connecting axis broken. (Audi confirmed that it happens now and then ..) Got the replacement turbo mounted by still the same problem Sad By now I was sure it was the DPF. Cut cleaned and remounted.

Car ran like a dream for 24 hours then the same problem again... Today..

My theory is the DPF is again getting blocked by oil coming from intake due to high positive crankhouse pressure in the rocket valve cover due to worn piston rings or perhaps leaking injector seats/sealing’s/o rings ?

The CVS is blowing heavily from the rocket valve cover to the turbo intake and even when removing the filler cap a lot for air coming and even "oil-spray"

Any one pls. comment on this "nightmare" I hope it is due to the injectors letting compression into the rocket valve cover and will next go for compression/cylinder leak test.

Any other ideas ?

Long story in Danish-English Smile


Thanks,
Sebastian

 

[lynallbel]

If you cut and cleaned the dpf and it cured it even for only 24 hours the dpf must be shagged, so why not cut and gut it?
Simple check for worn rings, with motor running remove oil filler cap, little bit of puffing and oil mist is fine, chuffing like a steam engine is not okay.
When a turbo shaft fails it normally dumps all the oil out asap and you know pretty soon its gone!

 

[Sebastian S]

Thanks for the fast reply.
I would love to scrap the DPF byt Danish rules and regulations permits…
The old turbo turned out not to be broken on the shaft and perhap not even leaking as the problem with the clogged DPF is back.
Compared the rocket cover breathing today to a another BRE today I guess it is more or less the same.
Would a compression test show wrong piston rings ?
Found the Audi is having a repair note on leaking O rings at the injectors. Turns out ECU will compensate given additional fuel that can also clog the DPF and even very fast. Makes sense ?

 

[lynallbel]

Im not sure how the injectors seal into the head, but would be surprised if an oring can cause that sort of failure, unless the fuel rail is cast into the cylinder head, which if its common rail I doubt.
In the uk they have bought out a new regulation for the annual mot, saying if a car had a dpf fitted from new it must still have one fitted, BUT they can only do a visual inspection, so what people do is gut the cat and reweld it and get the engine remapped by a tuner who tells the engine dpf no longer fitted, so no warning lights come up on the dash.
Compression test could show up worn rings, but again if its ran fine for the 24 hours I would say the engine is fine.
Google leak down test, but I still reckon you need to get the cat gutted and that will sort it, I realise it against your countries regulations but as with all laws theres ways around them!

 

[lynallbel]

Heres one I found, you should have more success and know what to search for, I did notice they are very careful with their wording!
TChip Tuning - chiptuning, tuning, motorsport, engineering, diagnostics

 

[Sebastian S]

Seams PD injector 1 is misbehaving that could support my theory on the bad o-rings. Any ways will check all the PD elements and change the O-rings yet another 200 EUR… And Monday “cut and gut” the PDF. If I go with the same HP and can live the warning lights is remapping needed ? I will maintain the EGR system.

 

[lynallbel]

I didnt realise it was a pd lump, had same set up in my old land rover td5, also have same o ring problems
I dont know if you can continue to use it with a gutted dpf without a tune/remap as the car may see it as a fault and flag it up.

 

[Sebastian S]

Yes the A4 B7 2.0 tdi BRD from 2007 with Piezo electric Siemens PD injectors all changed between 2009-2012 :-(

 

[lynallbel]

On the TD5 engine the o rings use to leak, but iirc this cause starting problems, there were also problems of the cylinder heads cracking on the internal fuel galleries, but they didnt eat there camshafts like the vw/audi version!

 

[Sebastian S]

Changed the O rings today. Do not think that was causing the problem. Have also removed the PDF (again) and will have it "gutted" Monday. Still not sure on the remapping though. Had a talk with some BMW guyes that said no need to remap and they gut the PDF on the 530/535 all the time. Guess I will try it without the remap and see how things are. Hope the worst thing that can happen is limp mode and some warnings. Still worried I could not find the root cause of the problem.

 

[Darren198712]

It will go into limp mode. Speak to rick at unicorn

 

[Sebastian S]

No it is not going into limp mode it even cleared the DPF warning

But the root cause of blocking the DPF in the first place is still there and now I am sure that it is overfueling badly at low rpm when the turbo is starting to kickin. Once it is over 2000 rpm it drives normal with "no" smoke.

Disconnecting the vacuum for the turbo actuator it runs normal with no overfueling but ofcause also no boost.

I am now almost sure it is due to MAF fauling or parhaps the Charge air pressure sender G31 placed on left intercooler.

Any one familiar with failing MAF ?

 

[nansi_2005]

Sorry for my english but i was reading that some people remove the DPF inside so when they need to pass MOT is look ike DPF is in place! I have the same BRD and my injectors are replaced 2012 in Audi ! I have no problems with the DPF now but i think as soon as i can to remove the insides dpf and to remap the car !
My car was scanned with profesional scanner and it said that DPF is 43%... never seen my warning lights and i hope to don't see them !