D5254T (to 2002, Audi) Turbo System Problem

[theccentric]

Hello Fellow Forum Members and Volvo Enthusiasts ,

My name is Nick, this is my first post in this forum. I am an American living in Bulgaria and the reason why I am posting in the UK forum is because my English is much better than my Bulgarian , and because they don't have the diesel variants of Volvo's "over the pond" so I wasn't sure if the same problems and components apply to both gasoline and diesel engines.

Let me start by saying that I have gone through all the relevant topics / posts here already, and have gleaned as much information as humanly possible before posting here.

Having said that.... About a year and 3 months ago I purchased a 03/00 V70II (P82) 2.5TDi (D5252T - Audi). Although this is the first diesel car that I have owned, I have driven turbocharged cars before and understand the fundamental principles of forced induction systems as well as how the power output should feel. Right from the start I had a nagging suspiscion that the car is not delivering as much power as it should. Last week this suspiscion was verified when I drove a fellow forum members car (same model, year, engine, etc.) and I noticed a substantial difference in power delivery than my own car... I would say about 15 - 20% more starting at about 2200 - 2300 RPM. This immediately led me to believe that there is a problem somewhere in the turbocharging system of my car.

Of everything that I read in other posts, here are the possible culprits:

1. Boost Pressure Sensor
2. Diesel Injection System Valve
3. EGR Valve
4. MAF Sensor
5. The propellor / spooler in the turbo
6. Pressure leak from a loose or split hose / pipe
7. Split intercooler.


From what I have read and learned, I am temporarily ruling out the following (unless someone informs me that I am mistaken):

2. - Diagostics showed that all the injectors are spraying fuel within the specified range for proper fuel deilvery
4. - I have had no symptoms that would point to nearing the initiation of "limp home mode"
5. - I was told that if the prop is loose, I would be getting quite a bit of black smoke during startup and acceleration
7. - I read that a tell-tale sign of this would be an oil puddle under the front of the car. I have no oil leaks anywhere


So, ultimately here are my questions:

1. Am I mistakenly ruling out one of the 4 things directly above and if so, which?
2. Aside from checking for pressure leak(s) from loose or split hose(s) / pipe(s), can the MAF, EGR and Boost pressure sensor be checked for functionality / integrity
3. Can any of the above-mentioned components (aside from the turbo which can be remanufactured at huge expense) be cleaned and/or repaired if need be to avoid having to purchase new, and is it recommended.
4. If no pressure leaks are found (I hear no noises indicaiting pressure loss) where should I begin?


I sincerely thank you in advance for any advice you can provide

[Bernard333]

5 ,6 , 7 very easy to check yourself . Take the inlet pipe off the turbo and check the rotor for play , there should be a little or none . A really duff turbo will cause enormous clouds of white smoke not black , there is no mistaking it and you wouldnt want to drive the car . Lots of posts on the air pipes/intercooler , see hobbyhorse photos for collapsing inlet pipe . Get someone to stand in front of the car and rev hard to see if the intercooler blows outwards , also see photos on the forum showing burst cooling pipes with oil staines .

[theccentric]

Hi,

Just wanted to let everyone know that the problem has been diagnosed and solved. The culprit turned out to be the Mass Air Flow sensor, despite my doubts about it being just that.

Needless to say, after installing the new sensor it's as though I am driving a new car. The effect wasy simply amazing, I was getting tirespin going into 3rd gear.

Manage to find brand new ones from a few sellers off of eBay U.K. for a fraction of the cost from the dealer or Bosch directly... and with a 1 year guarantee. Anyway, thanks for the help to anyone who commented on the thread