I wanted to take the opportunity and introduce myself briefly and throw a few questions into the room regarding the A8 2.5 TDI automatic into the room. So if you don't want to have a personal feel, you skip the area with ***
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My name is Jan, I am 29 years old, comes from Osnabrück and has been driving an Audi A8 BJ ́98 since January 2009.
Originally, the car purchase was meant as a luxurious "workhorse", as I had to drive about 100 km every day due to my work journey. The A8 was intended as a "winter car", a replacement for a Toyota Supra. We have also screwed on these vehicles regularly and with great success. I have revised complete engines and achieved performance increases of about 100%, which was also durable and did not give up the spirit after 3 motorway departures, meanwhile my Supra drives with the same performance increase and "own-building engine" proud 30,000 km.
Well, back to the A8. So far, I have gained experience in Japanese and exclusively turbo-petrols. So things like "freewheelers", needle pumps and automatic gearboxes" are getting lost. But it doesn't matter, because in principle, I'm capable of learning.
Meanwhile, my "workhorse" has really grown to my heart and so quickly I will not want to give it back. So I got some basic equipment like VAG.com and a little repair manual. So much in advance.
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To my questions:
1. Cruise control
I'd like to upgrade a GRA, also called cruise control.
The steering wheel to dismantle incl. Airbag, etc. should not be the problem, but I wonder if the A8 2.5 TDI BJ 98 already has "e-gas", i.e. an electronic accelerator pedal, and you only need to replace the GRA lever and unlock the software via OBD i.e. Vag.com, or whether other components such as vacuum storage, additional control units or similar have to be installed?
If that's so easy, does someone have such a lever to sell through a battle vehicle or can someone give me the necessary components (possibly with part number)?
2. Multi-performance
In advance: The machine is ready to re-use the needle pump, the timing belt is changed and the turbocharger is revised.
Okay, the 2.5 TDI will never be a racer, that's all it is. It should also really remain within the manageable framework. But I understand that the 110kw 2.5 TDI with 110KW / 147PS is the same machine as the same A8 Quattro with 132kw / 180 hp.
Ergo seems to be regulated by charging pressure and tax times (Is there any tax time for diesel? Less, isn't it?)
Now I don't want to change my own freely programmable control unit Greddy Emanage Ultimate and solder cables to the original ones, which would be nice to use and many possibilities, but also overkill.
So there are three possibilities for me:
a) One of these diesel tuning boxes. The question here is whether it is not only such a resistance in the air mass meter that changes the values to the control unit and this with false air data fools around to persuade it to inject more diesel. I don't really want that kind of thing. Or are these additional boxes of advanced complexity?
(b) Wastegateshimming
The very cheap method. The wastegate from the turbocharger is tightened slightly more, thus generating more preload and it opens later. Ergo: Longer and more charging pressure. If the method had not been exaggerated at the Supra, the control unit controlled the extra power, i.e. the fuel/air ratio was adjusted via Lambda measurement. Is that possible with the 2.5 diesel?
c) Knfeldtuning via OBD Vag.com.
So something would of course be the taste par excellence, in other words, would, law the case my hypothesis with the same engine from Quattro is correct, the safest method being because Audi has designed the machine for the extra power. So OBD plugs in, play up new field and look forward to additional performance.
Should this work as I don't know, does anyone possibly have the right software at a small price?
3. Gear oil flushing
I would like to completely flush my automatic transmission and change filters. In principle, the Tim Eckard method is quite simple and you can reproduce it relatively with some knowledge. But I don't have the time to do that at the moment, so I decided to have it done "professionally".
It is questionable where and if someone has had experiences with the A8 2.5 TDI ATM?
Normally I would have gone to Dortmund to see ZF. They were supposed to do that. Or other suggestions?
I thank you in advance for your help and hope that I will soon be able to contribute something with my knowledge.
