2.5 tdi

[ainarssems]

As asked by christhompson on another thread about TDI engine EGR and wastegate so that I do not derail the other thread. This is about AKE engine in A6 but should be similar for A8 and other engines

EGR-exhaust gas re-circulation, under certain circumstances it opens a valve between exhaust to in-take so that exhaust gasses make it to the intake to reduce NOx pollution. They do have carbon/soot build-up quite commonly which causes intermittent problem progressing to permanent of valve not closing properly and under boost part of air leaks to exhaust causing loss of power, smoke from exhaust and excessive fuel consumption. I am not sure if it is legal but You can blank off EGR valve and delete function from ECU. EGR function also causes soot build-up in intake pipes and manifolds reducing their diameter and therefor airflow and power so I would recommend taking them off and blasted to clean and restore airflow. Ours do work OK most of the time but sometimes it lacks of power and has smoke from exhaust under acceleration. The plan is to blank EGR off , delete it from ECU and have the intake pipe and manifolds cleaned by crushed nut shell blast next summer when I do cambelt change until then I will just disconnect vacuum hose from EGR and blank it off.

Wastegate is internal part of turbo on these engines and it opens up when boost pressure reach certain level to reroute exhaust gasses straight to exhaust not going through turbo and prevent overboosting, if it starts stucking it does not close properly and some of exhaust gasses always leak straight top exhaust causing reduced boost pressure, power at cost of fuel consumption.

[ainarssems]

Just to add to the post above there is no wastegate, instead there is N75 that adjust vanes in turbo to regulate pressure.

I have spent last couple of weeks looking at mapping our A6 with 2.5 tdi AKE engine and A8 2.5 should be very similar. I have made good progress for a beginner and still learning a lot.

We did the first testdrive with modified maps tonight with wife driving and me monitoring through VCDS, unfortunately we had to cut testing session short as the one of the dogs who forced themselves in back seat emptied contents of stomach all over back seat and floor. So I guess that speaks for itself as it never happened before. There is still much to do regards mapping but it feels like another car 1000-2000 rpm and also certainly improved above 2000rpm.

If you look at the picture below that is requested torque map with green lines being old and topping 370Nm and red line new request which should be achievable once I have finished with it topping at 465Nm which is quite a bit higher then 410Nm that I have in 32V S8.

Obviously I cannot touch Neils new A7 3.0TDI's 500Nm but still impressive.

By the way Neil I know you were looking at tuning box but seriously look into what is going inside ECU and you will understand that no add-on box is match for a good remap, the downside is that you cannot resell remap like tuning box.

P.S. I also have new ETKA prices for you Neil, will e-mail tomorrow

[Architex_mA8tey]

Looks like quite an improvement Ainars - it could be that the "dog test" becomes an industry standard method of testing the results hehe

On the tuning box vs the remap issue I know what you mean but one requires flashing the ecu and then changing it back again to return to original spec whilst the other just plugs on and off etc. The tuning box takes the torque from 500 Nm to 600 (650 max) Nm and the Ps from 245 to 295 (311 max) so not too bad. Fuel economy improves from 5% at max speed to 20% at optimum speed

Likr you said it is possible to have the tuning box re-set up should you change cars/engines and also sell it to get some of the costs back etc

Cheers for the price updates mate thats much appreciated