Afternoon!

With all the current furore about the VAG emissions test limits "avoidance" s/w, has anyone any real knowledge or experience of the effects of tuning (re-mapping, component changes, with/without DPFs, etc.) VAG turbo-diesels on the emissions levels and specifically the NOX numbers?

John

My Mk2 Octavia - no DPF - was run with both a tuning box and then a remap and never had a problem passing its MOT on emissions.  As far as I know the NOx emissions are not measured in the MOT

It's a very good question, I'll be hoping that there is someone in the Internet that can offer you some data.  I won't be surprised if not much is forthcoming though.

As octavia5 says, NOx or any other emissions are not checked at MOT on a diesel, only a smoke test.

I'm mainly interested in the UK situation and experiences, but have now found that there is quite a lot on the TDI Club forums in the US - see here:http://forums.tdiclub.com/forumdisplay.php?f=29

Edited 8 October, 201510 yr by jeallen01

Happy to have been proved wrong!

The US has different emission tests and laws which are not currently relevant in the UK

The US has different emission tests and laws which are not currently relevant in the UK

Agreed, but the US forum may have comments that are indirectly relevant, as I am also interested in any real-World evidence/anecdotes as to what the effects are - regardless of what the UK legal requirements are.

BTW, like a lot of people I have always taken manufacturers' declared emissions/mpg figures with a huge pinch of salt because the real-World figures you see in, e.g. Autoexpress and Honest John reviews are generally very much less flattering.

Did you find anything directly relevant to your question on tdiclub John?

I dipped into a few threads and there seem to be some well-informed people around on there, but I haven't really picked up on anything much in the way of data about re-mapping and NOx.

Have you done any better?

My gut feeling is that most remaps are going to focus on performance, with scant regard to - or mention of - any non-MOTable emissions, unless they move in a favourable direction and become a selling point (e.g. better mpg/lower CO₂).

I haven't done much more digging on the subject as I am doing a lot of decorating, but I think you're right - probably the only thing that people do look out for is that there is not too much smoke.

Might take a more-in-depth look as the situation when I have finished all the papering and painting!

I'm up to page 62 (of 653 currently!) of the main thread on TDIclub, and there's a little mention of your question in post 918, and the one that it's quoting.  Haven't tried to find this "equation used to model NOx emissions in diesel engines" yet.

I must admit that I was talking in general terms about the diesel emissions part of the TDIClub forum, and not about any specific threads therein - still decorating (and having major C/H troubles, as well as finishing my complicated Tax Return) and so have not been back to that forum to look further.