Remap Advice Mk4 2.0tdi

[TobyMTDI]

I'm far from an expert, but as far as I understand it there's no reason why mapping the ablue out would have any negative effect on the DPF. The adblue (or DEF) is used for SCR (selective catalytic reduction) of NOx, helping to reduce them to N2 and water. The only thing the DPF is good for is trapping soot particulates, so there's no impact from additional NOx. In fact, I think there's actually been research to suggest that NO2 can help with DPF regeneration by reducing the temperature the carbon in the soot is oxidised (i.e. regen temperature), but the detail of that is way above my pay grade!

[gazza31112]

Yea I'm only going by what iv been told on here in the past, I posted about my foglights not fitting because of the adblue tank a few months back, I was also thinking of getting it deleted, then was told without the adblue before long the dpf would be toast. So no expert myself mate
Ended up hacking foglight to bits to make it smaller

Sent from my moto g31(w) using Tapatalk

[Lockstock]

I was under the impression that adblue was necessary to reduce the combustion temperature of unburnt particulates and it was that catalyst that meant a cleaner burn and Less NOx and Soot. So yea, from what I understood in many applications (including our vans) removal of ad blue could affect the lifespan of the DPF. But again this is 'internet' info, so who knows.

As for 150mph out of these vans I would say its 100% likely.. 1.8T petrol VAG cars that produce less BHP and torque (than a remapped tdi) have been clocked over 150. My a4 b5 quattro sport could do an 'indicated' 150mph.

[TobyMTDI]

Hmm from what I've read it seems to be the other way around, SCR reduces NO2 which in turn increases the combustion temp of the soot - so in theory reduces the effectiveness of passive regens. Deleting the adblue system would increase NOx, meaning increased passive regen and less soot.

Here's a quote from a paper that came up when I just gave it a google, but I can't say I've read the whole paper... :

The extent and rate of passive soot regeneration is significantly reduced in the presence of SCR activity especially at high temperatures (>250 °C)

https://www.sae.org/publications/techni ... 8-01-0962/

Anyway, I'm happy to take the risk, I'll let you guys know if my DPF promptly blocks up!!

[Lockstock]

I read the same thing and found it confusing as could be read either way. There is a chemical reaction to deal with the NOx in the NOC, before the DPF which is passive chemical process. but some NOx builds up and then gets through the NOC into the DPF. There is an Active Ad blue process (SCR) that is both chemical and an active regen burn in the DPF, to clear the DPF.

I think without the Ad blue, you will have more 'stuff' building up in the DPF, the question is, whether the lack of ad blue gives a 'dirtier' but more efficient regen than with Ad Blue. I cant find an answer to this anywhere.

I do agree with you though, logically the SCR breaks down the NOx with one of the by products being water, and I cant imagine extra water inside the DPF will allow for a better high temperature regen... unless this helps to atomise the soot and clear the DPF .

Let us know how you get on

edit
re-read the abstract, so it's saying that in the absence of adblue, there is an oxidising reaction with NO2 and soot in the DPF, which along with regens reduces soot. But with adblue as part of the SCR, this competes for chemical reaction with the NO2, and there is less available to passively oxidise the soot. confusing

[Scoobysrt]

Scooby is it possible you were only doing about 90?

I have 18's mate with tires to produce correct rolling circumfrance. Satnav confirms speedo is quite accurate.

You know those times when you wish you hadn't got involved.......

[gazza31112]

@Scoobysrt I do mate yea

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[Lockstock]

@Scooby
hopefully my sarcasm showed through. I'm not sure what the drag coefficient is on the caddy, but around 200bhp should be enough mathematically to get close to 150. So it's totally doable.
Just need long enough stretch of road and the right conditions.. cars with 70bhp can easily get up to 110mph so it shouldn't seem surprising that these vans can shift in the right circumstances