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Old 12-01-2016, 11:59 PM   #15 (permalink)
Master EcoModder
Join Date: Feb 2014
Location: Missoula, MT
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Dark Egg - '12 VW Touareg TDI Sport AWD
90 day: 25.81 mpg (US)
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From what I read trying to research if I want a 6.7, there are active and passive regens. The truck won't say anything on it's own when it goes into active regen unless the DPF is really full. Basically it only sometimes warns you when you really need to let it finish or risk a 100% full DPF that then won't ever trigger an active regen without a trip to the service center. Other times it just does the active regen when it feels like but unless you have some kind of aftermarket gauge like the Edge, you may not notice. If you stop in the middle, it just restarts next run, again if it doesn't finish, it restarts again. With the EGR and DPF in place I would avoid idle at all costs, that really seems to soot the whole system. The passive regen is just working the truck hard enough that it burns it's own soot, so towing or going up a long hill should give you freebie regens. The DEF system actually helps reduce the number of active regens, so some find better MPG with that system although then you have to buy that crap so they end up paying more.

Personally, I would delete the DPF, deactivate the regen, and turn off the EGR but leave it in place. I would do it even if I were leasing the truck or if it was under warranty, although the trucks I have looked at are all out of warranty anyway, and some have the deletes in place already.

if you want to keep it all stock, an Edge gauge or something similar you could monitor the DPF level and learn when it does active regens. Then next time before it gets that point, a higher speed or a downshift may hurt mpg temporarily, but may get the EGT high enough to get some passive regen going. Then slow back down. If you are going to be adding fuel in a regen, you might as well be using the fuel to go faster ultimately getting better mpg overall.
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