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Discussion Starter #1
Hi there

there's been much written here about remaps, but the focus seemed to be on more power and torque.
I'm rather interested in a remap that aims at better fuel economy, whatever happens to the BHP.

It's for a 2005 T30 2.5 TDi 4motion 130 with about 175k miles, well maintained. It's converted to a campervan, so relatively heavy.

At the very best I've done 37-38mpg (steady 60-65mph on highways), more likely to be 34-35mpg on normal trips with a bit of stop and go. Around town this can drop to 30-32 mpg. I know the 4motion hurts, but this doesn't sound great to me.

Can I expect a significant gain after a fuel-saving targeted remap? Could there be drawbacks in terms of NOx emission?

Thanks for you advice
 

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Can I expect a significant gain after a fuel-saving targeted remap?
NO - maybe a little but not significant.

But 2.5 TDI camper 4 motion (Winter time) I would say your getting the correct figures.

Blow your tyres up harder and better driving style (more using the gears to slow down than the brakes etc)
Remove roof racks etc
Change to smaller tyres (if aftermarket wide ones fitted)
 

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Hi there

there's been much written here about remaps, but the focus seemed to be on more power and torque.
I'm rather interested in a remap that aims at better fuel economy, whatever happens to the BHP.

It's for a 2005 T30 2.5 TDi 4motion 130 with about 175k miles, well maintained. It's converted to a campervan, so relatively heavy.

At the very best I've done 37-38mpg (steady 60-65mph on highways), more likely to be 34-35mpg on normal trips with a bit of stop and go. Around town this can drop to 30-32 mpg. I know the 4motion hurts, but this doesn't sound great to me.

Can I expect a significant gain after a fuel-saving targeted remap? Could there be drawbacks in terms of NOx emission?

Thanks for you advice
You are getting good figures, are you using the onboard readings?
 

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my advice is just get it tuned to have as much power as they can get out of it safely, and then just drive it normally and it will return better MPG.
I got an "eco" remap years ago, and it was a load of rubbish. after a few months I realised that it felt like it had about 5% more power than it used to, compared to having previous cars mapped where the perceived gain was more like 30%. in the end I decided to just get a proper remap (i.e tune it to the safe limit) and the MPG then went up (back to how it was before the remap), and it was better to drive too.
the remap makes the engine more efficient at making power for a given amount of fuel. thats it. you can then choose to drive faster and harder and use more fuel, or go the same speed and then use less fuel
 

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I have the same vehicle, 2006 AXD 4Motion, Kombi so maybe a bit lighter than your camper conversion. I get those sort of mpgs you quote, & think that's normal for these heavy 4wd vehicles, & not bad compared with similar year alternative 4wd vehicles. As others say, relaxed driving helps & these 2.5s have plenty of torque & long gearing so that's easy, & my AT winter tyres definitely dont help but needed. Think you'd have to get a big increase in mpg to cover cost of remap, & no guarantee what a remap would achieve. I suggest (nicely) just accept this is what you get with a 2.5 4Motion, & lot of other benefits too.
 

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Discussion Starter #6
You are getting good figures, are you using the onboard readings?
no i don't have such readings, these are real mpgs calculated every time I refuel.

And for info, i'm more often than not on the nun side of the driving spectrum, i already switched the fat 20' wheels for thinner (and much more comfortable!) 17' wheels, and i usually overpressurize the tyres a bit.

Anyways, thanks to all who replied. The consensus seems to be that my figures are not as bad as I thought, so i'll leave it as is for now rather than paying 300+ for nothing significant (best case) or for messing it up (worst case).
 

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As fenwick mentioned above, tuning for efficiency is the best thing for these motors, also fitting larger injectors and more efficient small, modern turbo's. Basically all them mods help improve engine volumetric efficiency and thus making better use of the limited amount of fuel injected per stroke. Thats why heavily modded diesel engines return similar or better Mpg than stock motors, however 1st law of thermodynamics states that what goes in must go out so if you use the available power all the time fuel consumption increase !

Best would be to drive the van in a more active way, DPF's and EGR valves do clog with your style of driving and sometimes even VNT mechanism on the turbocharger ! My advice is drive it and forget about max fuel economy, worry more about what will break with a sedate driving style...
 
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