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Remapping diesels for better mpg

richardg

richardg

Admonishtrator
Does it work? My van is pretty poor, 2016 1.6 Vauxhall Combo with a rather elderly design Fiat diesel motor in it. I'm only getting 40 to the gallon on the computer dash readout. Id remap it if that jumped to 45. But 250 quid for what might be a snake oil service , I am dubious. Has anyone done it?
 
I haven't but have had good results adding Redex to the tank at each fill-up

Gives a few % more MPG and stops it sounding so much like a bus
 
I had a Golf gtd remapped from 170 to 200 ponies a few years back. More power, and more importantly more torque, theoretically means that you can get same pulling performance but on lower throttle openings.

In practice Cabot say I noticed, cos a 200 hp diesel was too tempting to boot and surprise the gti brigade.

Ran smoother though.
 
I did my Jag diesel 2.2 Manual. Wooomph - it was amazing. If your van is a Turbo you will probably see a benefit. I think most conversion places will remove the conversion if it does not do what they say, so what have you to lose?. I got a lot more power and better consumption too. My current Volvo even has an official remap available at dealers - bit pricy although I am still tempted.

Just have a proper one done though - DO NOT stick on a 'tuning box'.

I have noticed that some commercial vans from a big National chain (was it BT? not sure) had a sticker saying they had remapped for better economy.
 
Can map for economy or performance. Had my Mazda 6 2.2. done for performance but I think it helped the mpg too as I was doing 100m/day.
He did offer a specific map for economy but wasn't my main concern at that point.
 
I have a 2009 WV caddy, which is 104bhp standard. I had a cheap garage remap done - far from a proper fettling, but it was only £150. I can't remember the promised gains now, but I didn't believe them anyway and there was no rolling road... This was a couple of years ago.

It runs much smoother and quieter, and is much more responsive when heavily loaded. It used to do 39-40mpg, now it's 40-41mpg. Hardly earth shattering performance or economy gains, but it drives better.
 
Rich, is that 40mpg laden? If not that's pretty bad.

LWB transit connect 1.5 here, permanently 75-80% load capacity and it does 47mpg, down to 45 when it's warm and I leave the air con on all day. Down side is that it's slow as sh*t, verging on dangerously so in some situations. Must be a crap engine because the remappers only offer about 15bhp gain, which for a modern TDI is pretty poor.
 
Two thoughts on this Rich:

First, if you have a remap be careful with the clutch, or talk to the remaper about this issue, as the extra torque can be a bit much for a standard clutch.

Secondly, if its available, have you thought about using premium grade fuel as its benefits include cleaner fuel systems and higher cetane values both of which might help with your fuel consumption and smoother running.
 
matt j said:
Rich, is that 40mpg laden? If not that's pretty bad.

LWB transit connect 1.5 here, permanently 75-80% load capacity and it does 47mpg, down to 45 when it's warm and I leave the air con on all day. Down side is that it's slow as sh*t, verging on dangerously so in some situations. Must be a crap engine because the remappers only offer about 15bhp gain, which for a modern TDI is pretty poor.
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Empty and on a motorway run 45mpg if I keep it legal.
 
matt j said:
Blimey that is grim.
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I knew it was bad but was hopeful. I think the engine has been around for 20 years.
Unsurprisingly, all the remaps have been done for more power with not much of an eye on the mpg...You boy racers, you.
 
Snufkin said:
Two thoughts on this Rich:

First, if you have a remap be careful with the clutch, or talk to the remaper about this issue, as the extra torque can be a bit much for a standard clutch.

Secondly, if its available, have you thought about using premium grade fuel as its benefits include cleaner fuel systems and higher cetane values both of which might help with your fuel consumption and smoother running.
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Right but I was not expecting to be booting it, I'd rather it was slower. I am also hoping they will adjust the turbo to come on at lower revs. My logic tells me this will help mpg?
 
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Alan Brown said:
I have a 2009 WV caddy, which is 104bhp standard. I had a cheap garage remap done - far from a proper fettling, but it was only £150. I can't remember the promised gains now, but I didn't believe them anyway and there was no rolling road... This was a couple of years ago.

It runs much smoother and quieter, and is much more responsive when heavily loaded. It used to do 39-40mpg, now it's 40-41mpg. Hardly earth shattering performance or economy gains, but it drives better.
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i was hoping someone would say they got 10%
 
JensenHealey said:
I did my Jag diesel 2.2 Manual. Wooomph - it was amazing. If your van is a Turbo you will probably see a benefit. I think most conversion places will remove the conversion if it does not do what they say, so what have you to lose?. I got a lot more power and better consumption too. My current Volvo even has an official remap available at dealers - bit pricy although I am still tempted.

Just have a proper one done though - DO NOT stick on a 'tuning box'.

I have noticed that some commercial vans from a big National chain (was it BT? not sure) had a sticker saying they had remapped for better economy.
Click to expand...
10% better?
 
richgilb said:
Right but I was not expecting to be booting it, I'd rather it was slower. I am also hoping they will adjust the turbo to come on at lower revs. My logic tells me this will help mpg?
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It will already come in fairly soon, they can't really map-in boost threshold I don't think, that is governed by the exhaust housing size of the turbo and it will already be very small due to its application.

I think you're stuck with what you've got. MPG increases from remapping usually just come from more accurate tinkering with the fueling over the generic OEM map that has to suit a million engines and fuel qualities.
 
richgilb said:
Right but I was not expecting to be booting it, I'd rather it was slower. I am also hoping they will adjust the turbo to come on at lower revs. My logic tells me this will help mpg?
Click to expand...
Most of the remaps lower the degree of safety around the measures taken to deal with crap fuel, high altitude, etc. Not a problem in the UK. That's how they get better economy and performance at the same time.
 
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