I have no idea what the technical reasons are, but there are definite gains in fuel mileage to be had after a remap. Plenty of us have found this

As an example.

When i was on holiday, i took it easy on the outward journey, not having driven on the "wrong" side of the road before.

I left home with the car on full (Optimax) and did the 325 miles to Dover, with 1/4 of a tank remaining.

I filled up again before boarding the Ferry to Boulogne, and i got 425 miles before the next fill-up, i would estimate there was another 20 miles left in the tank at this point, judging on past experience of where the true "empty" point is on the Octy fuel guage. I stuck to around 80 mph most of the way.

However....the return journey was somewhat different

140 mph on the Autobahn for a while meant 300 miles out of a tank :drive:

A good indicator is what I get out of a tank.....in standard form I use to get 425 miles...I now get anywhere between 320-380

my first tank of optimax i only got 360 miles! Is Ultima better for MPG?

my first tank of optimax i only got 360 miles! Is Ultima better for MPG?

Mine runs like a bag of spanners on Bee Pee.

Haven't tried it since the boost controller was fitted though.

I have no idea what the technical reasons are' date=' but there are definite gains in fuel mileage to be had after a remap. Plenty of us have found this

As an example.

When i was on holiday, i took it easy on the outward journey, not having driven on the "wrong" side of the road before.

I left home with the car on full (Optimax) and did the 325 miles to Dover, with 1/4 of a tank remaining.

I filled up again before boarding the Ferry to Boulogne, and i got 425 miles before the next fill-up, i would estimate there was another 20 miles left in the tank at this point, judging on past experience of where the true "empty" point is on the Octy fuel guage. I stuck to around 80 mph most of the way.

However....the return journey was somewhat different

140 mph on the Autobahn for a while meant 300 miles out of a tank :drive:[/quote']

This could be due to gradiants in the road.

To explain this, you drive down a hill and get 50mpg you drive up it and get 25mpg as you need more fuel to get up the hill. Same distance different gradiants.

I have started another thread for this discussion of remap MPG etc http://www.briskoda.net/forums/showthread.php?t=15484

But you need more fuel to push the turbo to create more boost surely ?

OK, this might be nonsense but it's a possible theory...

The turbo runs at higher pressures - this is controlled by the ECU, which doesn't release the wastegate as soon as the pre-remap version does. This in turn allows for a higher pressure air charge to be used, hence you get more power per bang...

Though if it's keeping the fuel-air mix ratio the same, then it would use more fuel... :rubchin:

Though in diesels you don't have a fuel-air mix... :rubchin:

Rob.

Yer Rob I thought about running higher pressure but the O2 sensor will increase the amount of fuel into the engine when the O2 goes up (More boost) so it cancels itself out. For a given amount of air (Boost) you have to have a given amount fuel (Petrol).

Rob don't know if I read it wrong but the wastegate don't hold the pressue it's the actuator that regulates the pressure in the turbo. The wastgate realeases the pressure when you shut the throttle off before the turbo. As soon as the turbo reachs max boost pressure the actuator regulates it and that presure.

Still foxing me.

Newquay to Thelwall one tank to light.

Gradients?

Ok then.

Hartlepool to NEC Birmingham. 190 miles (Tank full at start)

Return journey, same route, same mileage.

Total mileage- 380 with fuel to spare.

2 way journey cancels out any downhill "advantage".

Gradients?

Ok then.

Hartlepool to NEC Birmingham. 190 miles (Tank full at start)

Return journey' date=' same route, same mileage.

Total mileage- 380 with fuel to spare.

2 way journey cancels out any downhill "advantage". [/quote']

No to get a proper reading it needs to be perfecty flat, remember any gradiant is still a gradient, if you overtake cars you will also use more fuel. It's not as simple as just driving the car as there are lots of variable like wind direction, ambient temp, traffic density etc etc. :P

Well sorry, but perfect conditions are impossible.

Until then, all we can do is compare figures gained in "real world" driving, which have shown consistently that with reasonably restrained driving, a re-mapped car can produce better fuel mileage.

Well sorry' date=' but perfect conditions are impossible.

Until then, all we can do is compare figures gained in "real world" driving, which have shown consistently that with reasonably restrained driving, a re-mapped car can produce better fuel mileage. [/quote']

But "Real world" I think also says a remap will never have better MPG than a standard car as my points in http://www.briskoda.net/forums/showthread.php?t=15484

I am not starting any arguements but until someone can come up with a reason why the remap will be produce better MPG figures than the non remap and get everyone to say Ah yes NOW THAT MAKE SENSE I still maintain that the remap will be = < the MPG on a standard car.

It's not an argument, but there's plenty of us who have seen improvements.

As i said, i have no idea what the reasons are, and i wouldn't even begin to speculate.

However i do know that there are improvements to be had, as long as you drive with a reasonably light right foot.

It's not an argument' date=' but there's plenty of us who have seen improvements.

As i said, i have no idea what the reasons are, and i wouldn't even begin to speculate.

[b']However i do know that there are improvements to be had, as long as you drive with a reasonably light right foot.[/b]

OK let me try and approach this another way which will let you into the way I am thinking.

Car A = Standard at 70mph = 3/4 throttle

Car B = Remapped at 70 mph = 1/2 throttle

Remap = more fuel + high boost pressure which in turn means less throttle.

See where I am coming from. There is No way a remap based on these parameters can give better MPG's unless there is one vital fact I am missing which I would like someone to tell me PLEASE !!!! I am really struggling on comprehending why this WOULD give better MPG ! :confused:

OK if the remap effected the efficiency of the gearbox then I could understand it but it don't.

I guess we could test it in mine as I have the very usefull switching software, between

Normal, very close to original boost/timing

95 Boost about 207Bhp

98 Boost about 220Bhp

And no boost atall and that is slow.

As to "lab conditions" going to struggle unless you do it on a motorway at night. Same pump and person filling.

Problem is diesel tuning is add more fuel, petrol is a little more complex I don't fully undertand it, but for example I can adjust the timing alone, not fuel pressure or boost and it produces more power. Does it just more fuel I don't know.

Might try the above somehow over the next week, traffic being the worst problem.

Yer tis ner on impossible for lab conditions. Type of fuel may help but again there are other factors you need to take into account like 98 ron fuel is less likely to detonate thus allowing you to run more boost... more boost means more fuel so again I am not 100% convinced.

Be good to get some figures but alais due to variables as mentioned these would be vague at best.

see the other thread... that is also as long as a piece of string....

variable on the move maps are the only answer:thumbup:

Yep replied.. The first comment that makes sense.