The MK6 Fuel Consumption (Most / Least per Tank) Thread

[hooba]

Apparently it does....

If you did use less fuel, wouldn't that defeat the purpose of doing the Stage 1 tune?

[brad]

If you did use less fuel, wouldn't that defeat the purpose of doing the Stage 1 tune?

If people used 100% throttle more often then a tune wouldn't be needed by most people.

I avg 6.7L/100km in the Skoda with remap. Rarely put the boot in. I like the tune because it made the car much more driveable, not for the peak power it gave. Yes, I'm odd.

[SilvrFoxX]

Hey Brad, wouldn't that mean that a sprint booster would have solved your driving requirement over a remap.?

[Brian916]

Would a stage 1 tune lower fuel consumption?

Until I see proper laboratory testing, I will always remain sceptical about the claims of improved fuel efficiency. The simplest rule is that for more power you need three things: More air, more fuel and more rpm. Putting more fuel in needs more air to burn properly so more throttle is needed.

Where the equation WILL come back in favour of the remap is where the standard map is set very lean for the pollution factor. If you put less fuel in with the air, and make it just burn, you have less pollutants emitted. This also has a negative effect on power and economy. Problem is in most cases that this point is NOT at an rpm where the car cruises. For some reason it was decided that the test would be a simpulated drive by at a set speed/rpm. All the manufacture does is lean out the map for that point and they pass the emission tests.

By addind fuel to bring the ratio to the right level for economy - around 13.6:1 for an air cooled V twin (have to use the one I"m most familiar with) you get better economy as the engine is not under as much load. On the bike, I can use less throttle opening to keep the rpm at the sweet spot and use less agressive movement to maintain the speed I want.

I guess the easiest way to look at it for a car with a remap is simply to look at the factory tested figures for the higher output engines. The 155 motor has an 'average' of 7.9l/100km and the 188 is higher for the same test.

So, until somebody gets a car and puts it through the Australian standard test, then flashes the ecu and reruns the same test in the same car, I'm going to be a sceptic about the claims.

You can sort of approximate these tests yourself by NOT flashing the ecu until you've done your own tests. Let the car get around 5000km on it, then drive for several tanks of fuel in the most economical manner you can, trickle fill the car each time so you can't get any more fuel in, then work out the mileage. When you have done that, flash the ecu and do he same test - you'll have to be very diciplined. Compare the results and see if you get better or worse. Also take note of what the trip computer tells you. Most add on boxes will appear to give better consumptions as they change the signals AFTER the trip computer has got it's readings so it lies. Some trip computers are calibrated specificall for the factory map, and if you change that, it doesn't change what the computer was told to use as values and it will still lie to you.

I have had chips/remaps on a couple of diesels now, and have enjoyed the change in how the vehicles drive. Being diesel, the changes were done at 25000km (just on run in for a common rail engine), and doing the carefule trickle fill to GPS mileage, they were both less economical - in the case of the Astra, by a whole 1mpg average worse, and 1.5 in the 4wd.

When the lease is up on the Golf, if I decide to keep it, it WILL be getting an ecu upgrade, so I'm not against these remaps, just very sceptical about claims of improved economy.

[Corey_R]

In both my previous cars, the MKV Golf GTI and the 9N3 Polo GTI there were fuel savings with Stage 1. Significant savings with the Polo. Cause it has a K03 and has so much "driveability" down load with the tune, you never needed to put your foot down to get moving. (So SilvrFoxX, no a sprint booster instead of a stage 1 won't help, as effectively you'd always be putting your foot down, but getting less power and using more fuel).

There are so many guys with the Polo GTI and Stage 1 who have seen fuel savings within a few weeks of having it (not in the first weeks cause you're having too much fun). Best of all, you could switch back and forth between Stage 1 and Stock on that car and compare. With the Stage 1 I would constantly beat the VW fuel consumption rating, whilst still having my fun.


What about the Golf R?
I don't know... I didn't have the Stage 1 for long enough, and it's not switchable. I also had the Stage 1 at about 1500km, at which point the engine is still bedding in and fuel consumption is dropping anyway. So I never really got the opportunity to do any economy runs/tests etc.

[AdamD]

Where the equation WILL come back in favour of the remap is where the standard map is set very lean for the pollution factor.

Conversely, a stock tune may in fact run richer under certain circumstances. Many Japanese cars run notoriously rich under power (and can blow smoke from the unburnt fuel) in order to play it safe: a richer mixture with excess fuel will cool the engine internals; a car that runs too lean can generate too much heat and damage the internals.

[prise]

You would not run an engine lean to reduce pollution as it would produce increased levels of NOX. The best mixture for pollution reduction is stoichiometric (lambda of 1). Either richer or leaner than that and the catalytic converter effectiveness drops dramatically. Best power is normally made a bit richer than stoichiometric (lambda of 0.9) and best economy a bit leaner (lambda > 1). The only reason to run lean is to improve fuel economy.

Unfortunately, the only practical way to run lean AND meet the pollution regs is to use a special catalytic converter that can store the NOX produced when running lean and covert it later when conditions are more favourable. These special catalysts are poisoned by sulphur in the fuel so until Australia drops fuel sulphur below 5ppm we wont see this technology here. Current VW TSI engines sold in Aus DO NO run lean burn - they run a stoichiometric mixture over most of the operating range with a richer mixture at high power conditions to increase power and keep temperatures down.

I'm also very skeptical about reflashes improving economy under normal driving conditions for the folloiwing reasons:

a) The manufacturer invests millions on calibration and validation to ensure they get the best economy they can compatible withe meeting emissions regs and durability targets. Getting a lower number on that fuel economy sticker is important to them.

b) Economy in normal driving is all about efficiency at part load, and low to mid rpm. At these conditions the stock tune has to run stoichiometric to meet emissions. If an aftermarket tune was leaning it out at these conditions it would be at the expense of increased NOX emissions.

You could get better efficiency at high power conditions as these are not tested as part of the ADR test cycle, but only by leaning it out which will reduce component life (cat, turbo, valves, etc)

[brad]

Hey Brad, wouldn't that mean that a sprint booster would have solved your driving requirement over a remap.?

Nope.
I like my torque curves to be shaped like half an egg rather than a mesa.

[SilvrFoxX]

Nope.
I like my torque curves to be shaped like half an egg rather than a mesa.

Just like your women?

[brad]

Just like your women?

No, I like my women to be black, sugary & instant. No, wait, that's my coffee.

I think Humpty Dumpty likes his women to be egg shaped.