NefMoto

I'm driving from Nashville to Indianapolis this weekend and wonder what would be some easy things to change to get high miles per gallon.  lower the requested boost and lean it out a to what? I know I control a lot of that with my right foot, but I have a heavy right foot :-)

If it is just your foot, adjust the pedal map  ::) I would not suggest to run lean, especially on a long trip! You could lower the requested torque too, but dont mess with afr.

You need to lean out the file to get real mileage improvements. Anything else you can do on a stock file with good driving.

I like the pedal map idea. and that's 1 vote for not running lean and one vote for running lean.  anyone else?

I'm not sure if the ECU can support lean, why not go try it?  Like, I'm sure I read somewhere that stoich is it's max limit, might be wrong though.

So, if it's not, recalibrate the tables of Lamda and under 50% load, make it lean, to the point of 16ish AFR.

Monitor EGT's carefully and you might be able to squeeze in a little more timing. 

You can't request leaner than stoich. Even if you could, these are narrowband cars.

Maybe one could adjust open loop to run lean and unplug the 02sensor  ??? lol
In my advice I consider "lean" to be leaner than stoich offcourse. I think you can better pay for the extra gas in your tank, if you can't afford driving it, don't  ;D

Meh, good advice I guess but I just dig the feeling of being effecient from time to time

Not really into the ME's, but on Trionic i've gained quite some with only adjusting ignition advance. 1 or 2 deg can make already quite some difference. But watch out for knocks when on petrol, and too high PCP when on E85.


Regarding running lean. A no go if you are running a cat but if possible (again i'm coming from trionic...) restrict closed loop to something like stationairy only. And have open loop, on cruise, aim for 17:1 or so.

But only attempt this if you have wbl and egt... otherwise it can become more expensive than all the gas/E85 you will ever save ;)

I never saw what cars were mentioned in this thread, why did you say they are narrowband? Also as in "you can't request leaner than stoich" what versions of ME does this statement apply to?

The original poster has a 2.7t. All 2.7t are narrowband.


All of them.

Thanks for clearing that up, D!

+1 that's useful to know.

I'm having a hard time wrapping my head around this statement that all versions of Motronic up to the latest direct injection MED17 can't request leaner than stoich. As elegant and over engineered an engine management system ME is this comes as a big surprise. Can you elaborate a little more, on why it isn't done, or possibly not possible?

They cheaped out and stuck with a narrow band design, and the wideband code is SYSDEF'd out in all of the 2.7t binaries.

Ok, maybe I misunderstood D's response. I asked which versions of ME he was referring too, and he responded "all of them". I suppose he was referring to just the 2.7T's? Thanks, Nyet.

Nope, you understood correctly. You cannot request leaner than 14.7 on any ME7 (that I am aware of, I have been wrong before) without hacks.

Whoa? Even wideband ME7? I did not know that.

What about 9 and 17?

Press release for the FSI: "The North American-spec 2.0L FSI Turbo engine should not be confused with the similar European-spec FSI powerplant, which features a third mode of engine operation, stratified charge combustion, to allow short periods of extremely lean burn. In such low-speed, light throttle conditions, the very slight amount of fuel added to the mixture can result in stoichometric ratios as high as 65:1 (the normal ratio for gasoline engines is 14.7:1) and periods of exceptional fuel mileage. Because of North America’s lower fuel quality (which would require special catalysts to handle the extra NOx emissions from our high-sulfur-content gasoline), this technology is not yet available outside of Europe. True stratified combustion will be integrated into this engine, and other VW (and Audi) FSI powerplants, when the high sulfur content of U.S. fuels is decreased in the next several years."


AFAIK they dropped this idea for emissions reasons before / very shortly after release of the AXX.

Great info

Yea but dont think you get away with this in your non-DI engine ::)

That's very cool! Tfsi conversion next maybe

http://www.intechopen.com/download/pdf/43668

The paper in the link describes stratified charge combustion under different conditions in a test motor. I wonder what kind of fuel economy you can get with this?