A very common question I have been asked many times over the years is whether there is a need to adjust fuel maps for elevation.

My answer to this question is very specific to Yamaha's late model FI ECUs on bikes like the VMax, R1, R6, Warrior, Liner or Raider.

We have tested the following bikes with maps done at sea level (in the bay area) and taken them up to about 11,000 ft elevation - enough to see what happens:

RS Warrior, Stratoliner and the all new VMax.

All of the bikes have been equipped with a Wideband Commander and an onboard realtime display for AF and Power Commander Data. That way the effects of elevation can be measured rather than guessed - by seat of the pants type science.

The tests where done without any onboard OEM O2 narrowband sensors hooked up, to get a precise measurement of how the ECU compensates for elevation changes.

All the bikes mentioned have in addition to the intake vacuum sensors and ambient air pressure sensor, that allows the ECU to correct elevation changes in real time.

Why is that important? When you climb a steep mountain like Sonora Pass in Northern/Central California, you climb the last 8000ft (or so) very quickly, without much cruising around. It is important for the ECU to constantly adjust to the new elevation, turn by turn, feet by feet.

The Yamaha ECU designers did a wonderful job making the ECU elevation aware. The exact same fuel mapping that is optimal at sealevel, works close to perfect all the way up to 11,000 ft elevation. And I mean nearly perfect: within 0.1 of the target AF ratio set for a specific rpm/throttle position. That's stock without any modifications.

When you add a Power Commander, you add or subtract % changes to the fuel delivery from the ECU. Turns out that these relative changes are linearly proportional to the elevation correction of the ECU.

Long story short: A custom map done at sea level, will perform just as good at 11,000 ft.

Having said that, don't expect you bike to make the same 190 rwhps at 11,000 ft. The lack of Oxygen in the much thiner air will cause the engine to loose substantial amounts of power - any normally aspirated engine will loose it. No magic around that. But the power that is delivered is spot on with the AF ratio programmed at sea level. Not too rich, not too lean.

So when you add a custom map to your bike or download one from the internet, elevation is the least of your issues. In fact its not an issue at all. A map done in Denver will work just fine at sea level.

However - every bike is different - we have seen this on virtually every bike we dyno. A custom map done for a particular bike will never fit another bike 100%. 

So when you download your next map, just keep in mind that your very own bike will be slightly off. Might be good enough or close enough, just be aware that a downloaded map will never be a perfect fit.