Here's what it says in Gadget's U-Tune:
What I take from this is that if you tune your maps for where you LIVE, the FTC, and ECU have enough of a capability to compensate for driving in other altitudes and be okay. But if you live at a higher elevation, or will be there for an extended period of time, and want the best performance from your Supercharger - you might want to adjust your maps, but it's not a neccessity.U-Tune by Gadget said:Altitude Changes:
The FTC has a feature that most of these programmable calibrators do not have. It has an internal Manifold Absolute Pressure (MAP) sensor that reads the manifold pressure. This makes the FTC much more expensive to produce, but the extra cost is worth it. As the ambient and weather conditions change you can make different levels of manifold pressure at the same throttle setting.
Keep in mind that the stock ECU and its Mass Air Flow Sensor (MAF) has very
powerful altitude correction capability. We are using the MAP sensor to tweak
this to our benefit. Using the MAF sensor and tweaking it with a MAP sensor onan engine converted to forced induction is the best way to do it.
The startup maps URD provides are done at sea level. The TRD Supercharger
will make around 6-7 PSI of boost at sea level with the stock pulley. If you go up in the mountains the boost produced will be less, much less. At around 5000 feet the supercharger will make only about 3 PSI of boost even if the boost gauge reads 6-7 PSI. The FTC reads absolute pressure calibrated to a true vacuum where the boost gauge reads a differential pressure comparing the manifold pressure to the air pressure outside of it.
What will happen is that the Wide Open Throttle (WOT) part of the fuel map will no longer be at 6-7 PSI, but will drop and drop as you climb higher in altitude. This allows you to tune your truck for best power at any elevation. It will not require a map change as you change altitudes after you finish tuning. So if you live at 5000 feet you can tune your vehicle for that elevation. When you come down to sea level you can tune that part of the map and do that for elevations in between. Once you have dialed it in for those changes in elevation, it is done and you should never need to retune it.
It is important that if you live at a high elevation you must retune the map for your location and remember the URD “startup” maps are done at sea level. They may be overly rich at higher elevations until your adjust that part of the map.