[Cardiak]

Originally Posted by arpad_m

No need. First, the difference in air density between 630ft and 970ft is only ~3%, which is very easy to compensate for, and second, you are going from denser to thinner air, so if anything, your current tune will be safer and you'll lose a bit of performance.

It's when you have the car tuned to the max at, say, 8-9000 ft (thin air -> tune sets fuel volume for max performance -> perfect AFR) and then go down to sea level with the same tune that you have to watch out, because your fuel system may run out of capacity: as the ECM is trying to adjust (increase) the fuel volume to match the higher air density, it reaches the limit and can't go further because your hardware simply can't push more fuel, and your mixture leans out, potentially leading to engine damage.

Excellent. Thank you.