cpd

Alright as quick as I can explain but still somewhat long... I just took my 1.8 from its home of New York City to Breckenridge/Blue River Colorado and had it up there for 8 weeks. The house was at 11,600 feet. The car ran well with a slight reduction in power as any combustion engine experiences with the thiness of the air. They only have 85,87 and 91 octane out there so I ran it on lower octanes then some of the 92,93,94's the car was used to. I had a couple services out there, A couple misfire codes had been stored and reset. Nothing major done.
I drove back to the east straight through, two days ago and upon arriving and ditching the gear, I was astonished at the power increase.
Now I've done this drive 15 times round trip in various cars(4's 6's and v-8's) and I understand that when you feel the lost power come back as you decend high altitude, the car seems faster, but thats in respect to it being so much slower. The change in the A4 goes beyond perception. My car has become much faster and throttle response has improved. I can bark the tires since I've come back and I was never able to do this before. It feels a lot more free to rev. I have 21,000 miles on it and I have not been in for the 20 thou service yet, the car is not chipped. I have driven a b6 chipped A4, not sure which one, but if I recall it was a nuespeed chip and my car feels about the same as that right now. I know it sounds strange but something happened... I know it can't last...how could this be?

mykel8

It's the high altitude, it really wreaks havoc on performance as the car is STARVED for air and such

Tsle

Actually, this is not as true for Turboed engines- the forced induction helps make up for thin air.

BMr Etr

Then again, it could be spontaneous vehicular chipping. I heard about this one time. This guy got into his car, and WHAM, it just chipped itself, just like that. Maybe it was the chip fairy. It could happen.