legacycentral bbs

I'm going to school in Klamath Falls, which is around 4300ft. I've noticed a few things about how my car changes with the elevation:

1) When I romp on the gas, typically the car switches into 'power mode' and takes off. When in kfalls, this does not happen.

2) There is a weird buzzing/humming sound thats most noticeable around 2-3.5K (until the tranny shifts and the rpms drop). It changes with speed. Initially I thought it was some problem with my transmission (I'm pretty sure its slipping or something anyways), but this weekend I drove back to a sea level city and I don't hear the sound anymore (or it's still there just not really noticeable anymore).

3) The engine often revs up to 2K when in drive or reverse to get the car moving. Then all of a sudden, it engages and the car jerks in the direction. This a sign there are problems with the transmission? Yea, this isn't an elevation issue since it happens all the time. The transmission was swapped out with another 89K mile AT 2 weeks ago.

4) Obvious lack of power compared to sea level -- yea, I realize this is normal because of the elevation.

Are there some changes the ECU makes based on the MAP sensor or something? Forget who's the user here thats at 5000ft -- You notice any of these things?

Yo.

I've got an autotragic up here at 5000ft, that I've driven at sea level previously.

I can tell you that the tranny buzzing sounds are unfamiliar to me, no idea how that's related but... it sounds like you may be low on ATF if you've got to rev it up to 2k before it moves in D or R. Definately something I'd check before driving it more. Check with the car on, after moving the selector through the gears, and read the appropriate side of the dipstick (hot or cold).

I've noticed here that even at light throttle I will get Power mode when climbing a grade. I think it has to do with the ECU determining that you're not accelerating fast enough for the given throttle position, and it tries Power mode out and drops a gear.

You are also probably running a higher relative boost level - still using the stock boost control correct? At sea level you'll get about 9 psig, up here it's more like 11 or 12 to compensate for the lowered atmospheric pressure. The turbo's working harder and pumping out hotter air. Fuel cut will generally occur earlier at higher elevations, I know I had to set my FCD to clamp at 3.9V instead of 4.3V to avoid it up here.

Hope this helps, good luck!