Testdr
Active Member
- Joined
- November 15, 2007
- Messages
- 59
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- City, State
- Reading,Pa
- Year, Model & Trim Level
- 03 LIMTED 03 PREMIER
I been wondering & searching for weeks now, so please don´t burn me.
Well... I have posted about this before, so as u may know I been on a 3 month expedition with my 2003 Limted V8 4x4 (creamic white, my favorite color) anyways... I´ve been threw some of the harshest enviroment down here in southwest Mexico, that I´m surprised how cars last so long?
Speedbumps everywhere, potholes worst then jersey & nyc combined!
. And 2 tell u the truth my truck is holding up pretty good, except for a bad fan clutch & a ripped o2 sensor wire WHICH WAS ACTUALLY REPAIRED INSTEAD OF REPLACED! (Talk about craftsmanship)
Now to the reason for this thread... Where I´ve been staying, It´s about 7,800 ft above sea level, and the tranny has had trouble understanding that.
What has been happening is that I been expirencing hard ****ing after about 30 mins of driving in high altitude, which has been happening ever since I started to ascend into high altitude, Now... I tested the truck at several times & different sea levels & what I´ve come up with is that at sea level (which was at Puerto Villarta 0 ft above sea level) I drove the truck hard for several hours trying to heat up the tranny fluid & trying 2 get it to do the hard shifts (thats the reason the fan clutch went too) & guess what? NOTHING! not 2 mention it also gained power from there being more o2 at sea level & the higher altitude gas as well. It performed great w/ no signs of any hard shifting (shifted like butter). And this was not a 1 time occurence either, as I have gone to beach (sea level) again recently & the same great performence again. Now when I come back home is when the hard shifting begins(back to high altitude) WHY?
THEORY:What I´ve been reading is that shift points are in 1 part controled by throttle response, which would be affected because there is more throttle because of the climbing & the higher the altitude the less o2 in the air which would cause a vacuum indifference fooling the truck into thinking it´s operating at a faster speed, causing the shifts to firm up, which naturally cause´s the tranny fluid 2 heat up in time, which has happen 4 times before already, so yes I know that I´m due for a tranny fluid change soon.
but this problem is not going to go alway w/ just the fluid change, it´s more then likely going to burn the fluid again because of the incorrect vacuum pressure causing the hard shifting.(not 2 mention I already got the tranny flushed at 55k & now has 65k)
From what I read is that eletric & hydralic trannys use VACUUM MODULATORS, but have heard that the 55r5w are eletronically controled & don´t use vacuum modulators which brings me to another question? There are vehicles that use special vacuum modulators that compensate for higher altitudes what would be the same fix in a 5r55w? Or is it reprogramable w/ a pcm update?
Sorry for the long post. & any knowedge towards this would be greatly appreciated. THANX
Well... I have posted about this before, so as u may know I been on a 3 month expedition with my 2003 Limted V8 4x4 (creamic white, my favorite color) anyways... I´ve been threw some of the harshest enviroment down here in southwest Mexico, that I´m surprised how cars last so long?
Speedbumps everywhere, potholes worst then jersey & nyc combined!
. And 2 tell u the truth my truck is holding up pretty good, except for a bad fan clutch & a ripped o2 sensor wire WHICH WAS ACTUALLY REPAIRED INSTEAD OF REPLACED! (Talk about craftsmanship)Now to the reason for this thread... Where I´ve been staying, It´s about 7,800 ft above sea level, and the tranny has had trouble understanding that.
What has been happening is that I been expirencing hard ****ing after about 30 mins of driving in high altitude, which has been happening ever since I started to ascend into high altitude, Now... I tested the truck at several times & different sea levels & what I´ve come up with is that at sea level (which was at Puerto Villarta 0 ft above sea level) I drove the truck hard for several hours trying to heat up the tranny fluid & trying 2 get it to do the hard shifts (thats the reason the fan clutch went too) & guess what? NOTHING! not 2 mention it also gained power from there being more o2 at sea level & the higher altitude gas as well. It performed great w/ no signs of any hard shifting (shifted like butter). And this was not a 1 time occurence either, as I have gone to beach (sea level) again recently & the same great performence again. Now when I come back home is when the hard shifting begins(back to high altitude) WHY?
THEORY:What I´ve been reading is that shift points are in 1 part controled by throttle response, which would be affected because there is more throttle because of the climbing & the higher the altitude the less o2 in the air which would cause a vacuum indifference fooling the truck into thinking it´s operating at a faster speed, causing the shifts to firm up, which naturally cause´s the tranny fluid 2 heat up in time, which has happen 4 times before already, so yes I know that I´m due for a tranny fluid change soon.
but this problem is not going to go alway w/ just the fluid change, it´s more then likely going to burn the fluid again because of the incorrect vacuum pressure causing the hard shifting.(not 2 mention I already got the tranny flushed at 55k & now has 65k)
From what I read is that eletric & hydralic trannys use VACUUM MODULATORS, but have heard that the 55r5w are eletronically controled & don´t use vacuum modulators which brings me to another question? There are vehicles that use special vacuum modulators that compensate for higher altitudes what would be the same fix in a 5r55w? Or is it reprogramable w/ a pcm update?
Sorry for the long post. & any knowedge towards this would be greatly appreciated. THANX
