7000 ft up
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Mountain Pass
Joined: Sep 2004
Posts: 140
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7000 ft up
Hey guys. I have a 99 b3000. I took it up the tallest mountain in Hawaii. From about 7000 feet i started to loose power. then it just got worse the further i went up. A hill i could usually go up in 2nd or 3rd i had to go down to 1st and i couldnt shift to second.
Posting Guru
Joined: Dec 2003
Posts: 1,651
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From: Maine
On a '99, it would all be controlled by the computer. If you lived at 7000 ft, it would eventually recalibrate itself, or disconnecting the battery should do it.
But, don't expect it to run at that altitude like it does at sea level. It won't. I drove my father's Focus through Colorado (highest pass I drove over was 12,000'). The computer was reset in Denver (due to a breakdown
), and I didn't notice that I regained any of the performance I had lost from lower altitudes. I eventually found that at altitudes over 6500', I just had to rev the car (manual trans) more than I am used to to get the same amount of power. Once I got used to doing that, I didn't have much trouble.
But, don't expect it to run at that altitude like it does at sea level. It won't. I drove my father's Focus through Colorado (highest pass I drove over was 12,000'). The computer was reset in Denver (due to a breakdown
), and I didn't notice that I regained any of the performance I had lost from lower altitudes. I eventually found that at altitudes over 6500', I just had to rev the car (manual trans) more than I am used to to get the same amount of power. Once I got used to doing that, I didn't have much trouble.
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Mountain Pass
Joined: Sep 2004
Posts: 140
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ok im confused. so should have or shouldnt have the computer compensated? Beacuse i went up from 7000 to 9300 ft let the truck idle there for about 15 min then shut it down for another 15 then continued up the hill. It was a pretty rapid acent (7000-9300ft in 15-20min then 9300-12000ft in 20-30min) do you think the computer couldnt adjust that quickly. Another thought i had was about how exactly the computer adjusts for lack of oxygen. Does it run the mixture more rich? does it make sense that i had less compression braking on the decent as well? i pretty much came back down in 4Lo 3rd gear with my hubs unlocked and i still had to use my brakes to keep it from topping out my tach. I plant to do this trip again within a few weeks so if things can be tweaked to make the drive less hazardous to my truck im willing to try something.
i.e.: disconnect battery at 9300ft level for 5min to reset the computer?
i.e.: disconnect battery at 9300ft level for 5min to reset the computer?
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Posting Guru
Joined: Dec 2003
Posts: 1,651
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From: Maine
Disregard what I said, Bill knows these things better than I.
You're truck is fine, no need to disconnect battery.
You're truck is fine, no need to disconnect battery.
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Mountain Pass
Joined: Sep 2004
Posts: 140
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ok so its perfectly normal. thats good i guess. now can you recomend some driving tips? i dont think its the best thing for me to drive up in 1st gear all the way like the first time but i cant shift to second. should i use 4lo and go 3rd-4th? ohh and btw does my signature show? i cant get it to show on my screen on any of my posts.
Senior User
Joined: Jul 2004
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Loss of power at high elevations is normal. It isn't lack of oxygen, but the lack of air. The barometric pressure is lower, amount of air going into the cylinders is less. What you are experiencing is the opposite of forced induction.
Forced induction pushes more air into the cylinders. More air = more power.
High elevations result in less air in the cylinders. Less air = less power.
Modern computerized fuel injected engines will calibrate the air/fuel mixture as you change elevation, so you no longer have that problem with the engine running rich at high elevations.
For reference, air pressure at sea level is close to 14.7 pounds per square inch. At 7000 feet the pressure is around 10.9 pounds per square inch.
I guess the positive side to this is high elevations will cure those persistent pinging problems.
Forced induction pushes more air into the cylinders. More air = more power.
High elevations result in less air in the cylinders. Less air = less power.
Modern computerized fuel injected engines will calibrate the air/fuel mixture as you change elevation, so you no longer have that problem with the engine running rich at high elevations.
For reference, air pressure at sea level is close to 14.7 pounds per square inch. At 7000 feet the pressure is around 10.9 pounds per square inch.
I guess the positive side to this is high elevations will cure those persistent pinging problems.
Cargo Master
Joined: May 2001
Posts: 3,208
Likes: 13
read this post it pretty well explains it
https://www.ford-trucks.com/forums/s...3&goto=newpost
https://www.ford-trucks.com/forums/s...3&goto=newpost
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
Yup, like that thread correctly notes there's not as much oxygen at high elevations as compared to sea level. Remember, air is roughly 80% nitrogen and 20% oxygen. Electronic engine management systems compenstate virtually instantiously when driving; early GM's (early 80's) calculated the correct amount of fuel to apply to a given set of conditions 10 times per second. Today it's at least twice as frequent thanks to better microprocessors.