High altitude power loss?
Question:
My truck is tuned for sea level operation. I go camping several times a year in the mountain areas above 5000 feet+. I notice a significant loss of power at about 3000 feet and up. I understand that this is normal and that things need to be adjusted to get better, but never as good as sea level, power output. Is there a simple – temporary – adjustment that can be done ? Air fuel mixture etc. or is the tune-up more involved? I think the engine control computer is supposed to compensate for changes in altitude, but I am not sure if it was designed to do that big of a change without human intervention. Maybe my unit is malfunctioning? Is there an after market controller that would allow me to flip a switch or something for high altitude operation? My truck is an 86 F150 4×4, EFI 302cid (5.0l) V8, K&N air filter. Flowmaster (3 stage) muffler etc. Thanks Kevin Kevin Ricks
Response:
]My truck is tuned for sea level operation. I go camping several times a ]year in the mountain areas above 5000 feet+. I notice a significant loss ]of power at about 3000 feet and up. I understand that this is normal and ]that things need to be adjusted to get better, but never as good as sea ]level, power output. Is there a simple – temporary – adjustment that can ]be done ? Air fuel mixture etc. or is the tune-up more involved? I think ]the engine control computer is supposed to compensate for changes in ]altitude, but I am not sure if it was designed to do that big of a ]change without human intervention. Maybe my unit is malfunctioning? Is ]there an after market controller that would allow me to flip a switch or ]something for high altitude operation? My truck is an 86 F150 4×4, EFI ]302cid (5.0l) V8, K&N air filter. Flowmaster (3 stage) muffler etc. Advance your timing, or use lower octane fuel. If you advance your timing, don’t over-do it. If it pings, then you went too far. Kevin Tapperson
Response:
- Hide quoted text — Show quoted text – My truck is tuned for sea level operation. I go camping several times a year in the mountain areas above 5000 feet+. I notice a significant loss of power at about 3000 feet and up. I understand that this is normal and that things need to be adjusted to get better, but never as good as sea level, power output. Is there a simple – temporary – adjustment that can be done ? Air fuel mixture etc. or is the tune-up more involved? I think the engine control computer is supposed to compensate for changes in altitude, but I am not sure if it was designed to do that big of a change without human intervention. Maybe my unit is malfunctioning? Is there an after market controller that would allow me to flip a switch or something for high altitude operation? My truck is an 86 F150 4×4, EFI 302cid (5.0l) V8, K&N air filter. Flowmaster (3 stage) muffler etc. Thanks Kevin
Boy, you should feel the difference at 10,000 feet! As you climb higher, the air becomes less dense, hence your effective compression decreases and your fuel/air mixture becomes more rich (same gas, less air). Therefore, you can advance your timing (I go 2-4 degrees here) and lean out the fuel mixture. You will get some back, but not all of it. It should go without saying that you MUST readjust before going home as a leaned out/advanced engine could experience some expensive problems if worked too hard. Your computer may make some fuel adjustment, but I doubt that it will advance your timing for you to make up for the lower effective compression. Of course, this is offset by being able to drive faster because of the lesser air resistance. 8^) Dale Anderson Boulder, Colorado
Response:
: writes:
: My truck is tuned for sea level operation. I go camping several times a : year in the mountain areas above 5000 feet+. I notice a significant loss : of power at about 3000 feet and up. I understand that this is normal and : that things need to be adjusted to get better, but never as good as sea : level, power output. Is there a simple – temporary – adjustment that can : be done ? Air fuel mixture etc. or is the tune-up more involved? I think : the engine control computer is supposed to compensate for changes in : altitude, but I am not sure if it was designed to do that big of a : change without human intervention. Maybe my unit is malfunctioning? Is : there an after market controller that would allow me to flip a switch or : something for high altitude operation? My truck is an 86 F150 4×4, EFI : 302cid (5.0l) V8, K&N air filter. Flowmaster (3 stage) muffler etc. I have a friend who had a ‘54 Dodge Power Wagon that he used to go from Death Valley to the White Mountains. (I live in California). He needed all of the output he could get from the old flat head six in his truck. At the advice of a friend, he installed an "altitude control valve". He got a brass needle valve, and soldered it to a plate of metal that he could screw under the dash. He ran a piece of rubber tubing between the valve and the intake manifold. He lived at sea level (San Diego), and his truck was tuned to run there. When he went up into the mountains, he would open the needle valve a bit when he noticed the performance of his engine was beginning to drop off. This leaned the mixture out by adding air to compensate for the carburetor that was running too rich, being set at sea level. I rode with him on several occasions, and the extra air made a noticeable difference. You might try his trick. On the other hand, if you have a computer controlled fuel system, the computer will probably notice the leaner mixture, and adjust the fuel flow to compensate. You will have to experiment a bit and see if this trick works for you. Good Luck- —
