Long time since been on here. I have an issue that I have noticed for a few years now, and this weekend really bugged me.
It appears I loose power at Altitude.
I live at +600m (~2000ft) ASL, and work at +50m ASL, and whenever I visit the high country which is starting at +1500->1860m (4900->6000ft) ASL, I start to notice the power issues.
The symptoms are; accelerating through 2nd, 3rd, i'll get what feels like "mis-fires" or micro steps in power, or where the revs momentarily hold revs then continue to climb. Generally speaking while flicking through the corners, it gets your attention but it's gone as quick as it appears. For the last 4-5years i've been noticing it, it hasn't really bothered me, and each time I put it down to spark plugs, or something else.
This weekend, I noticed it more attempting a wheelie for a photo op.
On initial take off from stationary, it was obvious to me the bike just wasn't lurching forward like usual. Attempting the wheelie itself (power-ups), the front never lifted. Several attempts and my mates bagging me out, I resigned.
Next day, also hot, back at lower Altitude, straight up no issues.
My only thought is a defective oxy sensor that isn't throwing an error code?
Does anyone have any experience with this?
Bike; '08 Daytona, only mods are the intake flap permanently opened (pipe blocked).
Power loss at altitude is inevitable and universal across all internal combustion engines. No matter how many sensors and adaptations from the ECU.
The higher you go the thinner the air gets and what it boils down to is less and less oxygen available for combustion.
The same happens when comparing power in cold weather vs summer heat. Same principle.
Yes, modern engines have all kinds of sensors and adaptations for that. But all this does is slightly adjust the air fuel ratio according to sensor input. Adjusted AFR means that the combustion is still as EFFICIENT as possible given the available conditions (air pressure, temperature etc...), and does NOT mean that the loss of power will be completely compensated for. Just minimized a little if at all.
It is important to understand that these adaptations will help the fueling of the engine to keep it running smoothly and efficiently as opposed to running rich, so the actual ECU adaptation end point in this case will be to send less fuel to the engine to keep a steady AFR.
So in the end the engine is getting less air and less fuel in the same ratio, leading to a significant and noticeable power loss. There is nothing you can do about it short of using an oxidizer like NOS.
If there’s no sputtering or abrupt power loss at a given rpm or throttle position, your problem is a simple manifestation of physics.
A sensor problem or air leak will manifest itself at any altitude. Also bad sensors usually trigger a CEL.
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