Hi All;

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).

ta

I know the 13+ Daytona have a barometric pressure sensor under the front head fairings, however not sure about the first generations. I would start there

They all have baro sensors.

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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Great write up, thanks very much!

If I were to check the sensor parameters, what is a healthy voltage range on the Barometeric sensor? Last night I connected the Android TuneECU app (via wired OBD2 connector) and the baro pressure was extremely high at around 1200 hPa. I expected it to be around 1000 hPa given the weather and reading off my watch (has baro).


For anyone with experience with the TuneECU app, the "Barometric Pressure" (measured in hPa) and "Atmospheric Pressure Sensor Voltage" (measured in volts) are the same sensor yes?

thanks all

Hi All;

More info, spoke to a friend who is rather gifted with this stuff.

Given that my air pressure sensor is well over reading (1240pHa at what should be 1010pHa), he said this will be running the bike at it's richest map. This is confirmed with reading the map, and it's highest allowance for pressure is 1013.

Meaning when I get to altitude, it's well over-rich and loosing power.

So my next question, where is the Atmosphere Pressure sensor on a Daytona? I know the MAP sensor is connected to the clean side of the airbox.

ta thanks

On the 13+ I believe it is just under the headlight

I should clarify that it is not a part of the intake. It just looks like a small tube that sticks out the bottom of the front fairing under the headlight. It is easy to miss the connection on if you ever take the fairings off. I am not sure but it could default to a rich setting if it is disconnected but it would throw a check engine light.

So I removed the mirrors and screen tonight, and with a little stuffing around you can remove the sensor.

Applying light vacuum and pressure to the sensor had very little effect on the reading on TuneECU.

I decided to remove the tank to test the wiring to the ECU. What a mistake that was................. more on that later.

The wiring has continuity to the ECU, and no shorts to anywhere else. So my conclusion is the sensor is stuffed. I am going to see if I can get one from a wreckers just to see if the value read on TuneECU changes, then go from there. They are $180 AUD.


Under the tank however, I noticed the plug between the stator and rectify-regulator is absolutely cooking. Plug itself is all melted, and the wiring is burst to ash. I'm surprised it's still functioning. I've already had that stator re-wound, and the reg-rec done on the recall.

Going to see what I can't salvage on the weekend.

Same principle