Hey

I'm not happy with the surging of my XT660Z. I have an OTR Exhaust. I made some travels and before i started i put a foam air filter in it and removed the snorkel. The power and unfortunately the surging got more. On my way, my intake air temperature sensor broke. So I replaced it with an used one. But now the surging is even more because it seems like the sensor is at the edge of the tolerance. Now I'm not sure what is the best solution to get a proper fix. Is the Kev O2 eliminator and the Kev fuel mod enough?

I saw that the disadvantages are that the Kev Mod is not temperature resisting ( http://www.xt660.com/showthread.php?p=203157). Which is a little bit a problem when u travel through different countries where the temperature can easily go from 5 to 40 Degrees within days or even hours.

But the bigger problem I see is with the eliminating of O2 sensor. It wont measure the O2 anymore. When i go up to 4000m above sea level is the engine still running fine? Which effect does the altitude gain have?
I saw that Dynojet is selling the Autotune kit with the Powercommander which should measure the intake air and adjust the A/F to the altitude. Is this the only solution to fix it?

I'm also concerned because when u go up to several 1000 meters above sea level. Both the air temperature and the pressure significantly change.
Do I maybe over react and the effects are not that significant? I would love to have a good solution but the 450 US Dollars for a Powercommander with a Autotune kit are quite expensive.

And I saw that i can also change a little bit the AF with the diagnostic tool. Is it fine to combine this with the Kev mod or the Powercommander?

It should be if everything else is working properly. A Power Commander will do a more accurate, tunable job taking into consideration revs, throttle position etc. (especially with a custom map), but ultimately a Kev mod and O2 controller will serve you well enough.

You shouldn't need to adjust it much, maybe one stop either way to cover a ambient temperature range from 5-40C. One easy way round this is to mount the mod on the dash or by the handlebar switches so it can be adjusted on the fly:



If you use Kev's O2 Controller, the ECU still reads a signal from the sensor. The controller just intercepts and modifies the complex signal being sent to the ECU to provide richer closed loop fuelling. The signal still changes according to running conditions.

The Autotune kit doesn't measure air intake or pressure, it relies on a second additional exhaust gas sensor (which you will need to fit into one of the headers). The Autotune doesn't really work on the fly either, you need to work the motor pretty much as you would on the dyno giving it different loads, taking the readings and accepting the trims to the fuel map.

The bike's own AIT and MAP sensors will deal with air temperature and pressure changes as altitude increases. I wouldn't worry. When Damon I'Anson took his XT660 a good way up Everest to achieve the then world altitude record for a bike (18,743 ft or 5713 m), he only needed to mess about with the fuelling (laptop and PC - no Autotune) at the very highest altitudes over 4000m in the last stages of the trip.

You can only alter the A/F ratio with the diagnostic tool by changing the CO setting and this will only have a tiny effect and only at idle up to 2% throttle, which is pretty much unnoticeable on the road.

__________________

Wow what a great explanation. Thank you!

I was always thinking the O2 mod deactivates the O2 sensor and gives a fixed signal. But now when I'm thinking about it. It makes sense to just alter the signal.

Yes your right. Probably the Kev mods are the best to go. I think, I will hide the Fuel mod when I drive at home (due to laws) and will just put it in the front when I'm traveling in other countries.