The note in the pc3 box i receved last friday says
2007-2008 xt660 euro modle pc 412-411

Due to the close loop emission system used on this bike it is not possible to make fuel changeswith the power commander between 3500 and 6000 rpm ,below20% throttle

And it is not recommended to disconnect the o2 sensor on these bikes

Thanks Paul so now we know exactly what DynoJet is issuing as a warning, many many thanks for letting us know.

This will help Kev further

Well done dude! :clap: :clap:

Capt,

I have to agree with Freez's earlier post on this subject. Mine is running much much better with the lamdba disconnected as when its connected it appears to be fighting between the YAM engine mgmt system and the PC3.

However, in a PM to Kev i will await the true experts advice on this. I have emailed Dyno-Jet UK directly on this subject as i know one of the main men there, so hopefully we can try to understand the issue and lets see that if its a YAM problemo that they look to remap their s/w

Fingers crossed one and all.

Cheers

WB

I am a bit confused with Dyno jets statement. The problem is between 10 to 20% throttle 2200 to 3800RPM, not 3500 to 6000rpm, you can map this area with no problems.

It's not that I don't trust what CCC is saying, I just like to know all the facts.

Let me just warn you, that there are different types of PCIII's.

You get a road legal version (PCIII EX) and a race version. The road legal versions have limitations and will not allow you to remap certain RPM ranges. They made this so riders cannot mess around with the emission law regulations and make the bikes illegal to ride on the road. Maybe they introduced this with the new XT PCIII's.

If you read the race version instructions, or the normal PCIII we have been using for a few years now, you will see it is not road legal and must only be used for racing where emission laws do not apply.

I was under the impression that the road legal versions will not allow you to map anything below 4000 RPM, but anyway, that�s what I thought, might be wrong and differ from bike to bike.

The race version you can do what you like with and map any RPM and throttle range.

Some things still don't make any sense here.

One side say to disconnect and another say to leave it plugged in.

Disconnecting it and not running the O2 eliminator will most likely bring up an error message on the XT and also send the ECU to run some sort of default fuel map or something like that.

The O2 eliminator is only there to give the ECU a fixed reference point to do your mapping from and to prevent an alarm.

Leaving it in might cause the ECU to override anything the PCIII tells it, so making the PCIII useless for certain RPM ranges. That I can understand, but if this is where to bogging comes from, it will remain there.

Sure the bogging is caused by either ignition of fueling and if it is fuel related, then the PCIII should sort it out, assuming you can disconnect the O2 sensor and preventing the ECU from trying to make constant changes and you use the race version of the PCIII.

I think we are dealing with multiple issues here.

One, could the new PCIII's be the EX versions or running the EX software preventing us from mapping certain RPM ranges and the bog remains, or is there something else involved. Maybe they want you to remain road legal so they are forcing you to use the O2 sensor.

I cannot understand why the O2 sensor removal will cause the bog if the fueling is right. If you can set up the fueling correctly with the PCIII, it is right and any bog must be caused by something else.

The O2 sensor is basically a resistor that remains fixed and provide a fixed reference for the ECU. Why is the fixed reference causing a problem? It makes no sense to me.

In my mind, if there is a bog, and it is caused by the stock ECU providing the incorrect amount of fuel to the motor. To fix it you have to remove the O2 sensor, force the ECU to use a fixed map, since the reference never changes and then remap it with a PCIII race version to get the fuel delivery correct.

If the fuel is right and there is still a bog, then the only other thing that can cuase it is ignition.

A reply from Dyno Jet today.

While testing this bike over the last month or so it has become apparent we cannot disable the O2 sensor with the eliminators we already have, we also found just disconnecting the O2 sensor caused a lot of problems, chiefly the bike will cycle very rich during cruise situations.

We are currently working on a solution, however as it isn't going to be an immediate answer we have decided to release the XT660 power commanders with a note attached explaining that:



"Due to the close loop emission system used on the above bikes it is not possible to make fuel changes with the power commander between 3500 and 6000 RPM, below 20% throttle.
It is not recommended to disconnect the O2 sensor on these bikes."

The surging in caused by the bike running too lean during cruise situations. We have not "contacted Yamaha".

Hope this clears a few things up.

Martin.
Dynojet UK
01995 600500
www.dynojet.co.uk
************************************************** ************************************************** *****************
When I get on the Dyon next I will do some testing with the PCIII. I do not think I will be running my O2 sensor with my PCIII for now, it does not make sence to me.

Ok, one thing sorted out.

So you have to run with the O2 sensor plugged in.

Now the next question.

Kev, you built the O2 sensor eliminators. Did you use pure resistors in it or does it contain other electronics also?

I am not sure what output the XT O2 sensor provides, but if the ECU is needing a voltage, then I can understand why the resistors are not working. If we need a voltage instead of resisitance then it should be a simple matter to sort out.

All we need to do is figure out what voltage that O2 sensor sends out at an A/F ratio of 13:1.

Once we know the voltage, all we do is build a little voltage regulator and we send a constant voltage back to the ECU, tricking it into thinking the O2 sensor is working correctly.

It will be cheap to build and since we have voltage going to the sensor anyway, we can use that to power the voltage regulator.

I found this info on another O2 sensor.

http://wbo2.com/2a0/svout.gif

If the output of the Xt's sensor is simmelar, all we need to do is build a regulator with a constant 2.2V output and the job is done.

It is easy to make the voltage regulator as that was what I was going to do before I saw what Dyno jet was doing with their O2 Eliminators.

The problem lies deeper then we think, I think the problem occurs when the TPS is around the 15% & the ECU switches between closed loop & open loop position.

What I want to try first is move the TPS to different postions & reset the zero postion everytime on the PCIII to see if it move the surging around the rev & throttle postion range.

I see.

Does the ECU go from open to closed loop at around 15% or closed to open.

The question still remains as to why some XT's surge and some don't. If the all run the same ECU's and software then let's remove that from the list of problems.

This leaves me with the following.

Did they have a bad batch of O2 sensors, where some sensors had a different output voltages or that the output tolerance on these sensors are to wide that it causes wrong inputs to the ECU or maybe it is the fuel or some of the other sensors on the bike causing problems.

On the 700Raptors I have had a lot of them with TPS sensors going faulty, so maybe it comes from the TPS itself.

Kev, you mentioned that you had 2 XT's and one would surge and the other not. Where both mapped with the tuninglink and both had the o2 sensors removed???

Anyway, lets see what you find.

Hi guys

Anymore news on this issue?

I fitted the Kev mod at the weekend and the sensor eliminator. (Very well made Mod Kev, Thanks.) :notworthy[1]:


Should I refit the sensor or not? I'm quite happy to fit it back in but will it mess with the Kev Mod?