First of all I apologize for beating this one to death again.

I have archived a lot of posts about how much you can adjust the AFR when you still have stock o2 sensors and you're using a tuner such as SEPST, TTS, etc (not piggy back ones such as PCV). In some of the posts it says that you can't really change the AFR that much as the stock o2 wont allow it and will limit the range of what can be done. I would like to continue using the o2 sensors and use a tuner to improve the AFR mainly in the cruise range. thats all im trying to accomplish. Just a little more fuel. How much can i change the AFR before the o2's slap my hands?

I have a 2014 UCL, catless header, SE slip ons. Still trying to figure out what im going to do with breather.

thanks

 

You might be a bit confused...

you can change the AFR (Lambda) to just about anything you want. Below a certain number, the system goes into open loop and the onboard O2 sensors (wide or narrow band) no longer provide accurate data.

If you want to accurately measure the mixture at a lower number, you'll have to use a standalone probe system.

 

PT thanks for the response and i'll admit im confused. when you say stand alone probe system, what does that mean?
thanks

 

AFR probe inserted into the exhaust system when it is on a Dyno.

 

at what AFR does it go to open loop?
thanks again

 

I've been asking myself the same question. What I've dug up from reading thread after thread and article after article I think I may have found the answer.
It's to my understanding that the NB02 sensors only operate accurately within a 14.2-15.0 range (.964-1.015 Lambda) this is +/- .4 from the stoch mix of 14.64 (Lambda 1 being 14.7). I believe anything outside of this range would put the bike in open loop.

To make an improvement in cruise you can change the A/F ratios in those cells, I run a mixture of 14.3 in cruise as oppose to the 14.7 that was stock.

Here's a somewhat outdated chart that I found.
http://tuneyourharley.com/biketech/c...band-o2-sensor

To see what is really coming out of your engine you'll need to have it sniffed just like the above posts say.

 

The AFR number is generally 14.6 (.971 lambda IIRC).

This number is simply a switching point for the system to go into open or closed loop.

As mentioned above, a probe is placed into the tail pipe and the measurements are taken. Depending on the equipment used, data can be sampled and analyzed over a much broader area when compared to onboard O2 sensors (narrow or wide band).

When you say you want to improve the AFR in certain areas, what are you trying to accomplish?

 

On your bike... you should be able to have 'closed loop' from around 14.3 to almost 15.0 AFR.

Here is how this works and you don't really need a 'probe' to tune with, but is sure works out better.

With a TTS, you will use the stock sensors to gather all of the information to make what is called a VE table. Probes would be needed if you wish your Wide Open Throttle (WOT) VEs to be 100% correct. Once you have the VEs set, THEN you make whatever AFR table you wish. ANy table will NOT be 100% open or closed loop. Cruise will be closed loop normally. TTS, SEPST, and PV will not get that WOT area exact. There is an add on to the PV that helps, and uses wide band sensors. If one pays attention and uses the various 'tools' tuners come with, one can get close. I, myself, as a Dyno tuner, always use the sensors that Pine tree is discussing.

Since you can have a proper set of VEs... you simply set the fuel where you wish, or use the base map settings, again TTS has good base maps. There are the 'fueling' portions of the internal map... what tells the ECM what AFR to use in any given circumstance. Using my dyno, I have found that, in cruise, etc areas that are closed loop... 14.4ish AFRs work very well. Whatever you may know from cars and carburated bikes goes right out the window with EFI. EFI, on our bikes, pinpoint each area of engine load+RPM+ Throttle position.

It is a couple step process to "tune" a bike and it is not simply just adjusting fuel.

You can do TTS on a DIY basis, or you can have a pro tuning shop do this for you. OP, you will get a lot of discussion on exactly WHAT tuner to buy... so I will throw in my personal favorite is the TTS.

And... with your bike... I would keep areas of closed loop in operation. Some Dyno guys equipment doesn't allow for them to figure out how to do this correctly and will wish to tell you open loop is the way to go. NOT SO!

 

what im trying to accomplish:
I have read numerous times that the bike comes stock "a little lean" to begin with. So if I change to catless header, bigger air cleaner and slip ons that are a little better sound, I figure that I will lean it out even more. So if i can improve the AFR for these changes as well as the lean it had when it came new, im assuming that it will cool down the engine somewhat, which i think is always a good thing. I'm not necessarily looking for performance improvement as the bike runs good as it is.

And I will tell you that I'm not looking for some dyno chart that I can post on this forum and beat my chest and act like im superman. Ive had dyno runs where it was all about the chart and not about what was best for my riding habits. To be honest with you, and this will show my true ignorance of dyno's, I dont care what it does at 4500 RPM and higher cuz i never go there. All i want is good performance and a cooler engine (if possible) up to 3500, I rarely go higher than that.

 

Add a HD stage 1 a/c pretty much any decent exhaust and a Sepst, cables, cd, load the stage 1 map for your model and ride on as happy as the day you bought it.
Not knocking the TTS and have used it on a few bikes.