I got curious. Performance mod effect on AFR (Air Fuel Ratio)

[5PYD3R]

Just installed JT's air intake a few weeks back and have a few good runs on the Spyder now with it. I run the PC5 with Auto Tune and decided to reset all trim values back to zero to see the changes that the air intake really makes to the bike. So I have a screen shot of the before and after fuel map with going from stock airbox to JT's intake. With the closed loop section there is not a huge difference that you can see at a glance but the parts that are different are fairly significant. Goes to show you that any performance change can give you better results if you were to use the PC5 and auto tune. Obviously every bike is going to be different hence why some will say that certain performance changes don't require a fuel controller while others will. In my mind, by upgrading your exhaust, air filter or the whole intake is going to make changes to the way your Spyder runs (its air to fuel ratio-AFR). It may or may not be enough to notice but the auto tune takes all the guess work out of it and makes your Spyder run the best it can with the upgrades that you have. Just food for thought. I see all to many times where someone will ask about doing a performance mod and asking if a fuel controller is needed. It really comes down to if you want your Spyder to run properly and how much it is worth to you to have the peace of mind knowing its right.

BEFORE JT'S INTAKE:
87645

AFTER JT'S INTAKE:
87646

[jcthorne]

You do realize that over time and drive cycles the OEM controls adjust out changes in air flow and self correct just like the auto tune? Yes, it is more limited in range but it works fine. If you go beyond the OEM range of adjustment (approx 8%), Nanny will let you know as she will set a lean code when the long term trim numbers hit their limits.

The sensor readings are not only used in closed loop. They effect short term trim setting almost immediately (closed loop) but they also offset long term trim settings over time.

Don't assume that just because the air flow has increased that the A/F ratio for open loop is leaner permanently. Its not a fixed tune. Just because you change the air flow by adding a performance increasing modification, its not necessarily time for an aftermarket fuel controller.

What would be interesting to see would be the O2 sensor readings of a bike with JTs Intake and cat bypass on stock controller after a couple hundred miles and the same readings on a similar equipped bike with auto tune controller after a few hundred. Assuming the stock controller does not throw an error with this combo.

[5PYD3R]

Yes I am aware of that. I have had the auto tune on for a while now. Was just posting the difference that the intake made. Not saying that it was a huge difference but worth fine tuning. Every so often I will check the trim values and make sure nothing has changed either. Just posted for fun really.

[SNOOPY]

You do realize that over time and drive cycles the OEM controls adjust out changes in air flow and self correct just like the auto tune? Yes, it is more limited in range but it works fine. If you go beyond the OEM range of adjustment (approx 8%), Nanny will let you know as she will set a lean code when the long term trim numbers hit their limits.

The sensor readings are not only used in closed loop. They effect short term trim setting almost immediately (closed loop) but they also offset long term trim settings over time.

Don't assume that just because the air flow has increased that the A/F ratio for open loop is leaner permanently. Its not a fixed tune. Just because you change the air flow by adding a performance increasing modification, its not necessarily time for an aftermarket fuel controller.

What would be interesting to see would be the O2 sensor readings of a bike with JTs Intake and cat bypass on stock controller after a couple hundred miles and the same readings on a similar equipped bike with auto tune controller after a few hundred. Assuming the stock controller does not throw an error with this combo.


I have the JT and added the Akropovic exhaust and posted my A/F ratio numbers.

Seems to be running fine so far from what I can tell from the numbers. Only 100 miles or so on it though.

I've heard that having my sensor "after" the cat may interfere w/ the numbers slightly, but don't know.

With where my A/F is sitting right now, I may get the cat bypass and see if I can get away w/ that too.

I've been told by one person it will work fine, and told by 20 others it will never work. Maybe we'll see. :)

[5PYD3R]

I have the JT and added the Akropovic exhaust and posted my A/F ratio numbers.

Seems to be running fine so far from what I can tell from the numbers. Only 100 miles or so on it though.

I've heard that having my sensor "after" the cat may interfere w/ the numbers slightly, but don't know.

With where my A/F is sitting right now, I may get the cat bypass and see if I can get away w/ that too.

I've been told by one person it will work fine, and told by 20 others it will never work. Maybe we'll see. :)

This was kinda the point of me doing this. Fact is that it will work depending on your definition of "work." You may get some popping/backfiring or you may not. Every bike is different. What one person does to their bike may not show any issues although it technically could use tuning to get the best performance out of it but another person could do the same thing and have no choice but to do a fuel controller. I was one of those people. I did an exhaust and was fine. Did the K&N filter in the stock airbox and that was just enough to start some issues for me. I could put the stock filter back in and it was fine. So I thought if it was that close to being off then I should probably do the fuel controller. Instantly with the PCV the bike ran fine. The auto tune just helped get the AFR to the perfect mixture across the board. Then I decided to do the JT air intake and that's where I got curious about the differences that mods create and decided to start this thread.