A change of the VEs of about 8% is about 1 AFR. I advise leaning on the VEs about 3-4% at a time. You will find that changes on the front VEs will have some effect on the Rear AFRs.

Beast

 

I normally don't adjust the tune using VE values - meaning once they are accurately set, I change other values in the calibration. I use the available tools like Log Tuner to set the VE tables as close to possible to what the bike is doing (that is what LT does by doing analysis of the logs) and then adjust the AFR table if I want to make a certain area richer or leaner. By setting the VE tables as an accurate reflection of the bike, the other tables can use this as a basis for calculating fuel delivery when you change other values in the tune.

If you are running in closed loop you can adjust richer or leaner with the Closed Loop Bias table. When running in closed loop, you are still limited to the narrow band of the stock O2 sensors whether you are changing CLB table or VEs.

 

Dennis

That all works great with the big twins but with the Sportys you almost have to run open loop. PVTune appears to be busted on the Sportys as none of us have been able to get it to work. Once we get VEs set close, we then go to open loop at sat 14.3 AFR and chase out the pesky lean holes that always seem to show up. And then we go to slightly richer AFR targets to get the bike to run. It works fairly well.

Beast

 

Thanks. I understand and agree with wanting to have the VE values correctly calibrated for your particular setup then adjusting the AFR table/CLB settings to richen things up, but you can only go so rich (which is not very rich at all actually) in closed-loop using the CLB values before you max out their usable range. I think at this point if you want to run closed-loop and further richen up the AFR you have no other choice but to adjust the VE values upward in the desired areas to get the desired result.

 

Thanks Whittle.

 

Adjusting the VEs upward could also take the stock O2 sensors outside their range. They are just measuring the AFR after all so what ever effects AFR would be read by them. So taking the bike out of closed loop, having the VEs set correctly and adjusting the AFR where you want it would be the only way to get richer than the O2 sensors can read - 14.4 or so

 

I understand. I run open loop on my bike as well, I have the AFR set to 14.1 - runs cooler, better performance and good mpg. I think we are saying the same thing. You are also describing setting the VEs then tuning with AFR in open loop.

 

Thanks Dennis, that is a very good point and one that I did not think about. I wonder if increasing the VE's could actually make the bike run leaner in the closed loop areas?? ie If the bike thinks the VE is higher in a given area (or you make it higher than it should be) would it in turn pull more fuel than it should to try to get the AFR down to 14.6 and actually make the bike run leaner until the sensors had time to adjust? I assume that the ECM uses VE as part of the calculation to determine how much fuel to add even in closed-loop. I assume that if adaptive control is ON, this may even affect open loop values as well.

 

FYI to people reading this thread. I have a data log off a bike that Dennis tuned and it is a very well tuned wideband install. My hat is off to him.

Beast

 

The ECM uses VE as the primary factor in determining fuel delivery as it represents the "predicted" airflow model. If you raise VE values the ECM delivers more fuel if you lower it less fuel is delivered. If you have a closed loop calibration the O2 sensors are used as a control function to maintain the mixture set in the AFR/Lambda table, if you set the VE higher than required the O2 integrator will move the mixture to meet this target as it toggles from rich/lean, it will then eventually store an adaptive fuel value in block learn in the background of the calibration