Does the VE value displayed in a log come from the VE table (or tables, if multifuel) or is it a calculated value derived from fuel flow, observed lambda, etc.? If it is a calculated VE, can it be used to tune the VE table?
Thanks in advance.
VE is a part of the speed density algorithm.
It is the value you need to determine during the tuning process.
In the log it is current VE from the table.
Thanks for the quick response.
So the value currently displayed in the log is the interpolated value from the VE table(s). Is the effective VE (as calculated from fuel dose, Lambda, etc.) computed? If so, could it be added to the list of items that can be graphed? It seems that would be useful in evaluating and tuning the VE table. I would assume the autotune tool is doing something similar.
Volumetric efficiency (VE) in internal combustion engines is a measure of how effectively the engine fills its cylinders with air during the intake stroke. It’s the ratio of the actual volume of air drawn into the cylinder to the theoretical volume the cylinder could hold. A higher VE indicates better engine breathing and more power potential.
It is a constant value that characterizes the engine.
You mistake the VE with the injectors PW what is calculated based on VE, air temperature, MAP, lambda target, etc.
I’m familiar with the basics of calculating the injector PW and I appreciate that is a primary task of the ECU. I’m asking instead about an inferred VE based on the fuel dose and observed Lambda. Since you have a known quantity of fuel and an observed AFR, isn’t it possible to calculate the quantity of air and similarly the effective VE? Isn’t that what the autotune tool does? My request is to make that inferred VE a logged variable that could be compared to the VE from the fuel table as a way to evaluate the tune (probably in Data Master).
As always, thanks for your comments.
Now I understand what you mean, something like suggested VE value.
There is a channel Lambda error mult. that shows how you should modify the VE to get desired lambda target.
However I’ve checked the code and it was disabled in v3 (I will fix it for 3.050).
The problem with suggested VE is that in most situation you are not in the center of the cell so this value will be very hard to applied by hand.
The correction percent is muuch easier to use, as you can multiple several cells by this value.
I found a logging entry for “Lambda error mult.”. The values in this example range from 0.44 to -0.32, but the channel config. only allows a minimum of 0.5 and a maximum of 1.5
It appears the current calculation is producing something other than a VE multiplier. Maybe a lamba error expressed as a fraction?
There is a new version 3.050. This channel was modified and now it show the required correction in %. 0 means no correction 50% means the VE should be increased by 50% and so on.
This channel is simply ( 100 * Lambda / Lambda Target) - 100