Load Cell Question.

[k4nnon]

Hey all Im not sure if this is a real issue or not because every car is different and every car runs differently.

When watching my live data, the car seems to always be between load cells and never really directly within load cells unless i am driving and trying to hold it in that particular load cell.

Does this sound normal or is there an adjustment somewhere that will help travel through the load cells instead of between them.

It may all be in my head that i would like to see the car in a particular load cell but with driving and load conditions it may be operating as should and just not within that cell.. figures i would ask some more experienced link g4x users. 

Thanks for any input!!

 

[aerace_fab]

press "x" on the particular screen and change the axis to a load that you're going to spend more time in. 

[Adamw]

The value generated by the table is also linearly interpolated between cells, so it generally doesnt matter where you are working.  If there is some area of operation where linear interpolation between two cells doesnt give the outcome you desire then just add a new row/column at the value you want.  

[k4nnon]

On 5/27/2022 at 6:19 PM, Adamw said:

The value generated by the table is also linearly interpolated between cells, so it generally doesnt matter where you are working.  If there is some area of operation where linear interpolation between two cells doesnt give the outcome you desire then just add a new row/column at the value you want.  

Thanks Adam, this makes sense. I haven’t adjusted any of the row values as of yet but the “in between” cell travel is probably travel through numbers that aren’t in my row columns. Always thanks for the advice! 

[Adamw]

1 hour ago, k4nnon said:

but the “in between” cell travel is probably travel through numbers that aren’t in my row columns.

Huh?  Not sure what you are saying here so I will do a quick example. 

Two basic factors change with load - engine volumetric efficiency and the charge air density.  The charge air density is determined by the MAP sensor and air temp sensor so that is taken care of in the background automatically.  The fuel table's job is effectively only to take care of the changes in volumetric efficiency.

If you look at the fuel table below as an example - this is from a real engine, I have only rounded off the two orange numbers to make the math easier.  This engine idles in the -60Kpa row, you can see as load increases from idle to WOT the fuel table number doesnt actually change much.  In fact the bottom 3 rows barely change at all, I could have removed those last two rows and the fuel control would have still been near perfect.

To explain how interpolation works  - say I were cruising along at 2000RPM, -50Kpa, The ecu would be using a value of 67.5% (ie. half way between the 65% & 70%). 

If I were cruise at -56kpa then the ecu would be using a fuel table value of 66% (ie 1/5 of the way between 65 & 70). 

Even if the bulk of my cruising was done at say -50kpa, you would only need to add another row at  -50 if the VE change between the -40 & -60 row was not linear.  

[k4nnon]

19 hours ago, Adamw said:

Huh?  Not sure what you are saying here so I will do a quick example. 

Two basic factors change with load - engine volumetric efficiency and the charge air density.  The charge air density is determined by the MAP sensor and air temp sensor so that is taken care of in the background automatically.  The fuel table's job is effectively only to take care of the changes in volumetric efficiency.

If you look at the fuel table below as an example - this is from a real engine, I have only rounded off the two orange numbers to make the math easier.  This engine idles in the -60Kpa row, you can see as load increases from idle to WOT the fuel table number doesnt actually change much.  In fact the bottom 3 rows barely change at all, I could have removed those last two rows and the fuel control would have still been near perfect.

To explain how interpolation works  - say I were cruising along at 2000RPM, -50Kpa, The ecu would be using a value of 67.5% (ie. half way between the 65% & 70%). 

If I were cruise at -56kpa then the ecu would be using a fuel table value of 66% (ie 1/5 of the way between 65 & 70). 

Even if the bulk of my cruising was done at say -50kpa, you would only need to add another row at  -50 if the VE change between the -40 & -60 row was not linear.  

That’s exactly what I was meaning to say. I understand what you are saying and that’s what I was meaning. Thanks for the input. I think I have it figured out now!