Load calculation logic on CSL software: how does it work?

[Pavlo]

Hey all,

I've been fine tuning my engine that has a bit of an unusual setup so its off all over the board even with an off the shelf tune from a reputable fellow. I use testo to log the parameters but questioning how load is calculated. TPS? MAP?

What is the correct way to log load so that I reference the correct cells when making my changes? When I look at the VE tables, how is the Y axis calculated on the CSL?

Thank you.

[Tomba]

The y-axis/load axis represents engine filling rate. 100% on a stock engine mean 3246cc of volume in air. I believe the ECU calculates this to mass flow rahter than volume flow. Since the engine plant is based in Munich the air pressure and temperature there are used as a reference. From memory its not 1013mbar/20°C but lower ambient pressure, something like 960mbar. Normally density @ 1013mbar/20°C would be 1.2041kg/m3 but it is lower, something like ~1.12.

When the engine runs at a load of 1.0 / 100% it means
3246cc/6cylinder
541cc/cyl
density of 1.19kg/m3= 1.12mg/cc
606 mg/stroke is entering the engine.
Knowing the injector constant and fuel density you can calculate the correct activation time of the injector knowing your target lambda. In old Bosch Motronic ECUs the load was the base activation time of the injector, based on that calculation.

Once you use a MAF you already know the amount of air entering the engine. In some cases the cylinder spools and you get less air in the cylinder than actually is measured. You need compensation tables for this based on camshaft position.
I also believe the alpha/n table in the ECU represents the air filling based on TPS position. Probably a few other corrections.

I believe the CSL S/W uses 2 models, load based on TPS and load based on MAP. If you use Testo logging software and use the serial/ds2 connection, select the VANOS values. Below should be some value like load/engine filling based on MAP.
There could be alpha/n map representing engine filling but also a MAP/n map (speed density). The engine calibration engineer can decide which one to follow at specific engine loads and speeds.

The base fueling table is more like a lambda correction table. Based on an operating condition a final correction can be made. Were 128 8-bit decimal equal a correction of 1 (no correction). Lower values mean less, higher values present a higher correction (more fuel).

How it exactly is being calculated, I don't know for sure. I have to look through my documentation.

Hope this helps either way.

[exodus454]

Most of the load axes are AQREL or RF which is a calculated value, if you log TPS or MAP it won't match up.

[SliM3]

Most of the load axes are AQREL or RF which is a calculated value, if you log TPS or MAP it won't match up.

Yep, AQREL is the total calculated area (square millimeters) of the throttle body openings, relative to throttle plate position.

RF represents a percentage of total kg/h @ 100% VE per working cycle (720*). The value is written in the program section of the tune, and equals 30 kg/h @ 2000 millibars, hence a max RF of 2.0. Change these values and you can have a DME that’s capable of controlling air/fuel up to 4 bar (max of 60 kg/h).

[Pavlo]

Yep, AQREL is the total calculated area (square millimeters) of the throttle body openings, relative to throttle plate position.

RF represents a percentage of total kg/h @ 100% VE per working cycle (720*). The value is written in the program section of the tune, and equals 30 kg/h @ 2000 millibars, hence a max RF of 2.0. Change these values and you can have a DME that’s capable of controlling air/fuel up to 4 bar (max of 60 kg/h).

Got it, I figured that was the correct one to use but had no idea how its calculation worked, thank you!

[terra]

Yep, AQREL is the total calculated area (square millimeters) of the throttle body openings, relative to throttle plate position.

Technically it's the calculated area of the throttle body openings + the "effective" area of the ICV opening.