How exactly is CTC Implemented in Traditional Fuel Mode?

[ThreeTrees]

It's not clear to me how Charge Temp Correction is implemented when tuning in Traditional Fuel mode.  Most Traditional fueling jobs work out great with simple IAT correction so I've never bothered to mess with CTC outside of Modelled Mode, but I ended up pondering this over toast this morning. 

AFAIK there's no ideal gas model running in traditional mode, we're just trimming the master fuel value with lookup tables, so what does the ECU do with the Charge Temp output from the Charge Temp Approximation Table?  Is there some kind of calculation running in the background?  A simple %trim lookup table?

Or would it be necessary to set Charge Temp as the horizontal axis in the IAT correction table to get it into the fuel calculation?

 

Thanks!

[cj]

You are correct, charge temp approximation does not apply in traditional model. If you watch carefully, the table/menu disappears when you swap a tune to traditional mode, and just like you say, you have to go back to using an IAT compensation table.

[Adamw]

11 hours ago, cj said:

You are correct, charge temp approximation does not apply in traditional model.

You can in fact turn charge temp approximation on in traditional mode, it will often work better than using IAT compensation alone.

 

14 hours ago, ThreeTrees said:

so what does the ECU do with the Charge Temp output from the Charge Temp Approximation Table?  Is there some kind of calculation running in the background?  A simple %trim lookup table?

It applies an ideal gas law based correction to the approximated charge temp.  From memory it is zero correction at 20°C, with 0.3% fuel added or removed per 1°C temp change from there (~3% per 10deg).

[ThreeTrees]

On 12/5/2019 at 1:01 AM, Adamw said:

It applies an ideal gas law based correction to the approximated charge temp.  From memory it is zero correction at 20°C, with 0.3% fuel added or removed per 1°C temp change from there (~3% per 10deg).

Oh ok so it's basically a hard coded lookup table.  Just what I was wondering!

 

Thanks!