Engine Load Normalized in Fuel Table

[Mobne]

Please hurry up This is the only thing I’m waiting for before tuning will start.

[Mobne]

Need some advice.

I get “high” numbers in the estimate table on full load.

I’m currently on about 0.3bar boost and I see numbers around 130-140 on 100% tps in the estimate table.

Is this normal? The fuel model should adjust for boost in the background and I should not need to use the boost compensation already because there is no back pressure at this point.

Engine is about a true 106 VE in N/A configuration.


So is the numbers in the estimate table when tuning with the multi throttle method not relative to VE or is something off with my calibrations.

Engine charge cooling gain is set correct and behaves as I would expect.

[NathanB]

Hi Mobne,

If you are re calibrating the 100% throttle column at 30kpa of boost, I would expect the value to be 130-140. That's because the estimate table is not VE - it is the estimated/calculated/expected manifold pressure for that throttle opening/engine speed. These numbers are representative KPA of manifold pressure.

Your VE is set as 100% - You have the VE set as a single value.

So if you think of it in a normal calibration where manifold pressure is the load source your table looks like this (GTR efficiency table)

Efficiency table.jpg (1.09 MiB) Viewed 3756 times

What your table in effect looks like before with 0% in the efficiency compensation boost table is this:

100% VE.jpg (1.32 MiB) Viewed 3756 times

Now if we go back to the start file, and look at the engine efficiency above 100kpa, we have the following:

Eff compensation.jpg (1.21 MiB) Viewed 3756 times

These numbers are above 100%. Not by much, we have numbers just shy of 120% VE. at the high RPM/load areas the engine has lower VE due to exhaust back pressure, but in the mid range where there is cam overlap etc the VE numbers are higher.

Now if we were to combine the changes in VE from 100% vs manifold pressure, our efficiency boost comp table would look something like this:

estimate table with boost pressure comp.jpg (763.17 KiB) Viewed 3756 times

Once you have tuned the estimate table, for your 100% throttle, you leave it alone.

When tuning boost/turn up boost levels, you tune the efficiency boost pressure compensation table. This table even has a "Q" function. As previously described, this table is to account for the change in VE. depending on the engine combination, cam timing etc, the VE increases with boost to a point before backpressure ratios increase and pull this efficiency back down.

In your use case where you have a good, stable manifold pressure signal, there is no benefit in using estimate based tuning. The reason this strategy was implemented was for multi throttle engines that have very poor manifold pressure resolution/inability to accurately measure the manifold pressure. You are unnecessarily complicating things for yourself.

[Mobne]

Thanks for the help!

I went back to the normal tuning method. The map signal is good enough and only a quick street tune still makes it run good.

Big thanks to you NathanB!