Boost /Load Rows Values For Single Row Stability
 

The PFC tends to start using the next higher boost (load) row when boost is about .5 psi above it. If my load row 17 is set at 12 psi and row 18 is set at 14 psi,
when running 14 psi boost, both rows will be used starting about 13.5 psi and still do it while at 14 psi boost.
This means you have to change both rows for tuning which then also messes up row 17 if you also run 12 psi boost.

To prevent this overlap, set your constant boost rows at load value about .25 to .5 psi lower. For rows 12 and 14 psi, use 11.5 to 11.75 and
13.5 to 13.75. Test log for best results.
*************************
When I do this all of my log values will be 100% in only one timing and fuel row. This will depend on your turbo size, and how well your boost controller works.
Mine has been this precise since 1999 with stock seq twins and now GT35R.
*************************

Now the question: what is this deviation value for the Adaptronic ECUs? Or does it not require it?

Hi cewrx7r1,

Adaptronic ECUs will always interpolate the value between two load points (as well with two RPM points). But for simplicity, e.g. if you have a fuel value of 5.000ms for 12psi and 6.000ms for 14psi, then:

at 12.5psi you'll have 5.250ms
at 13.0psi you'll have 5.500ms
at 13.5psi you'll have 5.750ms

so the value will always depend on the two adjacent load points, but there is no overlap happening.

If it helps, I've also attached a test log that I did on the bench ECU, so you can see the fuel value change as I crank the load input up.

Let me know if this doesn't answer the question.

Thanks.

That is overlapping of cells, and the PFC will show both cells used for timing and fuel since both are being used by interpolation. That is expected when boost is changing up or down.


Now for a PFC:
I am talking about while at a constant fixed boost. The boost load row value in the map setup has to be lower than you actually are running such to keep the used cells only those in the boost row.

Too bad I do not have a log to show this, but I went past this tuning point correction years ago.

For a three bar map sensor running at 14 psi to insure only one row of timing/fuel is used with no interpolation to others rows, the PFC needs the load row set to 13.8 instead of 14.

If you hold the load and rpm values directly on a cell, assuming no compensations are acting, that is exactly the injection or ignition value you will get. If your values are the same across an rpm sweep at a fixed load and you hold that load on a rev you will get exactly those output values, again assuming compensations not acting. I would be very surprised if you genuinely don't get at least minor variance in injector open time or ignition angle with your tuning/logging due to changes in intake and coolant temp however?

Hi guys,

This test is to demonstrate what Slides is saying. I removed all the fuel trims and injector dead times so it's only the fuel map dictating the numbers. I did in KPA to give me more resolution in my particular test.


Cheers.