AlphaN with Boost compensation

[NOTORIOUS VR]

k... i got a question... a good friend of mine likes to tune with TPS as the main load and the MAP as a boost comp.  Now it seems that reading through this and a page on the WIKI that VEMS can do this as well.  But how well would it work? How would you set it up (like where would you put the boost comp? in the higher part of the VE table say? what happens to the timing and lambda tables?

and is it worth it?

Thanks!

Sascha (Schultz)

[rob@vems.co.uk]

Its a good question, the air compensation works using the ideal gas laws to factor pressure into the fuelling equation.
As for ignition, theres currently no ignition correction, so I'd not use it, is he wanting to use a this with ITBs on a Turbo?  If so AlphaN blending would be the thing to go for, if not then Speed Density.

[NOTORIOUS VR]

no maybe I should clarify a little.  My friend who is a seasoned tuner (has tuned many cars for many years and has used A LOT of stand alone units) who prefers AEM management, he tunes with TPS as the main load (regardless of ITB, single TB, etc.) and on boosted cars he uses the MAP sensor as boost comp.

And I'm not too worried about ignition correction as much as if I were to use TPS as the mian load (according to the WIKI I need to scale the load points differently.  But at what point and how do I make the MAP sensor add fueling to the TPS scaled VE table?

I'm not sure if using boost comp would be blending, I'm guessing it would be at a point where we start getting into positive pressure (boost).

I'm asking all this because it seems like an interesting way to tune a car, and would seem that in boosted applications would also mean that once the map is somewhat tuned, it wouldn't matter if the person ran 10, 20 or 30 psi, you would only need minor tweeks to the map.

[rob@vems.co.uk]

I wonder if this is because Speed Density algorithms and interpolation on older ECUs were not always as good as they could be?

I would only use the AlphaN with Boost correction on a car with Independent Throttle Bodies.

Boost corrected ignition is even more vital than fuel tbh.

Rob

[BenFenner]

once the map is somewhat tuned, it wouldn't matter if the person ran 10, 20 or 30 psi, you would only need minor tweeks to the map.

This is the case with Speed Density based tuning as well. Maybe I'm missing something? You should be able to tune the VE table with low boost, then up the boost, tune, up the boost, tune, and repeat until you've got a fully tuned VE table above 100 kPa. Now you should be able to run any amount of boost that you've tuned to, and all should be well. This is how I plan on doing my car once it goes turbo. What am I missing here?

[rob@vems.co.uk]

You're not missing anything, Speed Density handles pressure increases perfectly and with a turbo factors in air temperature which boost compensated fueling does not.

[mattias]

Firmware 1.1.48 now has experimental support for a MAP compensation table on vehicles where you want to use Alpha-N as the primary load.