Thanks for clarifying that a bit more. At any rate though I think our frustration is that we're not finding a table that will adjust mass airflow only based on the IAT. This table we have muddies the water by adding in baro compensation as well. We're hoping for individual adjustment tables. I'm no code writer but I can't imagine that being difficult. (making two separate tables that multiply together that result in something like the table we have now).

 

On another note and since it doesn't seem a more direct table will be found any time soon:

Is there someone willing to write a scaling that would display the horizontal axis in degrees F?

From my calculations the current entries equate to approximately the following:
.78 = 180F
.91 = 106F
1.03 = 33F
1.28 = -40F

I hate to ask someone to do this but I really can't even fathom where to start.

 

What do I get if I write a scaling for you to display degrees F? It shouldn't be too difficult.

Anyway, if I do this for you, you have to absolutely understand, that it will be for one particular baro value (like 1atm). As long as you completely understand this and know that the axis is really air density, then you should be ok. I read through this thread again and noticed that mrfred said the axis is air density and mentioned it is IAT/baro, but density should be baro/IAT. PV=nRT, n/V=P/RT. Maybe the axis is the inverse.

Anyway, either way, I should be able to write some sort of scaling to show you the degrees F, even though that is completely wrong.

 

Eh? I thought .53 = 180F and .78 = 106F. Did I miss something?

 

Actually, I started working on this and I was getting different numbers than mrfred has posted. So, there is an error in my math somewhere. If I get it figured out, I will post it up.

 

The conversion from temperature to "density" units is taken from another table. Its not from PV=nkT.

 

Ah, that would explain it then. I checked my math a number of times and just couldn't come up with the same numbers as you. But, of course I was using PV=nRT.

MY math had the values following the chart that was posted earlier, I think from honki. This table in the ROM seems to be overcorrected by a factor of around 2, roughly, in terms of density at a specific temperature. For example, if I used the axis as density and standardized 32F =1, then the axis would have been (for 1 atm) from .77 to 1.17 (180F to -40F).

 

It seems like the ECU is standardized around 25C from some of the other tables in the ECU.

 

Understood. The x-axis absolutely is NOT temperature, but a sort of representative density. I am okay with knowing in the back of my mind that the temps are only defined for P = 1atm.

I can paypal you $1.04 (to cover paypal fees)

 

I stopped trying once mrfred mentioned that the relation was from a lookup table and not PV=nRT.

 

honki24,

I want it all in pennies in a brown paper bag left on the porch.

Here you go:

You may need to change the endian depending on which version of ECUFlash you're using.

If you use this scaling, maybe rename the X axis in the map to something like 'deg F for air density change at 1atm' or something similar to remind you. Maybe just add the table again with the new changes so you can keep the correct scaling that mrfred gave.


Eric

 

Mrfred, can you post the look-up table?

 

No problem. Just post your home address on the internet!

Thanks man. Wish I understood some of this coding better... lol no time to learn though.



So, to change the x-axis values I can just go ahead and put in these cells whatever I want, right? Like 120F, 100F, 50F, 30F for example?

 

I thought that was mentioned by mrfred to not be a good idea?

The interpolation is linear between the cells, so why not just use the scaling as it is? Is it because you want a non-linear correction?

 

Correct. Do not simply insert temperature values in the axes.