the injector flow rate table..

[ZL1Killa]

I was noticing that when I put in some exact numbers into this table from an excel sheet (injector flow rate calculator sheet) and I saved the tune in EFI LIVE and then exited and came back and brought up the injector flow rate table (B4001) that the numbers were a little different from what I had put in.?? a little weird to me.

I noticed that when i used 53.5 psi and i saved and came back that EFI LIVE lowered the numbers compared to what I put in. Then I used 54psi and saved and reopened the file and it gave me higher numbers than what I put in.

just . this is my injector flow rate calc

[Black02SS]

This is correct. Paul explained this to me one time but I don't remember his reason. It isn't a bug as it is what the PCM does I believe. I'll look to see if I still have that email.

[ZL1Killa]

cool, I was just curious. It didn't adjust the numbers a lot but i was just wondering why they did change

[Blacky]

It is due to the precision of the data stored in the PCM.
The PCM stores each single cell's value as a 16 bit number.
That means each value can only have 1 of 65536 distinct integer values.

For example (assuming the precision is 1/64 per bit - it's probably different to that, I can't remember of the top of my head) the value 10.1234 grams/second would be converted to 10.1234*64 = 647.8976. Since the value MUST be stored into a 16 bit integer value (with no decimal places) the value 648 would be stored in the PCM (or *.tun file). When that is read back again it would be converted back to grams/second like this: 648/64 = 10.125

The same rounding occurs with ALL calibrations, it is just more noticable in the injector flow rate calibration because it uses 4 decimal places of precision.

Regards
Paul

[mistermike]

I've noticed that as well when dumping maps into a spreadsheet. Lotsa digits.

[TAQuickness]

I've noticed that as well when dumping maps into a spreadsheet. Lotsa digits.

Try changing your map to display 6 decimal places.