Six_Shooter

iTrader: (2)

Something that is a bit confusing, especially since this seems to have different "values" between different masks.

In some masks, like $42, have an actualy value that matches the number of cylinders, 8 cylinders = 8.

Where as other masks, such as $A1, $8F, use a value of "192", for 6 cylinder.

Would this be a displacement value the case of A1 and 8F? That would limit these bins to be used on a max displacment engine of 255 cu. in.

I haven't been able to find any 8 cylinder bins yet that show a cylinder select value, I've looked at a few $8D bins, which had a value of "0.00" in the "cylinder number" constant. I would assume that this would be one of the mentioned bins/masks that requires the cylinder select to be designated by the MEMCAL.

Then there's code 59 that uses hex values for cylinder select.

Any insight into this?
The reason I ask is that if I'm correct to assume that the $A1, $8F type 6 cylinder bins are by displacement, I need to adjust this in a couple bins I'm playing with.

RBob

iTrader: (1)

It doesn't matter if the cylinder select is in decimal or hex, as they can be converted between:

192 decimal = $C0

The cylinder select in the calibration is so that the ECM can convert the spark timing from degrees to a time based value. Very important to have it correct.

Different code bases use different methods for this calculation, hence the different values used in the cylinder select parameter.

RBob.

Six_Shooter

iTrader: (2)

Ok, but that doesn't really answer my specific questions.Is this value just an arbitrary value, that signifies a devisor to be used for the cylinder number/ignition pulses?
I.E. 192/C0 is just a devisor for 6 cylinders?
If that's the case, why is there a selection for TBI in the code 59 mask?
What would that do when selected?

I did some searching last night and read some threads and there really doesn't seem to be a definitive answer. I've only been looking on TGO, since when ever I've looked for information in a general websearch, I alwasy get pointed back to here, or DIY-EFI, which seems have a lot of missing data in the last couple of years.

Pop45398

What are you using to read these values, Tunerpro or something similar? You must be using something besides a hex editor if you are seeing decimal numbers. There may be errors, such as in addressing, in the config file. To be certain you are looking at the proper values, find out the address for the cylinder select term for each mask you are interested in (as they might not all be in the same location) then open the .bin file with a hex editor and go to the proper location.

I believe the selection is done by bits, not by a value, per se. As for the TBI in $58, that was likely the fault of the person who setup the config file--probably just cutting and pasting from another config file.

Six_Shooter

iTrader: (2)

Yep, Tuner Pro RT.Proper xdfs for the bins I'm looking at.

The 192 value seems to match up with the hex, as in max of 255.I could look at the raw hex, but that wouldn't have helped me at all so far.If it's just a hex value that selects the cylinder count, then it would be easier to show raw hex, instead of the calulated hex value.
Basically I'm just trying to understand if there is some sort of displacment calulation based on the value and if I should be concerned or not.
If this is a simple cylinder number value for this, then are all GM bins using the same hex values for this? I.E. 6 cylinder equals C0 or 192?

Pop45398

It's not a displacement value, just a simple hex value used to calculate RPM. The code needs to know the number of cylinders so it can properly divide the reference pulses. If it's an 8 cylinder (00) there is no division, else the values are used to scale to 8 cylinders for the calculation. This same calculation is used in $32, $58, $6E, and $8D masks. It's probably safe to assume other masks use this the same way as well.

Six_Shooter

iTrader: (2)

Ok, that makes at least some sense.

Thanks