Hallo,

can anyone tell me how i can determine the map voltage at which the ECU accesses a specific table column?

i know that column 15 is about 3v because thats NA maximum voltage but the rest?! only guessing, not exact.

can anyone help?

ECU is a European PW0.

 

http://www.pgmfi.org/twiki/bin/view/Library/MapSensor

 

Hallo,

thanks for the Info but that was not what i'am looking for.
i want to know what table column are accessed at a specific give voltage not the pressure that the sensor has at a specific voltage.

i ask that because all the MAP scales that going around in pgmfi forum and elsewhere are not 100% exact in my oppinion so i can't get the colum by pressure for sure.

because noone has determined the pressure scales for the PW0 ECU with 100% error free... i think that are all simply guesswork no exact values.

Greets
Malte.

 

...but...

Knowing the voltage that is the pressure value tells you the column headers.

The 0-3v linear voltage is scaled to a 0x00-0xFF value used by the processor.

Each column contains a lower and upper boundry. IE, column 1 is 0x00-0x0F, column 2 is 0x10-0x1F.. so on and so forth for 15 columns.

From the information that was posted, you should be able to calculate the headers....

 

if this is true (from where exactly is this information?) then you are right.

are you sure that the scale is exactly 3,00 Volts = 0xFF?

and 0xFF (3,00v) must corrospond to exact 1046mbar abs. pressure?! right?

i found a pressure to voltage table that says that the stock map sensor has:

1100mbar=3,15v
1000mbar=2,87v

so i calculated: 3 Volt = 0,0028*Pressure + 2,87 Volts
((3 - 2,87) / 0,002+1000 = 1046mbar

do you think thats correct?

if yes then i have a problem solved!

Greets
Malte.

 

I learned that information directly from the PM6 based table lookup routine in the ROM. It's the same as all of the OBD0 ECUs which are restricted to 8-bit math.

You can disassemble the ROM and check for yourself..

As for your calculations, I'll ASSume they're correct. I didn't do them myself.

 

Ok thanks... i will give it a try