Originally Posted by
MegatronUK Taken from the FIAT documentation, here are the byte codes that are listed that seem to match the L8/P8 functionality:
RPM (most significant byte), 0x01, 30000000 / DATUM = RPM
RPM (lest significant byte), 0x02, 30000000 / DATUM = RPM
Injection duration (msb), 0x03, 4 * DATUM / 10^3 = milliseconds
Injection duration (msb), 0x04, 4 * DATUM / 10^3 = milliseconds
Ignition advance, 0x05, DATUM 1L/4 = degrees (don't understand this one!)
Intake pressure, 0x06, DATUM * 6.4161 + 45.63 = mmHg
Air temp, 0x07, (see lookup tables)
Water temp, 0x08, (see lookup tables)
TPS, 0x09, if < 30 (DATUM * 0.1848) - 1.41 = Degrees, if >= 30 (DATUM * 0.7058) - 90 = degrees
Voltage, 0x0A, DATUM * 0.0628 = volts
Fuel trimmer, 0x0B, DATUM - 128
Injection timing angle, 0x0C, 720 - (DATUM * 90) / 4 = Degrees
Most sensors need two reads (lower 8 bits and upper 8 bits) to get the data, you then consult a conversion table to transform the value into an actual human readable number. There's also a standard value that is used as a reference to aid in the transforms. There's a value for FIAT/Alfa, my guess is there is something similar for the Cosworth implementation.
Fortunately, with the RPLabs software, the individual sensors can be toggled on or off. What I plan to do this weekend is run the software for each sensor in turn, but grab all of the traffic each time I do so. I should be able to work out if the byte codes are the same for the Cosworth sensor readings as per the Fiat/Alfa docs.
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