OBD1 8bit M Bar

Assuming that the stock map sensor's maximum reading is 1764 Mbar, the formula to convert MAP byte value is ((1764 / 255) * [[OBD1]] _8bitMBar / 2). When the rom's map value has been [[uncorked]], simply remove the last division which results in the formula ((1764 / 255) * [[OBD1]] _8bitMbar).

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OBD1 Honda Map Sensor Information

Stock Map:5/255*((Raw/2)+Fuel Cut) Boost Map: volts=(5/255)*(Raw+fuelcut) **Fuel cut stock is 24 and editable at 0x4dcc**

2.85 V=0 "1.0V=20" (20-0)/(2.85-1)=m (y-0)=20/1.85(x-2.85) inHG=20(volts)/1.85-30.81

2.85V=1013mbar "1.0 V=336mbar" (1013-336)/(2.85-1)=m (y-1013)=365.9(x-2.85) mbar=365.9(volts)-29.9

Raw	0	24	48	80	128	176	208	224	240	256
Volt	0.471	0.706	0.941	1.255	1.725	2.196	2.51	2.667	2.824	2.98
mbar	142.3	228.4	314.5	429.3	601.5	773.6	888.4	945.8	1003	1061

 

Raw	0	12	24	40	64	88	104	112	120	128
Volt	0.471	0.706	0.941	1.255	1.725	2.196	2.51	2.667	2.824	2.98
mbar	142.3	228.4	314.5	429.3	601.5	773.6	888.4	945.8	1003	1061

Raw values shown above are for a P72/75. Most if not all OBD1 ECU's follow this rule though so its just a matter of plugging in different raw values. Feel free to edit anything that is deemed incorrect.

-- bigwig - 21 May 2005

Attachment:	Modify:	Size:	Date:	Who:	Comment:
mapsensor.jpg	mod	10674	21 May 2005 - 03:46	bigwig