map sensor reading

[Seight-v8]

hello all,

Should the map sensor read the same as atmospheric pressure when not connected or when engine is running.

Can only get mine to read a max of 90kpa, and it still about 10kpa out from actual pressure readings.

cheers

scott

[Sprocket]

You need to calibrate the MAP sensor, and ensure it is the correct range

[emil@vems.se]

Here is map sensor calibration info from Vemstune help:

Sensor	Calibration scale
115kPa	104kPa
250kPa	250kPa
300kPa	304kPa
400kPa	414kPa

Set this, then if needed, adjust offset to calibrate to known barometric pressure

//Emil

[GintsK]

Here is map sensor calibration info from Vemstune help:

Sensor	Calibration scale
115kPa	104kPa
250kPa	250kPa
300kPa	304kPa
400kPa	414kPa

Set this, then if needed, adjust offset to calibrate to known barometric pressure

//Emil

Emil, IMHO here is errors.
My experiments and MPXH6300A datasheet gives another result: range should be 315.1 and offset 1.1.

I will check rest of datasheets and report!

Gints

[GintsK]

Here is the results:

http://www.freescale.com/files/sensors/doc/data_sheet/MPX4115A.pdf

115KPa sensor: offset 10.6 range 111.1

http://www.freescale.com/files/sensors/doc/data_sheet/MPX4250A.pdf

250KPa sensor: offset 10.0 range 250.0

http://www.freescale.com/files/sensors/doc/data_sheet/MPXH6300A.pdf

300KPa sensor: offset 1.1 range 314.5

http://www.freescale.com/files/sensors/doc/data_sheet/MPXH6400A.pdf

400KPa sensor: offset 3.5 range 413.0

All four matches with results on real board by applying 0V and VCC to sensor input.

http://cache.freescale.com/files/sensors/doc/data_sheet/MPX5700.pdf

700KPa sensor: offset -31.1 (negative!) range 777.7

Calculations is done this way:

1) calculated theoretical presures at 0V supply Result is offset.

2)calculated theoretical pressure at V_supply=V_out

3)subtracted both resulting pressures = range

Gints

[z0tya]

Why need to set 315.1 range when the data sheet says 20 to 304 kPa at 3 bar sensor?

Thx

[gox]

i just installed unit with 250kPa and offset is 10kPa,so its true.

[GintsK]

Why need to set 315.1 range when the data sheet says 20 to 304 kPa at 3 bar sensor?

Thx

Range here is mathematical not physical value. Physically then range is just 304-20=284Kpa.
 But ECU calculates MAP value mathematically. datasheet give also line equation for this calculation. My values comes from there and verified on bench test.

Gints