Gen Board/Manual/Config/Manifold Absolute Pressure

GenBoard/Manual/Config/ManifoldAbsolutePressure (2006-03-16 04:43:08)

[[Manual: Detailed.Sensor.Manifold.Config]]

MAP sensor with higher than 510kPa max range

If you want the LCD to show correct reading, but MAP stays below 512kPa (very likely, even the F1 BMW turbo only had higher boost during qualifying, not the race):

in fuelcalc.c kpafill()

change the engine.kpa250 = k;

to engine.kpa250 = k < 1024 ? k+k : 2047 ;

and recompile.

That will double your MAP reading (as if config.kpafac was in 4kPa units not 2kPa), but still rail at 510kPa.

Original behavior - (select with kpafac=00 and kpaofs=00) not really useful

Warning! This is history! The above is the way to go, much better precision, bigger range and easy calibration. This old method will be dropeed!

Basically all that had to be done is to define what sensor was being used. To maintain compatibility with MegaTune, the values were somewhat obscure.

Bad names inherited from motorola ms. Look for config11..config13 explanation in old sources, snapshot here: http://caffrey.dk/megasquirt/files/veconst.h

Configuration Parameter: config11

Bit Value: upper half: number of cyls-1, bit0 0:mpx4115ap, 1:mpx4250ap

Example: config11=39

read it in global.h and URL above. Leave this 00, especially the speed_density bits. It requires experience to get sane results if this is nonzero.

Configuration Parameter: config13=00

Q: What factory-installed sensor is supported?

A: Using a stock sensor is not recommended. We can't support each and every sensor. But the GM 1Bar sensor can be used in the MPX4115 setting.

Special pressure sensors for the brave

If you are otherwise good at measurement theory, ask for details how to use a low-signal (40..150mV signal, v3.x only !) sensor:

either compensated (like MPX2200AP : very linear upto 200kPa and usable for upto 400kPa)
or uncompensated (like MPX700A : very linear upto 700kPa and usable upto 2800kPa :-).

Only if you really need higher than 1.5 bar boost, because it requires some calibration (3 calibration values: gain, gain(temp), offset(boardTemp)).

See [calibration experiment] against the MPX4250AP sensor. It seems that only gain is essential to measure, the typical value from datasheet can be used for gain(temp).

Note that at 4V supply (leaving 1V for series resistor used for sensor-element temperature measurement) an MPX700A's (my calibration value) 120mV/700kPA is almost as high as the MPX2200A's 40mV/200kPa. Unfortunately the MPX200A is out of fashion.

See also