Wednesday, December 21, 2011

Second Baro

I've decided to add a second baro sensor for real-time baro correction.  I'm doing it for three reasons:

1) If I use "default baro" I don't compensate for both changes in the weather and altitude.  It'll change behavior (lean/rich) with high and low pressure weather systems.

2) I've found that if I use "initial MAP reading" I will occasionally get bad sample readings that effect the fueling for the entire drive until the car is restarted.  It will also change mixture slightly as I change elevation.

3) I just feel like it.

$18, shippped, from Mouser

Signal out, ground and power.  Vout, pin #1,  has a small notch in it.

Signal out to JP4. I epoxied it in place to prevent vibration damage.
 It works well.  My Baro correction factor will change from around 99.3 to 100.7 depending on the weather and the +/- 500ft elevation changes in my area.    The calibration of the sensor should be identical to the default sensor, it should give a correction of 100.0 at 100Kpa on the engine MAP sensor.  If it doesn't you can use the baro correction table.