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Second Sensor for Continuous Baro Correction

Posted: Wed Jul 29, 2009 4:39 pm
by ROCKET455
Not uncommon for me to drive from sea level to 14,000 feet. I want to be set up for real time Baro correction. During my research, I believe this is what I need: MX4250AP sensor, Pin 1 to JS5, Pin 2 to ground (non-banded side of D1 which my configuration dosent use D1 so the hole is ready to use), Pin 3 to +5 location in proto area thru a 1K 1/2 watt resistor (I assume the +5 volts is from the layered PCB - two holes available, either one can be used). Setup is MT 255 under "Fuel Set Up", "General Settings", "Barometric Correction", Two Independent Sensors". No other settings needed. Diagnostics to check sensor operation is to change a gauge to "Barometer" in MT 255. If I missed anything please let me know -As alway, thanks in advance!

Re: Second Sensor for Continuous Baro Correction

Posted: Wed Jul 29, 2009 5:39 pm
by TheMonkey
i think pin 1 goes through resistor, not pin 3.

don't forget to calibrate the table in flash according to specs of the sensor you install, although the one you listed may be in as default - but don't bet on it.

sheesh.... 'normal' to drive sealevel -> 14k feet? that is up there. you have link to pics of your truck? 48 = very cool.

Re: Second Sensor for Continuous Baro Correction

Posted: Thu Jul 30, 2009 6:00 pm
by ROCKET455
Thanks, you were right, pin one thru resistor and pin 3 to 5 volts. I wired it up tonight and all i get is 260 kPa reading so sensors not working. It there 5 volts at 5 v location in proto area or do i need to pull in 5 volts?

Re: Second Sensor for Continuous Baro Correction

Posted: Thu Jul 30, 2009 6:47 pm
by ROCKET455
Went back and rechecked wiring, not getting 5 v to sensor. problem was at ground on non banded side of D1. Moved ground to neg in proto area and works fine now. Does anyone see any problem with using neg in proto area?

Re: Second Sensor for Continuous Baro Correction

Posted: Thu Jul 30, 2009 9:50 pm
by TheMonkey
hmm. you know what... if you look at schematic for 2.2 board, the non-banded end of D1 is a ground, but the schematic for 3.0 board is jump from tach select through optoin.

the instructions for adding a second baro is to ground at non-banded end of D1 which seems to be legacy from the 2.2 board. weird part is that when i built a 3.0 board, i was reading from same manual and i don't remember same hiccup. i must have grounded straight to the proto ground like you eventually did.

anyhow, i think the idea of grounding at non-banded side of D1 was to ground at same point as ground of first baro sensor which you could do at pin 2 of first baro sensor in either case, but the proto ground is fine too.

Re: Second Sensor for Continuous Baro Correction

Posted: Fri Jul 31, 2009 4:24 am
by ROCKET455
Thanks again, cant wait to do some final tuning!