MicroSquirt.com read only forum (Jan.15,2018)

DGFTurbo wrote:One question i have is it required to use the same MAP sensor for both MAP and barometric correction? Specifically on MS1

The "Extra" firmware can use a 2nd map sensor for real-time baro correction:

http://megasquirt.sourceforge.net/extra ... ection.htm

One question i have is it required to use the same MAP sensor for both MAP and barometric correction? Specifically on MS1

DGFTurbo,

Yes. MegaSquirt-I or MegaSquirt-II both have the option to use the MAP sensor value at power up (before the egnine is running) as a baro reading. The same baro reading is assumed until you cycle the power to MegaSquirt. For most people this is sufficient.

If you are climbing a mountain in one trip and can't/don't want to cycle the power (you are racing up Pike's Pike, for example) then continuous baro with a second MAP sensor is helpful.

Lance.

Thanks,
Missed that the first time i read it.


Ive searched and not found much conclusive information regarding baro correction and a turbocharged car. Will is make a noticeable difference? i realize at WOT the difference should be minimal, im more concerned with drivability while cruising.

Thanks

Darrell

If you live in CO you will need either a second map sensor for baro correction or run WB in closed loop. There is a big difference in driveability at 0 feet and at 3000 - 5000 feet if no correction is made. The WB will pull you in, but you will need to keep it on pretty much all the time, but then I'm not sure it will be responsive enough when you hit the turbo. If it were me in your situation I would rather correct it properly with a second map sensor. I think the O2 would be a crutch in your case.

Thanks again for all the information ya'll. I've ordered the MS II v3.0 kit with simboard as well as the LC-1 / XD-16 Wideband O2 kit.

I plan to do as much as I can with the carbureted setup before moving to TPI. I want to get ignition control running for spark advance ( I have a Mallory Unilite Dizzy and HyFire 4c module ) and ditch the mechanical advance in the dizzy. That should be a good step toward moving to EFI. Also, since I'm running Holley Adjust-A-Jets ( change jetting via an external screw ) I can manually control fuel flow from inside the cab with a little modification. So with live data from the Laptop based on RPM, AFR, and maybe some other things, I can start to learn how things work.

Hmmm - I wonder if I could have the MS control the Adjust-A-Jets to be a crude form of TBI. lol

I'm a bit confused on the schematic to connect the second MAP sensor. Do I just supply 5v to the ref, ground the MAP sensor, then hook up a 1K / 0.25w resistor to the signal line which goes to JP5 / X7 on the v3.0 PCB?

Thanks!

http://megasquirt.sourceforge.net/extra ... ection.htm

What's the cheapest way to get hold of a second sensor? I looked on Mouser for the MPX4250, but can't find it.

I sell them at $18 plus postage. They are also available from DigiKey; check for pricing on MPX4250AP.

--Glen