Who's Your MapDaddy?

MapDaddy 4 Bar MAP Sensor with Barometric Correction

Fully compatible with MSnS-E and MS-II, PCB2.2, PCB3.0, and PCB3.57

Ready to rock your ride handling up to 44psi of BOOST!

It's finally here and I've got plenty of them ready to ship-- The 'MapDaddy' 4-bar Manifold Absolute Pressure (MAP) Sensor upgrade for the MegaSquirt, with one primary 4-bar MAP sensor for standard MAP Sensor duties, and a second for realtime barometric correction so that your fueling calculations will stay accurate in the event of an elevation change (mountain runs anyone?). The design was well thought through and is completely compatible with the MegaSquirt-I/MSnS-E firmware or the MegaSquirt-II, as well as with the MegaSquirt PCB2.2, PCB3.0, and PCB3.57 units. Any hardware platform is good to go...

Installation is simple, it just solder right in where the standard MPXH4250 would normally go. One sensor's nipple lines right up where the 4250's output would have been so it will line right up with the hole in your case. A small washer is included for PCBv3 cases that have a larger MAP hole, to be placed on the bulkhead fitting inside the endplate as shown. Then solder the wire from the hole labled 'Baro Out' in the corner of the PCB over to JS5 on PCB3 or 3.57 units, X7 on PCB2.2 units.

NOTE -- you will need about 1/2" of clearance between the PCB and the case. All of DIYAutoTune.com's ECU cases shipped since early 2006 have the proper case, some older kits/ECUs may have a different case without the proper amount of clearance. (Look at the endplates, if the endplate with the DB37 is cutout for the shape of the connector it should fit fine, the older cases just had a rectangle cutout for the DB37 connector and will not fit.)

If you're running a MegaSquirt-II that's all you need to do for the hardware install! You won't need to do anything with the .22uf capacitor included with the kit.

If you're running the MS-I with MSnS-E you'll need that .22uf cap. Just solder it into the C1 holes in between the two MAP sensors. That's it! If you ever upgrade to MS-II you can remove it then... (I tested the capacitor with MS-II with no ill effect I could see, though it's not needed so I don't recommend it with MS-II)

Software Configuration Changes for MS-II (tested with firmware 2.35)

• Before opening MegaTune, open the Megatune Configurator

  • Expend SETTINGS.INI, then SETTINGS, then MAP_SENSOR and set it to
    ”MPXH6400A – MPXH6400 – 400 kPa”

  • Save and exit the Configurator

• Open Tools> Sensor Calibration and set to these values:

Burn to ECU and click close.

• Open Settings>General and set ‘Barometric Correction’ to ‘Two Independent Sensors’ and set to these values:

Burn to ECU and click close. Power the ECU off and then back on.

That’s it! Realtime baro correction is enabled on your MS-II!

Software Configuration for MSnS-E (pre-029)

• Before opening MegaTune, open the Megatune Configurator

  • Expend SETTINGS.INI, then SETTINGS, then MAP_SENSOR and set it to
    ”MPXH6400A – MPXH6400 – 400 kPa”

  • Save and exit the Configurator

• Open MegaTune.

• Under ‘Contants’ turn Barometric Correction ‘ON’. BURN TO ECU and click Close.

• Under ‘Code Config > MAP Sensor Settings’ set:

  • Type of Sensor = 400Kpa
  • Baro Correction Factor % = 78
  • Kpa correction Factor % = 50

  • BURN TO ECU and click Close.

• Under ‘Code Config > Barometric Correction’:

  • The defaults for ‘Max and Min KPA for Baro correction’are normally fine.
  • Set ‘Constant Baro Correction’ to ‘Extra MAP fitted to X7’

  • BURN TO ECU and click Close.

• Power your MegaSquirt OFF and back on—this is required before several of those settings will take effect.

Software Configuration for MSnS-E (029 and newer)

• Before opening MegaTune, open the Megatune Configurator

  • Expand SETTINGS.INI, then SETTINGS, then MAP_SENSOR and set it to
    ”MPXH6400A – MPXH6400 – 400 kPa”

  • Save and exit the Configurator

• Open MegaTune.

• Under ‘Basic Settings > Engine Contants 1’ turn Barometric Correction ‘ON’. Also set the MAP sensor type to 400kpa. BURN TO ECU and click Close.

• Under ‘More Settings > Barometric Correction’:

  • The defaults for ‘Max and Min KPA for Baro correction’ are normally fine.
  • Set ‘Constant Baro Correction’ to ‘Extra MAP fitted to X7’

  • BURN TO ECU and click Close.

• Power your MegaSquirt OFF and back on—this is required before several of those settings will take effect.

That should be it! Note with MSnS-E 024s9 and earlier (and possibly some later versions) there is no ‘realtime’ baro correction, the barometric correction exists in the case of processor resets, so that the ECU will get a clean reading of the true atmospheric pressure if there is a MS processor reset. Without this feature the MegaSquirt uses the single onboard MAP sensor to get it’s baro reading in the event of the reset while the engine is running, the value it gets will be WAY off since the engine will likely have a vacuum, or possibly even boost on this sensor at the time. This can case the ECU to think it’s ‘correcting’ your fuel mixture by leaning it out or richening it up when it shouldn’t be. Adding this second sensor for barometric correction will prevent this from being an issue, as it will take a fresh reading from the second sensor, which isn’t under vacuum/boost but is reading atmospheric pressure, in the event of a processor reset and this issue will never be a problem. Resets should not normally occur anyways and if you have a problem with them you should investigate, they can usually be traced to a power surge on the incoming power supply, or to an interference or a power surge on the ignition input wire.

However-- with later versions of the MSnS-E code, 026h and above I've confirmed, you'll get REALTIME Barometric correction, so all the time the fueling is being adjusted based on altitude and the resulting barometric pressure. This is the ideal situation, it covers the reset issue as well as all altitude changes...