Upgrading/changing an assembled DIYPNP's map sensor (boosting past 22psi)
 

I own a:

• Rev built DIYPNP for my 1999 miata turbo.
• A MPX 4250 is already installed on the board

Details:

• MPX 4250 maxes out at about 22psi
• So i need to either:
  • Option A: Replace the 4250 (e.g. MapDaddy)
  • Option B: Add an secondary/external map sensor (e.g. GM 3 Bar)

Questions:

• It seems Option A will require me to un-solder the 4250? I do not trust myself to do this. Can anyone recommend a reliable company/person who I can send the DIYPNP and MapDaddy that can replace the 4250?

• Is Option B even possible with a DIYPNP? Based on this table DIYPNP may not have the ability to run a secondary/external map sensor. Additionally, in Tuner Studio, "Basic/Load Setting > General Settings > MAP Sensor Settings > MAP Sensor Input Port" only gives me the option of selecting "MAP or Off". Not "External" like other have mentioned on the interwebz.

Any additional info on how to get my already assembled DIYPNP to run >22 psi would be appreciated.

Thanks!

I located two pages regarding how to setup a GM 3 bar map sensor on a MS:

• This one is specific to Microsquirt (which i believe DIYPNP is based off of): MicroSquirt® Introduction , but doesn't reference what to do with the existing Map Sensor (4250)
• This one is specific to MegaSquirt 1 and 2, but does make some mention of the existing map sensor.

I'll update if i find other info/conclusion.

I asked the question on msextra forum. Here's the conclusion:

by dontz125 » Sun Jul 09, 2017 7:18 pm

Unfortunately, the MS2 firmware code can only use the board-mounted sensor for MAP. I agree that lifting all 6 pins can be disconcerting if you aren't used to it.
What you CAN do, is lift or clip only the #1 pin, then connect the signal wire from either the MAPDADDY or GM external sensor to that vacated pin hole. Don' forget to provide power to the new remote-mounted sensor, and don't forget to recalibrate your TS tune to the new sensor.

If you want, you can then connect the lifted #1 pin to one of the spare ADC inputs to use as a constant baro sensor.

Hope that helps anyone else with the same question. Thanks!

it doesnt help, cause it's unfactual.

he first sentence conflicts with the rest. the MS2 firmware doesn't care what MAP sensor you use, you can program it to whatever you want.


soldering in a new map sensor would be incredibly easy, even for a complete novice. this is like child's play to anyone else that has built their own DIYPNP. you have a complete drop in option with the MPX5700. Otherwise the only option is MAPDADDY (which imho is $$$$$$$) or the external.

with the external, you'd still have to mod the DIYPNP slighty, but it would be basically what is outlined above--I would bring it in via an unused wire in the engine bay, like the purge solenoid, then inside the diypnp, jump that pin on the connector board to pin #1 as outlined above.


the mapdaddy will actually take more effort installing, as you'd have to mount it in the proto area and run more than a few wires to make the connections necessary.

Thanks for the correction/clarification!

I THINK his first sentence should have read:
"Unfortunately, the MS2 firmware code can only read the one set of designated map sensor input pins located on the main board."

Where the sensor is actually mounted or how it feeds the said pins doesn't matter. Correct?


Regarding soldering in the MPX5700: you're proposing fully un-soldering the 4250 and resolding the 5700 in the same location, correct?

In the case of the external/3Bar, when I jump the new signal wire to pin #1, am I again fully un-soldering the 4250 in this scenario as well?

Sorry for the remedial questions. Thanks again.

Conclusion. Here're the exact steps I took:

1. Clipped existing the gold metal lead that was providing the input from the existing 4250 to mega squirt board.
2. Soldered a wire to the end of the metal lead (the side still connected to the board, not the 4250).
3. Soldered said wire to an un-used pin on the DIYPNP adapter board.
4. Soldered the three wires coming from the GM 3 Bar map sensor, to their respective wires feeding into the OEM ECU connector (5Vref, Sensor Ground, and my new Map Sensor input that uses the Purge Solenoid wire).

The 4250 is still attached to the board, seemingly bothering no one. In addition to adjusting the mapsensor settings in TunerStudio, the car also required updates to the fueling (Fuel VE table).

As always, thank you to Braineack and others for the helpful guidance.