NB Boost sensor (Factory MAP sensor) calibration
 

Does anyone here have the NB factory map sensor calibration? I was looking at putting a MS3Pro module in the factory ECU case and the module does not come with a map sensor. I was wondering if anyone has used the factory map sensor with a megasquirt.

This would come in handy for anyone running in an autocross class where you cannot add/modify map sensors etc.

is your car n/a? cause it's just a baro sensor, it doesn't actually read boost

Yes, it will be a N/A only car. Thanks for the information too. I am in the planning stages of swapping in a VVT motor, similar to what I have in my NA Racecar. Going to be sweet to have the same 145hp, but with A/C and a radio as a daily driver!

There is no map sensor in these cars, only a MAF.

'99+ have a "Boost Sensor" mounted on the fender above where the evap canister is located.

MX-5 Miata Forum


https://www.miataturbo.net/attachmen...ine=1460152830

whaddayaknow, I stand corrected :). We don't have a boost sensor on NB's overhere, only on NBFL's. Never knew US cars had one.



https://www.miataturbo.net/attachmen...ine=1460155127

I was just getting ready to ask this same question. Anyone know the answer?
0V = X
5V = Y

@Reverant ?

The stock "boost sensor" is there as part of the EGR valve control loop.

--Ian

It will be re-purposed as a Baro correction Sensor.

I'll try and pull one off the parts NB around here and compare it to mine.

That would be kind.

However, if someone does not have the data already, I should do that work.

Figured I'd just put it on a tee with the MS and a vacuum / pressure source, plot a curve, calculate the calibration constants, and publish them. I think Thumpetto007 is going to need them as well.

Honestly, it might be a month before I get to it. So whoever gets there first.

0V - 15kPa
5V - 115kPa

really that's it? According the the manual the OE ECU uses it to adjust fuel trims in boost, so basically the ECU just knows it's in boost, but how much it doesnt care?

huh? N/A cars don't go into boost.
Unless you're talking bout the msm which also doesn't read in boost it just goes open loop and assumes urrythang is "ok"

no, the ECU uses it. On the MSM mazda even refers to is at the "BAROMETRIC PRESSURE (BARO)/MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR", and not just the BOOST sensors on the other NB2s -- but it's the identical sensor and plumbing.


https://cimg6.ibsrv.net/gimg/www.mia...2d1bc00f1b.png

There's references that it uses it for fuel trims. Looking for that now, but the ECU at least knows that car goes into boost -- what it does with that knowledge is beyond me.

Interdasting cause over the many years and years of the M-S folks looking into this, no one has ever been able to confirm that the MSM actually see's or records or references boost in any meaningful way. (as in, it actually see's the 6-8psi that it makes when in OL)

not sure. obviously the map sensor reads above atmospheric, it probably uses a combo of that plus the MAF voltage to figure things out. Doesn't the MSM even have an over-boost cut?

Overboost is set by load I believe which is maf voltage + rpm. If it's the same sensor, and the sensor reads to 115kpa only, even if it did use it I bet it would only be a CL/OL trigger. Which it's not, cause we already confirmed CL/OL is triggered by the TPS on those cars. I am open to be proven wrong, but you'll need some proof.

no you're probably right. it can basically see postive boost, but probably doesn't do much at all with it, just switches to a boosted map.

I'm going to plug in Rev's numbers. Likely within the week (schedule update) I'll have the MS at least temporarily hooked up to test spark and injector harness updates. At that time, I'll have a borrowed, hand vacuum pump and be able to compare the internal MAP values with this sensor's readings.

Note, Rev's values are quite close to the GM 1 BAR values, so if it is indeed a 1 BAR sensor, the numbers make sense.

MSM_MAP(psi)=7.811*(MAP_V)-5.764 @25°C and 250m above sea level



https://cimg4.ibsrv.net/gimg/www.mia...023bd90217.png

what are we looking at? Bluetooth/torque app?

Torque cannot read enhanced(extended, factory, etc) Mazda/Ford PIDs.

You need Ford IDS with VCM adapter or software/app with Ford/mazda factory PIDs

You look at Forscan for Android

Cool. So then it does reference map/boost? do you have a plot or log to show us?

In the current version Forscan shows boost( MSM_MAP(psi)=7.811*(MAP_Voltage)-20.464 ) despite PID name is MSM_MAP( MSM_MAP(psi)=7.811*(MAP_V)-5.764 ).
I will ask Forscan developers change the PID name in the next revision.
and it reads second IAT(after intercooler) on MSM(this is not actual for aftermarket ECU owners :) )

Well I stand corrected :)

Never saw that before.

what does this mean? I always use the 2nd AIT for MS3x MSM builds when the user doesnt want to install a GM AIT Sensor...

I am sorry, it is my poor English :(
I mean "Ability to read IAT2 via OBD2 is not important for aftermarket ECU owners"

oh okay, gotcha.

And for the empirical engineering
 

I started with that, with the MAP in the MS and the "Boost Sensor" connected together with a vacuum pump.

To get them to read together from 61 to 98 kPa, i ended up with these values:

0 = 3
5 = 119

Of course, I'm really only interested in 85 to 102 where I'm going be driving.

Boost Sensor Connected to tube from Manifold
https://cimg7.ibsrv.net/gimg/www.mia...341161bc5f.jpg

Tube from Boost gauge ready to be connected to vacuum pump
https://cimg8.ibsrv.net/gimg/www.mia...7c71781797.jpg

Low end: MAP = 69, Baro =68
https://cimg9.ibsrv.net/gimg/www.mia...d4a5bde641.jpg

High end: MAP = Baro = 98
https://cimg0.ibsrv.net/gimg/www.mia...683c72b8a3.jpg

Necro thread resurrection; does anyone know if there's a 2- or 3-bar sensor that is physically plug n play on the OEM harness? Rev has confirmed that the MS3 mini can read the stock baro sensor. I would prefer to run a short line from the IM and use this as a MAP with the on-board sensor on the MS3 acting as a baro correction device (yeah I am ---- like that).

The Baro sensor on that comes on the Miata is part of the pollution control system. It is called a boost sensor, but it is only a little over 1 BAR. I am using it for my Baro sensor. So no, you cannot connect it to the IM and use it for MAP. You have to do it the other way around. Use the onboard for MAP, and the other for baro.

Here is the pertinent thread on calibration

It might work on a naturally aspirated motor, definitely not on a turbo one.

If you really want to avoid running vacuum lines or additional wires through the firewall you could remove the OEM MAP sensor and install an off-board sensor (like the GM 3-bar one) in its place. You would need to adapt the wiring harness somehow, ideally by sourcing the proper connector to build a short adapter harness.

--Ian

@DNMakinson thanks! I am aware of that; this thread prompted my question, hence my post here.

Exactly what I was thinking; just wondering if there was any electrically compatible 3 bar sensor out there that would save me the "hassle" of building an adapter harness. Reasoning is that it would be cleaner/easier than running a vacuum line to the MS.

OK. I am pretty sure that there are (2) allowable external MAP sensors allowed on the MS3 Basic; but I don't know about the mini. Point being, that just because the mini can read the Baro, does not mean it can be mapped to the MAP input. Just not sure.

Good point (that I have not thought of); I was thinking that as soon as it reads that as input, it should be able to. Will report back once I find out (ECU sitting in a box for the past 8 months now)

What do you mean by "electrically compatible"? I doubt you'll find a 3 bar sensor that has the Mazda connector on it, if that's what you're asking.

You don't really care about the response curve (volts per unit of pressure) because you're not going to run it with the stock ECU, right?

The voltage supplied to the sensor might be an issue. I *think* the GM sensor takes 5 volts in, but I don't know what Mazda supplies to the OEM sensor. That might be an issue.

--Ian

Would like to avoid cutting the plug off the loom, but may just do that. Do not care about calibration, as indeed will be using a standalone ECU. Pretty sure the stock one is 5V, will verify and report back. Thank you all for your inputs!