subaru 96 v2.28 new map sensor fitting

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2ltrrabbit
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Re: subaru 96 v2.28 new map sensor fitting

Post by 2ltrrabbit » Thu Jan 09, 2014 11:30 am

Hi, any update on the mbarc and m settings.

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RickS
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Re: subaru 96 v2.28 new map sensor fitting

Post by RickS » Fri Jan 10, 2014 10:21 am

I will get some solid info from the software developers on this next week as they are all at the Autosport show at the NEC this week.

Now, I maybe gravely mistaken but the way that I have derived these figures in the past (and it seems not to dis-similar to the cals that I can find in the archive) is that you take the absolute boost that you want to run and multiply it by that magical computer nimber 256. So for your 1.4 Bar of boost, add 1 Atm to get an absolute figure and multiply by 256. Now subtract 10% to give a little 'safety headroom' and you should end up with a figure of 553. This is your 'm' value.

To obtain 'c' just enter a value which gives the correct atmospheric pressure reading when the sensor is open to the atmosphere pressure only. This will be trial and error as there is usually a little variation between sensors and the ambient pressure on the day that your calibration takes place. If you can't check the ambient pressure and don't have a barometer handy, then just assume a value of 1000 mBar; this will be near enough to get car running.

In the meantime, if you/anyone knows of a more accurate/detailed process, please post it here.
Best regards,
RickS

Ricey
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Re: subaru 96 v2.28 new map sensor fitting

Post by Ricey » Fri Oct 18, 2019 11:10 pm

Hi guys,
Bit baffled by this.
I have one cal with MAP mBar m set to 610 and MAP mBar c set to -101 and another cal (which runs my Prodrive gpN car fine) with MAP mBar m set to 315 and MAP mBar c set to 787.
Reading what RickS says in the last post on this thread and the values I have in the cals I have, does not seem to correlate with what he said in the second post:
"The 'MAP mBar M' is a multiplier and 'MAP Mbar C' is an offset used to scale the MAP parameter. It is used thus....
Air Pressure = ('MAP raw' x 'MAP Mbar m') + MAP Mbar C."
Using the above equation and assuming units of millibars (mBar) NOT pascals, kPa, bar or some other unit. Using a syringe to apply vacuum and pressure (respectively) to the MAP sensor with a boost gauge T'd in; at a MAP Raw reading of 58 I'm at about -0.3 bar gauge, at atmospheric I'm at MAP Raw of 83 and at 0.4ish bar gauge I'm seeing MAP Raw of 120.
These values equal about 700 mBar absolute for the 58 MAP Raw reading, atmos (1000mBar)for the 83 MAP Raw reading and 1430 mBar for the 120 MAP Raw reading. The only way I can get these number to equate using the about formula is the a MAP mBar m valuse of 12 and MAP mBar c value of 0.
This seems a country mile from the values in the base map (Subaru 99 v2.30) on the website or either of the cals I have here. Using the values in the base map I calculate 'Air Pressure' (in millibars?) of 38287, 54812 and 79269 for the MAP Raw values 58, 83 & 120 respectively - clearly this cannot be correct.
Doesn't seem to correspond to any other units (such as pascals) either?
What actually are the MAP mBar m and MAP mBar c options used for, is is used for scaling the Y axis of the fuel and ignition maps to the max boost pressure you want to run? Surely MAP min and MAP max do this?
This is where the last post by RickS is confusing, why would you use a value in bar when the option is mBar? And what does the maximum boost you intend to run have to do with what appears to me (from the second post) to be a sensor linearization calculation?
Do the 0-130 units in the Y axis of the maps correspond to MAP Raw values or are they (as I suspect) arbitrary 'GEMS' units?

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RickS
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Re: subaru 96 v2.28 new map sensor fitting

Post by RickS » Mon Oct 21, 2019 7:50 am

They are arbitrary units used by GEMS when they were building Units before my time.
This is the information given in the manual but I have forwarded your comments to our Technical Director to see if he can explain better.
Best Regards, RickS

Ricey
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Re: subaru 96 v2.28 new map sensor fitting

Post by Ricey » Mon Oct 21, 2019 10:35 am

Thanks. PS "about formula" should read "above formula" - autocorrect typo.

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Re: subaru 96 v2.28 new map sensor fitting

Post by Ricey » Mon Oct 21, 2019 10:47 am

I'm starting to think that that these settings only matter if WG Feedback is ON and you're using the Boost Target map (which seems a closed loop kind of boost control but with apparently no control over PID settings except possibly to the extent of the boost error table). That being so, the value for pressure still needs to be in mBar.

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Re: subaru 96 v2.28 new map sensor fitting

Post by RickS » Mon Oct 21, 2019 2:50 pm

An update from our Technical Director...

The Mbar C and M options only effect is to scale parameter Map Pressure, not Load. They do not affect the mapping in any way.
Subaru 96 has 17 load sites 0 - 160 standard map sensor 2.3 bar absolute as far as I can remember
Subaru 99 has 14 load sites 0 -130 standard map sensor 2.7 bar absolute as far as I can remember
Do contact us with specific sensor information, and we may be able to generate scalars to suit.

Richard Lloyd
Director

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