Ok, so after some more reading last night & this morning, I thought I would make note of what I have found for future reference. If it turns out that what I have read to be correct, it could be use to someone else one day.

It seems the MAP sensor is there for 2 reasons

1. Boost control - along with the boost solenoid.
2. Boost cut.

Anything over 1.15 bar will cut fuel to the PFC with the version 1 MAP sensor, as this is the upper range of the instrument.

Voltages scaling on both MAP sensors is from 0 - 5V. 5V on the version 1 & 2 sensors in WRX's seems to be 1.15 bar (maximum the MAP sensor can read) . 5V on Version 4's MAP sensor Part #22012AA090 (not sure about version 3's) is 1.5 bar (I think).

The potential issue is putting a version 4 MAP into a version 1 ECU. There is a discrepancy of what a 5V reading actually is on the PFC (I don't think you can change the internal PFC calibration for voltages?) between the 2 MAP units & as such the Power FC will not read boost correctly. Not that this really matters if you have a standalone boost controller, but it does matter if you want to use the PFC's boost readout to log boost pressures through the power PFC / FC Datalogit & or, see what maximum boost got up too.

Both these below statements are a guess, but you should get the idea. I'm trying to explain what the PFC ECU will see with 1.15 bar manifold pressure with the 2 different sensors installed.

Version 1 MAP sensor on a Version 1 PFC ECU

Actual manifold pressure = 1.15 bar. Which on the version 1 MAP sensor is 5V - This 5V signal then corresponds to what the ECU has in its settings for what a 5V signal is (how it has been calibrated) to display the boost pressure. 5V = 1.15 bar, 4v = 0.9 bar etc....

Version 4 MAP sensor on a Version 1 & 2 PFC ECU

Actual manifold pressure = 1.15 bar. Which on the version 4 MAP is say only 4 volts. This 4V signal then this corresponds back to the PFC's internal calibration settings for what 4V means, which may only read .8 bar, giving a false reading as to what boost pressure the car is actually running in the manifold. 5V = 1.45 bar 4V = 1.15 bar etc...

I don't see this as a good idea. As I mentioned before, I think its good to know what the actual manifold pressure is.

How to get around this issue? How do I put more boost into the car safely?

The PFC has its own boost control system (additional parts required), which does not look at the Subaru MAP sensor (once you turn on boost control kit in the settings menu), but has the ability its plug its own map sensor & boost solenoid into the side of the ECU to control boost pressure & bypassing the Subaru system completely.

I don't need the boost solenoid part of the kit, as I have a stand alone boost controller. The MAP sensor is good to read up to about 3 bar (1.8 manifold pressure + atmospheric pressure) & more importantly, give the correct reeding of what pressure is inside the manifold.

I have not tried any of this yet, but will do next Thursday when I get home. The MAP sensor that plugs in the side of the ECU is only $50 (not the proper Apexi one), so I intend to give it a go to see if it works. Fingers crossed it does & I will report back. I only want to get to about 18 psi, but this is just out of the reach of the standard MAP sensor I have in there now.

If any of the above is incorrect, could you please let me know & I will change it to make it correct.

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Cheers,

Simon.

at such low boost levels, you overcome the boost control with just a simple bleed valve.

comes with its risks, but this is a track-hack afterall.

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Long live the WRC

What's the limit of the 99/00 map sensor?

I've seen in excess of 1.8 bar through my stock map, hence why I ask.

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for a my99/00 sensor motec document scales 0kpa as 0.732v and 240kpa (1.4bar) as 4.267v

anything above 4.5/below 0.5 should normally be considered an error state/uncalibrated, so as long as you have it plotted in the table, you have a bit of room to work with.

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Long live the WRC

It is only a track hack & I understand this Stace, but I want to try and monitor my boost pressures through FC Datalogit. I want to start to learn about car tuning. Bleeding off pressure to the MAP sensor will not show true boost readings on the PFC & hence the data I collect will not be true.


The map sensor which can read higher than the one I have Rossco Part #22012AA090 is "supposedly" capped at 1.45 bar.

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Cheers,

Simon.

Cheers, Stace.

I just had a squizz at some of my logs, 1.71 bar = 4.87 volts on my map sensor.

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[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]

Rossco,

Is there a way to change the voltage scaling of the ECU to the pressure the manifold is reading using FC datalogit?

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Cheers,

Simon.

finding this hard to believe

Maybe you'll find this more believable then?

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[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]

No mate, there's not by default, but you could set up an auxiliary input to the datalogit to monitor & log a 3 or 3.5 bar sensor.

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[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]