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Subaru factory map sensors, V1-2 and V3-6

Reuben Horsley

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Sorry to bother, but I had very little results with my googling on this matter

I was always under the impression V1/2 map sensors were a lower reading sensor, than V3-6. Something like V1-2 is a 2.5 bar, and V3-6 was 3 bar. Forum posts about factory map sensors elsewhere on the net suggest this. But in all the link documentation I've seen, they reference all early map sensors, that is V1-6 as maxing out at 17.5 or 18 psi. This is contrary to what I do know of the V3-6 sensors, as they limit, or hit factory boost cut around 22psi... And I know V1-2 sensors are very much incompatibly with V3-6. Does anyone have any clarification on this?

Specifically I'm dealing with a G4 on a built motor, in a V1 WRX. It still has the factory older MAP sensor, and I have a V4 map sensor and plug I can wire in, to get me reading up to 22psi. I would also need to know what calibrations to enter for this map sensor, I've not been able to find info on that either (call me useless if you must).


Thanks in advance!

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Ok, weird. So I guess my next answer is what trickery do the V3-6 ECU’s use to read MAP up to 22psi? Even my V4 STi motor in my GTB does 19psi daily on a stock 6S ECU (Been dyno’d, it’s safe)

Sorry btw, not being stand-off-ish here, I’m just a bit confused cause this is the first time I’ve personally come across this contradiction, just trying to reconcile what I know with this data...

edit: oh I see it there, 18psi... above atmosphere... does this account for the difference here? MAP vs MGP?

To date my tuning experience has been with possum links, this is the first time I’ve messed with a G4, The ol possum link presents MAP as MGP is on the G4.

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Very early ones are only around 1.3 bar positive pressure ?

I did test a MY97/98 sensor years ago and although it can read to close to 2 bar positive.....it is only linear to around 1.5bar...between 1.5 and 2.0 it is not linear so unless a custom scaling is in place, do not trust it in that range with a generic A-B scaling.

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