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Discussion Starter · #1 ·
I am going to be running a d16a1 turbo Setup. I am going to get my ecu chipped but i hear people talking about 2 or 3 bar map sensors. CAn someone explain whats going on here. or tell me where i can go to find out.
 

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the bar map sensor will alow the ecu to read boost, meaning that instead of hacking up the signal all to hell you can properly tune for different boost levels, based on the map sensor signal...if you plan on running over 10 psi from whatever turbo you plan on using you'll need either a 2 bar or 3 bar map sensor...your stock map sensor will only read to i believe ~10 psi...anything passed that and it will throw a CEL...
 

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bar is a measurement of pressure just like psi is...and just like said above, 1 bar = 14.??? psi...that's all it is...so a 2 bar map sensor will read up to 2 bars, or 29.???, and so on so forth...
 

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Discussion Starter · #7 ·
O ok. since im running an obd0 you think i will have a problem finding a 2 Bar..
Do you have to wire it up differently in the harness?? Or what..
 

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that 2 1/2 bar boost can not read 30 pounds of boost you need to take into the negative boost pressure otherwise known as vacuum. so it will not ready 30 pounds only about 22lbs.
boost is the pressure above the barometric pressure - manifold vacuum is the difference between the pressure inside the intake manifold and the barometric pressure and is consequently less than the barometric pressure - at wide open throttle, vacuum is essentially zero - you cannot have boost and vacuum at the same time
 

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that is 30 psi TOTAL...in a boosted motor i believe you will read vacuum when the motor is out of throttle (ie...when you down shift the turbo should not be producing any boost because you do not push the gas peddle down, instead the motor is going to try and pull in a little amount of air but since the turbo is not being spooled there will be a vacuum within the manifold)...if this is wrong please someone correct and explain because this is how i understand it...and frankly i like to have the correct information :)
 

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that is 30 psi TOTAL...in a boosted motor i believe you will read vacuum when the motor is out of throttle (ie...when you down shift the turbo should not be producing any boost because you do not push the gas peddle down, instead the motor is going to try and pull in a little amount of air but since the turbo is not being spooled there will be a vacuum within the manifold)...if this is wrong please someone correct and explain because this is how i understand it...and frankly i like to have the correct information :)
you are correct - when the engine is idling with the throttle closed, the pressure outside of the intake manifold is 1 Bar (average of 14.7psi at sea level) and inside the manifold, the engine is trying to suck in air creating a vacuum - the vacuum will be somewhat less than 1 bar negative because the engine needs some air in order to run - it gets this air either thru holes in the throttle plate or a bypass hole in the throttle body - as you open the throttle, the air outside the intake manifold tries to rush in thru the throttle body from the area of high positive pressure to the area of low negative pressure - when this happens, the vacuum drops - when the throttle plate is fully open, the pressure inside the intake manifold equals out with the pressure outside the manifold and you have no vacuum (actually there is still a slight vacuum because of obstructions like the throttle shaft, etc.) - with NA engine, this is as far as you can go - air pressure equal outside and inside the intake manifold at WOT - when you boost it, you are increasing the pressure inside the intake manifold so that it is higher than the pressure outside - thus, if your boost is 10psi, the actual pressure inside the manifold is 10psi plus 1 Bar - in that case, at sea level, you would need a MAP sensor that could sense 10+14.7 or 24.7psi (2 Bar sensor would be about 29.4, if everything was perfect) - if you were boosting anything above 1 Bar (14.7) then you would need a 2.5 or 3 Bar MAP - as long as there is any boost, even if it was only 2psi, there would be no vacuum - if you look at a boost gauge, you will see that it reads something like 0 up to +30psi boost and on the opposite side 0 down to -30psi vacuum - you either have boost or you have vacuum or if everything was just right you could be neutral
 
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