im sorry if this has been covered already, if it has can someone just give me the link?

ive read all the newbie threads and im still confused on what a bar map sensor is. i know there are 1, 2, and 3 bar map sensors, but thats about it. what do they do, or what is their purpose. i would appreciate it if someone can help me. thx.

 

Bar is the amount of pressure.
1bar~14.7 PSIa

a 1 bar can only read 14.7 psia or 0psi boost
a 1.8 bar (stock honda) can read .8 bar 11.76 psi of boost
a 2 bar can read 14.7
a 3 bar can read up to 29.4
a 4 bar and so on.

Get it?
For a stock honda staying around 0-12psi of boost, a stock one is fine.

 

o, ok. so the bar map sensors are just so it can read higher boost? like the stock one can only read 0, and 1.8 =14.7 and so on.

k got that. but what happens if i run like 15 psi, on a stock bar map?

 

You get CEL's Because the ECU will think something is going wrong or the sensor is malfunctioning.

 

No.

1 bar is 14.5 psi. That 14.7 ---- is called atmospheric pressure, which is something different.

Stock Honduh MAP sensor can at no time read as much boost as you claim. Honduh MAP 85-91 reads 9.25 psi, 92-until reads 10.65 psi. Hyundaidata claims 11.3, when questioned Dougie said they read all over the place, but all I've seen is a consistent 10.6x psi limit.

Lets compond the situation and bring into discussion quality control and calibration.... stock Honduh MAP sensors are pretty well calibrated from the factory. GM 3 bar, for example, have a +/- 3% variance from "ideal," which means your GM 3 bar can read as low as 26 psi before maxing out and as high as 32 psi. Welcome to miscegenated GM garbage, and the reason why you always retune when switching GM junk sensors...

With stock ECU? Sure. You'll hit limp homo mode long before you hit past what the MAP sensor can read, much less 15 psi. Now, try to run 15 psi on stock MAP sensor with an ECU running boost code - depending on the MAP sensor you're running, the ECU thinks you're running 9.25-10.65 psi. Welcome to too little fuel, too much ignition.

Boost cut is your speshul friend!

 

Oh, sorry your right 14.5 is 1 bar, I just finished writing a Thermodynamic midterm so that threw me off.