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Location:
Auckland, New Zealand
Registered:
October 2002
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1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 20:18
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Ive been going over this in my head for a couple days and was wondering if anyone here could shed some light on the matter for me.
OK - so NA cars come with 1 bar MAP sensors and most turbo cars come with 2 car ones (some with 3 bar).
Now all a MAP sensor does is sense the manifold pressure and convert this into a voltage and output it to the ECU which then looks up values in a table and supplies fuel and timing accordingly.
So how do 1 bar and 2 bar MAP sensors differ? Now im unsure about what range of voltage output to expect (anyone know?) but would i be correct in thinking that a 1 bar MAP outputs say 0-5v on a certain (possibly linear?) scale, and a 2 bar sensor say puts out 0-10v on the same scale.
Or, is it that these 2 sensors output the same voltage range, say 0-5v, but the scale is different (yet possibly still linear)?
Can anyone shed some light on this?
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Location:
UK
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 21:06
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Theyre all 5volts (well,most of them) All that happens is the output voltage is halved on a 3bar as opposed to a 2 bar.
Ie 1bar pressure one a 2bar map=5v. 1bar pressure on a 3 bar map=2.5v.
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Registered:
June 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 21:56
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HedgeHog has it right a 2bar bassically halves the calibration ie
1 bar pressure on a 1 bar sensor gives 5 volts.
1 bar pressure on a 2 bar sensor gives 2.5 volts.
2 bar pressure on a 2 bar sensor gives 5 volts
1 bar pressure on a 3 bar sensor gives 1.67 volts
2 bar pressure on a 3 bar sensor gives 3.34 volts
3 bar pressure on a 3 bar sensor gives 5 volts
this is only a rough guide there are some curves around for the GM sensors if you search.
Roger
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Location:
UK
Registered:
May 2002
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I supported Toymods
Location:
Northern Beaches
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 22:42
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ok a question just off to the side, but if ive got a microtech and want to go turbo, currently n/a, do I need to get a new MAP sensor or is there a way to trick it or something to handle to boost?
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Location:
UK
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 22:55
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no.. you need a new one.. you cant turn a 1bar into a 2bar.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Wed, 12 March 2003 23:35
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You can dodgy it by putting a bleed on it but this convenience comes at a cost. I am guessing that if you are using a Microtech, this is your primary sensor for calculating airflow and density. In this case, putting a bleed on it could stuff up your fuel metering.
If you do have an aftermarket ECU though, just get any old 3bar map sensor and chuck it in. Tell the computer the different map values and away you go.
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Location:
UK
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Thu, 13 March 2003 00:58
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That just defeats the fuel cut, it doesnt allow you to measure the increased pressure.
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Registered:
June 2002
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I supported Toymods
Location:
Northern Beaches
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Sun, 16 March 2003 20:46
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where whould you get any old 2 or 3 bar map sensor? and how much are they worth?
is it more accurate to run a 2 bar one if you are only going to be running say 6 or 7 psi, but in the long run might run more if get gze bottom end.
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Location:
Auckland, New Zealand
Registered:
October 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Sun, 16 March 2003 20:59
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Ribbo: - I imagine any old wrecker - here in NZ we have "pick a part" where u take yr own tools and yank the parts u want and its way cheaper than regular wreckers - look for a fact turbo car - sat a startlet GT for example - it should have a 2 bar sensor. You will then need to retune your microtech because the signals it will be getttin fed form the MAP sensor will be half the voltage (2 bar) that they used to be.
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I supported Toymods
Location:
Northern Beaches
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Mon, 17 March 2003 06:26
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cool thanx
the sensor is in the computer isn't it? Is it hard to change the map sensor in the computer?
ive got a hose running from inlet manifold to computer
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Location:
N.S.W
Registered:
May 2002
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Location:
UK
Registered:
May 2002
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Registered:
June 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Tue, 18 March 2003 03:26
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Twinky,
If your friend has no map sensor where there is supposed to be one. Yes the car would run like shit under any load, and could cause serious engine damage. Don't no much about the 4AGZE engine but if its map sensored, get one in there the results will be amazing 
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Location:
North Sydney
Registered:
May 2002
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Re: 1 bar vs 2 bar MAP sensors?
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Tue, 18 March 2003 07:18
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Ribbo if your going Microtech you don't need to buy a MAP sensor,
its comes with one internally.
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