MAP readings vs. boost
Instructor
Joined: May 2002
Posts: 168
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From: Wichita KS
Re: MAP readings vs. boost (diynoob)
sure there is, except my map maxes out at very low postive boost(forgot what the max reading is) so it cant be used to graph boost vs rpm or anything usefull. The ecm uses speed density mode after map is maxed?!?!?!?!?
Melting Slicks
Joined: Mar 2002
Posts: 2,931
Likes: 2
From: Tx
Re: MAP readings vs. boost (VortechC5)
Yep, the stock MAP is useless for reading boost. You can put on an extra 2bar map sensor (the ones from turbo V6 motors...) and read data from it, but you can't just replace your existing sensor as the computer is specifically calibrated for its ouput voltage.
I think you guys are a little confused about your terminology though (or I am).
Speed density is what is used when the MAF fails (not when the MAP maxes). MAP is just an axis on the VE table and the computer will hapily stick with the max reading under boost.
I think you guys are a little confused about your terminology though (or I am).
Speed density is what is used when the MAF fails (not when the MAP maxes). MAP is just an axis on the VE table and the computer will hapily stick with the max reading under boost.
Thread Starter
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From: http://www.mphparts.com 800-364-1975
Re: MAP readings vs. boost (diynoob)
Thanks guys. I'm confused why the MAP isn't accurate -- I thought 1psi was about 2inHg. So if the MAP sensor maxes out at 100ish, why isn't it accurate?
Is there atmospheric pressure that the MAP sensor is already reading that is causing it to be out of bounds with an increase in boost? I am at sea level so that should be about 14.7psi or roughly 30inHg which should leave plenty of room on the upper bound. :confused:
[Modified by diynoob, 11:53 AM 3/5/2004]
Is there atmospheric pressure that the MAP sensor is already reading that is causing it to be out of bounds with an increase in boost? I am at sea level so that should be about 14.7psi or roughly 30inHg which should leave plenty of room on the upper bound. :confused:
[Modified by diynoob, 11:53 AM 3/5/2004]
Thread Starter
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From: http://www.mphparts.com 800-364-1975
Re: MAP readings vs. boost (diynoob)
ttt
I am guessing from the post above about getting a 2 bar MAP that the stock MAP sensor is 1 bar or a max of 14.7psi read-out?
I am guessing from the post above about getting a 2 bar MAP that the stock MAP sensor is 1 bar or a max of 14.7psi read-out?
Melting Slicks
Joined: Mar 2003
Posts: 3,116
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From: Macomb MI
Re: MAP readings vs. boost (diynoob)
Sensors are in Bar..
Which mean absolute Zero is actually Vacum. 1 Bar is it average atmosphere (Baro etc) or 14.7psia.
So, A 1 bar sensor is good to 0psi or atmoshpere
A 2 bar is good to 14.7psi
a 3 Bar (Turbo V6) is good to 29.4 psi
Phil
Which mean absolute Zero is actually Vacum. 1 Bar is it average atmosphere (Baro etc) or 14.7psia.
So, A 1 bar sensor is good to 0psi or atmoshpere
A 2 bar is good to 14.7psi
a 3 Bar (Turbo V6) is good to 29.4 psi
Phil
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Thread Starter
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From: http://www.mphparts.com 800-364-1975
Re: MAP readings vs. boost (dads01dream)
:crazy: I need to sit down. :lol: Hopefully, I'll learn something here if I can stop seeing all these stars.
Melting Slicks
Joined: Mar 2002
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From: Tx
Re: MAP readings vs. boost (diynoob)
It is sometimes confusing. People often say they are running 2bar and they mean 30psi, but 2 bar for a map sensor is only 14.7 psi.
The thing to look for is the word absolute. If it has absolute in it like MAP (manifold absolute pressure) you are starting at absolute 0 and not sea level.
The thing to look for is the word absolute. If it has absolute in it like MAP (manifold absolute pressure) you are starting at absolute 0 and not sea level.
