Hi Guys,

I have recently purchased a haltech 3 bar map sensor and cannot find the formula anywhere, I live in sydney Australia so I know my AP is 14.7 PSI.

All i know is the following from Haltech:
callibration is: 0V = -14.PSI
4.717v = 29PSI

Can someone please help me work out the formula I need to log boost and do v7 PSI based boost control.

Thanks

Dale

 

Its roughly the same as a jdm 3 bar map sensor then use that as a base and just tweak it as needed with the load column you should be fine that way.

 

ok I will try that. hopefully I can get it working, the load column is the first 0.xxx digits isnt it? or is it the -14.x?

 

anyone else have any input?

 

https://www.evolutionm.net/forums/ec...equations.html
i still dont understand it but check it out

 

Hi Guys,

I am really stuck, I have tried the JDM equation and the car only reads -6.4837 continuos.

I also tried the GM equation and the same thing happens. Is there rom mods I need to do to tephra v7? or does someone know the correct formula? I am stuck and would really appreciate a GURU help.

I found this graph that shows the linear line if it helps.
http://hhscott.com/93tmv/3-bar_map.htm

 

Hey guys,

to get it to zero, i used the JDM formula, removed the -14.5, and checked the value it showed it was out. i got this = 15.67107
so i put the formula below in an it red zero on ignition. I took the car for a drive and checked what boost it reached, I know by my boost guage im on 19/20psi and this showed 19/20psi to. Could this formula be right?

0.19347*x-15.67107

Please let me know if this is right, any guru's would appreciate your input.

 

really knowone has input??? I just need to know if this is the right formula, or if i even can use it?

 

Don't be surprised if on the weekends responses are slower :P

Looking at your measured values i came up with something different.
0.1809*x- C whatever air pressure is for you C can be 14 depending on altitude but is normally 14.5.

This formula was made on the assumption that 4.717 = 29psi and 0v = -14psi is actually right.

Its still super close to the formula to the JDM 3 bar if you were getting only a constant number something was wrong with the formula you entered. For example you can't enter a formula like this 1.6x-14.5. This fails in my evoscan because evoscan excepts to see a "*" symbol for multiplication and treats 1.6x as a word so the word equals nothing. however 1.6*x would equal some number. So the corrected way is always use * for the multiplier.

 

agree with that. i think the x symbol is ignored but shown so we visually get its a multiplication at that point

 

Thanks Roadspike, I will try this tonight and let you know.

 

update?

 

I didnt have time last night, I will be doing tonight and letting you know.

 

Hey guys,

Put this in and at idle the car is showing -6 where my boost guage was showing -11 or so. Is this right?

I took a screen shot attached to show the problem.

 

Is your gauge in in/hg for vacuum? If so its really close if nothing else maybe off by .5.