Omni 3Bar MapSensor help
#1
Evolving Member
Thread Starter
Omni 3Bar MapSensor help
Currently I am running the latest Tephra 96530706 V7 Rom on my car, using Load based boost control with a 3 port solenoid and everything is working great.
I recently purchased the Universal Omni 3Bar map sensor http://www.omnipowerusa.com/product.asp?P_ID=158 and first checked with MrFred that it would work with direct boost control.
I know have it installed in the car, but I am still using the Load based boost control.
My first step it o make sure that I can get the map sensor to log the correct boost in Evoscan.
A few questions.... more to follow
1.) In Evoscan, do we use the same formula for the 4 Bar Map sensor? as posted over here. in MrFreds post "Omni 4 bar MAP sensor ROM compatibility settings for USDM Evo 8/9"
I had to change the formula to make allowance for my local elevation which is 5500 feet, This is my current formula Evoscan.
0.2369*x-12.0
When I log boost in Evoscan, while doing a WOT 3rd gear log, and then comapre it to my reading on my boost gauge I get strange results.
My boost gauge peaks at 1.6 Bar (23 PSI) but I am logging just over 30PSI at peak boost in Evoscan.
Am I using the correct formula for the Universal Omni 3Bar sensor?
Thx for looking.
I recently purchased the Universal Omni 3Bar map sensor http://www.omnipowerusa.com/product.asp?P_ID=158 and first checked with MrFred that it would work with direct boost control.
I know have it installed in the car, but I am still using the Load based boost control.
My first step it o make sure that I can get the map sensor to log the correct boost in Evoscan.
A few questions.... more to follow
1.) In Evoscan, do we use the same formula for the 4 Bar Map sensor? as posted over here. in MrFreds post "Omni 4 bar MAP sensor ROM compatibility settings for USDM Evo 8/9"
I had to change the formula to make allowance for my local elevation which is 5500 feet, This is my current formula Evoscan.
0.2369*x-12.0
When I log boost in Evoscan, while doing a WOT 3rd gear log, and then comapre it to my reading on my boost gauge I get strange results.
My boost gauge peaks at 1.6 Bar (23 PSI) but I am logging just over 30PSI at peak boost in Evoscan.
Am I using the correct formula for the Universal Omni 3Bar sensor?
Thx for looking.
#2
Evolved Member
iTrader: (6)
You can't use the 4bar scaling for the 3bar sensor. According to the omnipower manual, for the 3 bar sensor:
P_kpa = 1.233*x + 1.110
If you want it in psi:
P_psi = 0.1789 * x + 0.1610
That's absolute pressure. If you want "boost", subtract your atmospheric pressure.
d
P_kpa = 1.233*x + 1.110
If you want it in psi:
P_psi = 0.1789 * x + 0.1610
That's absolute pressure. If you want "boost", subtract your atmospheric pressure.
d
Last edited by donour; Nov 26, 2009 at 10:09 AM.
#3
Evolving Member
Thread Starter
Thx , strange that mine never came with a manual.
#4
Evolved Member
iTrader: (6)
I don't think there is a pack-in manual that comes with any of the senors. Omnipower USA provides a calibration document here:
http://www.omnipowerusa.com/calibrations.doc
The information for the 3 bar sensor is on page 2.
d
http://www.omnipowerusa.com/calibrations.doc
The information for the 3 bar sensor is on page 2.
d
#7
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#11
Evolved Member
iTrader: (30)
The format of how the ECU is interpreting the MAP sensor data is actually 16 bit in the ECU and only 8 bit in the datalogging. So the ECU is dviding relative pressure with 1024 as the ultimate value not 256. This would mean on the absolute scale (since it is reading vacuum) that a 4 bar would be 1024/4 or 256 samples per bar for actual calculations. The 255/4 would be 63.75 samples per bar.
On the 3 bar this would be 255/3 85 for logging only. For calc purposes we'd be around 341.3 per bar.
Since there are quite a few of us running 28-29psi on pumpgas on larger turbos and many running over 29psi on racegas and E85 the 4 bar makes sense. Really if you arent going to go over 33, the JDM "3" bar (actually 3.25 or so) makes the most sense. But when you factor price and availability the 4 bar is equivalent in price, as available, and still allows for more in the long run.
On the 3 bar this would be 255/3 85 for logging only. For calc purposes we'd be around 341.3 per bar.
Since there are quite a few of us running 28-29psi on pumpgas on larger turbos and many running over 29psi on racegas and E85 the 4 bar makes sense. Really if you arent going to go over 33, the JDM "3" bar (actually 3.25 or so) makes the most sense. But when you factor price and availability the 4 bar is equivalent in price, as available, and still allows for more in the long run.
#12
Evolved Member
iTrader: (6)
The format of how the ECU is interpreting the MAP sensor data is actually 16 bit in the ECU and only 8 bit in the datalogging. So the ECU is dviding relative pressure with 1024 as the ultimate value not 256. This would mean on the absolute scale (since it is reading vacuum) that a 4 bar would be 1024/4 or 256 samples per bar for actual calculations. The 255/4 would be 63.75 samples per bar.
d
EDIT: Two-byte boost anybody? J/K.
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