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You do realize thats 58 psi right? I mean, theres nothing wrong with using it but a 3 bar will suit you just fine and you wont have to ask these questions.
 

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Discussion Starter #3
You do realize thats 58 psi right? I mean, theres nothing wrong with using it but a 3 bar will suit you just fine and you wont have to ask these questions.
It's actually 45psi as 1 bar is atmospheric pressure.

I would prefer a 3 bar, but you can't get a motorola 3 bar map, and there the cheapest, 2.5 bar isn't enough.
 

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Ricky i run a motorola 3 bar, the scaler for a motorola 3 bar part number 12223861 is 628 and the offset is 0 , you can get them from xenocron here http://www.xenocron.com/catalog/3-bar-map-sensor-kit-gm-p-195.html. be warned that GM actually makes 3 different 3 bars and each uses a different scaler and offset. the part number i listed above is the one i use.
Here is how to calculate the scalar and offset for a MAP sensor.

1. Find the minimum and maximum voltage and absolute pressures.

2. Convert the pressures to mbar.

3. Subtract the minimum and maximum voltages to find the range, then do the same for the pressures.

4. Divide the pressure range by the voltage range to calculate the scalar.

5. Multiply the minimum voltage by the scalar to calculate the offset. Note that a positive voltage gives a negative offset.

Example for a 3.5 bar MAP sensor:

1. For a 3.5 bar data sheet:
0.5V @ 0 kPa (absolute)

4.5V @ 345 kPa (absolute)


2. 345 kPa = 3450 mbar.

3. Voltage range = 4.0V, pressure range = 3450 mbar.

4. 3450 / 4.0 = 862.5 = scalar

5. 862.5 x 0.5 x -1 = -431.25 = offset

So scalar = 862, offset = -431

Plug in the minimum and maximum voltages to check your work:
0.5V x 862.5 - 431.25 = 0 mbar @ 0.5v

4.5V x 862.5 - 431.25 = 3450 mbar @ 0.5v
 

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Discussion Starter #5
Ricky i run a motorola 3 bar, the scaler for a motorola 3 bar part number 12223861 is 628 and the offset is 0 , you can get them from xenocron here http://www.xenocron.com/catalog/3-bar-map-sensor-kit-gm-p-195.html. be warned that GM actually makes 3 different 3 bars and each uses a different scaler and offset. the part number i listed above is the one i use.
Here is how to calculate the scalar and offset for a MAP sensor.

1. Find the minimum and maximum voltage and absolute pressures.

2. Convert the pressures to mbar.

3. Subtract the minimum and maximum voltages to find the range, then do the same for the pressures.

4. Divide the pressure range by the voltage range to calculate the scalar.

5. Multiply the minimum voltage by the scalar to calculate the offset. Note that a positive voltage gives a negative offset.



Example for a 3.5 bar MAP sensor:

1. For a 3.5 bar data sheet:
0.5V @ 0 kPa (absolute)

4.5V @ 345 kPa (absolute)



2. 345 kPa = 3450 mbar.

3. Voltage range = 4.0V, pressure range = 3450 mbar.

4. 3450 / 4.0 = 862.5 = scalar

5. 862.5 x 0.5 x -1 = -431.25 = offset

So scalar = 862, offset = -431

Plug in the minimum and maximum voltages to check your work:
0.5V x 862.5 - 431.25 = 0 mbar @ 0.5v

4.5V x 862.5 - 431.25 = 3450 mbar @ 0.5v
Does you's read accurately? The problem is with that is getting the voltages for the pressures.

I didn't know the GM was a Motorola?
 

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you will never get exactly the same between your boost gauge and your map, and the fact is once its tuned correctly it really dont matter what the map thinks equals 12 psi ect ect, just dont change scalers and offset settings once tuned of your tune will be screwed. here is a PDF with the specs of a ton of map sensors including most of the GM ones.http://www.plxdevices.com/AppNotes/PLXApp013.pdf oh and no mine dont read correct becuase i set it as a motec 3 bar when it got tuned. however like i said above it dont matter unless your map sensor is your only means of seeing how much boost your running.
 

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From every thing i know motorola makes GMs map sensors. either way the voltages arent hard to find out, all you need is a accurate pump and find out the voltage at 0 and at max psi.
 

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From everything I know, GM MAPS suck vs motorola (freescale from here on) when it comes to reading vacuum. Some GM's need the entire vacuum columns retuned, while almost all freescale sensors are as linear as you can get with a sub-$100 sensor.

BTW they do sell the 3bar, just not on ebay for under $15/shipped. They stopped offering the 3bar as a sample long ago because of abuse.


http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=MPXH6300AC6U-ND

The above link is to a Freescale 3bar, same size/port as the auction listed. It comes to ~$19/shipped. You can also use that datasheet to find the values needed for that above formula.
 

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Don't the omni/hondata map sensors and the motorola 4 bar map sensors share the same settings in hondata s300? They do in ectune and crome.

The omni sensor is nice, but I mean I paid 10 dollars for a motorola 4 bar,and had to solder 6 wires, so I saved 119.99 dollars + shipping.I always recomend the motorola map sensor to the diyer.It's a pain to solder the pin but it's really not that hard.If anything the 4 bar xenocron sells is only 45 dollars and already soldered and all you have to do is splice it into your wiring.Simple.If i had lots of cash to blow and wanted my bay to look nice by not having another sensor I would have got the omni.
 

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Discussion Starter #12
you will never get exactly the same between your boost gauge and your map, and the fact is once its tuned correctly it really dont matter what the map thinks equals 12 psi ect ect, just dont change scalers and offset settings once tuned of your tune will be screwed. here is a PDF with the specs of a ton of map sensors including most of the GM ones.http://www.plxdevices.com/AppNotes/PLXApp013.pdf oh and no mine dont read correct becuase i set it as a motec 3 bar when it got tuned. however like i said above it dont matter unless your map sensor is your only means of seeing how much boost your running.
Thanks for that.

I know what your saying, but it saves time and i wouldn't have to retune as much low down if i can get it set correctly.

Not sure which to buy now.
 
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