GM Map Sensor Gain/Off Set
- Thread starter lazaris
- Start date
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
Interesting application. It would also show any crankcase pressure. Here is the transfer function for the GN 2-bar MAP, which also matches the small form factor 2-bar sensors (09350899 & 16235939):
Vout = Vref * (KPa * .005 - .04)
Vref being the power supply to the MAP sensor voltage (typically 5.0 or 5.1 volts).
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Vout = Vref * (KPa * .005 - .04)
Vref being the power supply to the MAP sensor voltage (typically 5.0 or 5.1 volts).
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RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
I'm going to use the stock 2 bar GM map sensor. I have to input the gain and off set values in the XFI to make it read correctly.
RmvBfrFlght
Well-Known Member
- Joined
- Sep 28, 2007
OK, the transfer function I posted is correct for that MAP sensor. Just need to swap it around to go from voltage to KPa.
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1 Bar will not allow for Boost pressure, only vacuum.
Personally, I feel that it is a relative value that we are looking to see, weather C.Case pressure is increasing or staying stable during a run, and being able to compare it to when you are not using a pump.
That being said I run a LT1 pump strickly to control oil leaks, not for power and I can clearly see a change in vacuum during a run. I use a 2 bar
Adrian
Personally, I feel that it is a relative value that we are looking to see, weather C.Case pressure is increasing or staying stable during a run, and being able to compare it to when you are not using a pump.
That being said I run a LT1 pump strickly to control oil leaks, not for power and I can clearly see a change in vacuum during a run. I use a 2 bar
Adrian
Thank you. Will those settings read in inches of vacuum or pressure?2bar Map sensor:
Sensor Gain: -12 Sensor Offset: 30 Sensor High: 30 Sensor Low: 0 Decimal Places: 0
my contribution for the week.
Yes I know, I was curious as to Adrians settings since he didnt say how it read and they were different from yours.
Lol. Thanks again Cal.
Hey Guys, sorry for the response,
Yes the numbers I listed were originally from Cal Hartline. They are in InHg and like Cal said, InHg are positive values.
I run a LT1 pump and I see 2 InHg of vacuum when the pump is on, and it stays stable when it is on.
I activated it with one of my Aux outputs and that's it.
I am logging from the passenger side valve cover and pulling from the drivers side.
I never really took the time to tweak the sensor so it is perfect, but it is on my list of things to do over time, but to me honestly it only needed to give me a relative reading and I can see if I am getting major blow-by.
I will say that I ran the car once with the pump on and once without and the log did show that without the pump I was getting more crankcase pressure.
A
Yes the numbers I listed were originally from Cal Hartline. They are in InHg and like Cal said, InHg are positive values.
I run a LT1 pump and I see 2 InHg of vacuum when the pump is on, and it stays stable when it is on.
I activated it with one of my Aux outputs and that's it.
I am logging from the passenger side valve cover and pulling from the drivers side.
I never really took the time to tweak the sensor so it is perfect, but it is on my list of things to do over time, but to me honestly it only needed to give me a relative reading and I can see if I am getting major blow-by.
I will say that I ran the car once with the pump on and once without and the log did show that without the pump I was getting more crankcase pressure.
A
Actually the numbers you listed were different from Cal's. The Gain and Off-Set values are reversed.
