Omni 4bar map sensor Plug and Play
Feb 12, 2009, 05:44 AM
#52
It appears to be a 10bit ADC, shifted right twice to become 8 bits.
So you have 0-1023 where 1023=5 to 5.1 V depending on what the supply rail is. Quantisation is therefore about +-0.05%, any other errors will be due to non-linearity of the ADC, often the accuracy is quoted as +-1LSB. Good enough not to worry about from an engine control point of view even with a 1V/bar sensor if using the 10 bit ADC IMHO.
So you have 0-1023 where 1023=5 to 5.1 V depending on what the supply rail is. Quantisation is therefore about +-0.05%, any other errors will be due to non-linearity of the ADC, often the accuracy is quoted as +-1LSB. Good enough not to worry about from an engine control point of view even with a 1V/bar sensor if using the 10 bit ADC IMHO.
Feb 13, 2009, 07:50 PM
#53
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Omnipower sensor
The 4 bar Omnipower sent me for testing only came with this information.
MIN = 0V
MAX = 4.8V
LOAD OFFSET = 0
SCALER = 4.0
SENSOR IS DEAD LINEAR WITH TEMPERATURE COMPENSATION.
Hope this helps some people out.
MIN = 0V
MAX = 4.8V
LOAD OFFSET = 0
SCALER = 4.0
SENSOR IS DEAD LINEAR WITH TEMPERATURE COMPENSATION.
Hope this helps some people out.
Feb 20, 2009, 10:19 AM
#55
I am in the process of getting the sensor going on 94170015 to try out the speed density. Here is my post from the speed density thread, as really, it's more relevant to this thread.
To add, according to Omnipower this sensor is not really a new sensor either. They are using a sensor that they have been using in the Honda OEM replacement sensors for the last couple years and have had excellent success with the reliablity of the sensors.
I'll try and put a few miles on it today to see if I get a CEL using the 3bar MAP test/EGR test settings.
I messed around with the map sensor, a voltmeter and a potentiometer today and was able to answer a few of my questions while also finding a small issue with the Omni-Power MAP sensor.
The map sensor did not work at first. After talking with Steve at Omnipower, we were able to get the problem resolved. It turns out that the sensor pin out is not the same as factory. You will need to swap the two outer pins on the MAP sensor harness connector. I would suggest ordering directly from Omnipower and asking about this so you will know in advance if the wires will need to be swapped as they said they will likely be changing this to the factory pin out. Omnipower was great to work with though and I will definitely recommend others to do business with them. IMO, this is the sensor to buy over the 3bar JDM sensor simply because of the extended range. A stock turbo on E85 can max out the JDM 3bar...
The ADC seems to be a true 0-5VDC input as there was a 0 count until ~10mV and 255 happened at 4.99 VDC on my handheld.
Scaling in evoscan was straight forward, but I'm still trying to sort out the scaling in logworks2.0. It seems that simply writing the equation in the protocol.xml file is not enough to get the logging correct? You need to go into the channel configuration in the logger (and dashboard if desired) and set the range to match the range entered in the protocol.xml file? I haven't verified this with a fresh log, but I was able to get a log that was not displaying correctly to display correctly after making this change.
I'm using (x-52)*0.2368 as my scaling in logworks to get gauge pressure in PSI. The -52 offset is the raw bit count I get at atmospheric pressure (84.77 kPa). I have done this because I feel that because the resolution is in 0.2368 PSI increments with the 4bar that the pressure measurements may remain more stable with this scaling. Atmospheric pressure usually sticks within that range, using the raw bit count instead of subtracting a particular atmospheric pressure may provide a more stable boost reading and was easier as all I had to do was input the raw bit count with ignition on, engine off. Something like x*0.2368-(atmospheric pressure) should also work for logging though if that's easier to use or provides more accurate numbers?
EDIT: I also loaded up the MAP test settings used on the JDM 3bar that Mrfred came up with for 94170015. I'm not real sure what these values do, so I have no idea if they will be effective on thsi sensor. I'll give it a shot though and report back. Reading the requirements of the EGR test to happen though, I wouldn't be surprised if my driving style never even lets these tests run.
The map sensor did not work at first. After talking with Steve at Omnipower, we were able to get the problem resolved. It turns out that the sensor pin out is not the same as factory. You will need to swap the two outer pins on the MAP sensor harness connector. I would suggest ordering directly from Omnipower and asking about this so you will know in advance if the wires will need to be swapped as they said they will likely be changing this to the factory pin out. Omnipower was great to work with though and I will definitely recommend others to do business with them. IMO, this is the sensor to buy over the 3bar JDM sensor simply because of the extended range. A stock turbo on E85 can max out the JDM 3bar...
The ADC seems to be a true 0-5VDC input as there was a 0 count until ~10mV and 255 happened at 4.99 VDC on my handheld.
Scaling in evoscan was straight forward, but I'm still trying to sort out the scaling in logworks2.0. It seems that simply writing the equation in the protocol.xml file is not enough to get the logging correct? You need to go into the channel configuration in the logger (and dashboard if desired) and set the range to match the range entered in the protocol.xml file? I haven't verified this with a fresh log, but I was able to get a log that was not displaying correctly to display correctly after making this change.
I'm using (x-52)*0.2368 as my scaling in logworks to get gauge pressure in PSI. The -52 offset is the raw bit count I get at atmospheric pressure (84.77 kPa). I have done this because I feel that because the resolution is in 0.2368 PSI increments with the 4bar that the pressure measurements may remain more stable with this scaling. Atmospheric pressure usually sticks within that range, using the raw bit count instead of subtracting a particular atmospheric pressure may provide a more stable boost reading and was easier as all I had to do was input the raw bit count with ignition on, engine off. Something like x*0.2368-(atmospheric pressure) should also work for logging though if that's easier to use or provides more accurate numbers?
EDIT: I also loaded up the MAP test settings used on the JDM 3bar that Mrfred came up with for 94170015. I'm not real sure what these values do, so I have no idea if they will be effective on thsi sensor. I'll give it a shot though and report back. Reading the requirements of the EGR test to happen though, I wouldn't be surprised if my driving style never even lets these tests run.
I'll try and put a few miles on it today to see if I get a CEL using the 3bar MAP test/EGR test settings.
.