alky pressure xfi logging ?

kidglok

Balls Deep
Joined
Oct 10, 2010
razor,

i set up the logging kit with the gauge, my settings are as follows: gain- 36.75 offset -18.375
based on the xfi manual for a .5-4.5 volt sensor these should be accurate(0psi=.5 volts and 147psi=4.5 volts). problem is at key on the sensor is reading .33 volts hence showing me -6 for alky psi at idle. Is this something to be concerned about? i understand im just looking for a trend of pressure throughout the boost curve but i would like to have the pressure as accurate as possible. Thanks
 
razor,

i set up the logging kit with the gauge, my settings are as follows: gain- 36.75 offset -18.375
based on the xfi manual for a .5-4.5 volt sensor these should be accurate(0psi=.5 volts and 147psi=4.5 volts). problem is at key on the sensor is reading .33 volts hence showing me -6 for alky psi at idle. Is this something to be concerned about? i understand im just looking for a trend of pressure throughout the boost curve but i would like to have the pressure as accurate as possible. Thanks
Then set the base at .33 not .5. Every sensor has some drift, altitude, ambient temps, etc. So if your calculations are based on .33 for a zero PSI, then you'll be at zero.

In the end, the reason for a transducer is to watch for trends that change. So once you have your zero rescaled, at that point you watch how much PSI you have at lets say 20 PSI. For argueements sake its 90 psi pressure. Then from now on your looking for 90 psi pressure at 20 psi boost and any degredation of the system will be caught that way. So if you start adding fuel 5% at 20 psi, and your pressure readings are now 80 psi.. the system pressure has changed. Or if your adding fuel and the pressure is still 90 psi, then your fuel system has changed.

Its not important as to exactly what pressure as your car is different from everyone elses car. Now if you want to see if the transducer is tracking correctly, you will read boost pressure on it up until the alcohol system kicks on. So at 6 psi boost you should see 6 psi on the transducer. Thats if your alcohol kit activates at 7 psi. Once it goes past 7, then the pump starts cranking out.
 
Then set the base at .33 not .5. Every sensor has some drift, altitude, ambient temps, etc. So if your calculations are based on .33 for a zero PSI, then you'll be at zero.

In the end, the reason for a transducer is to watch for trends that change. So once you have your zero rescaled, at that point you watch how much PSI you have at lets say 20 PSI. For argueements sake its 90 psi pressure. Then from now on your looking for 90 psi pressure at 20 psi boost and any degredation of the system will be caught that way. So if you start adding fuel 5% at 20 psi, and your pressure readings are now 80 psi.. the system pressure has changed. Or if your adding fuel and the pressure is still 90 psi, then your fuel system has changed.

Its not important as to exactly what pressure as your car is different from everyone elses car. Now if you want to see if the transducer is tracking correctly, you will read boost pressure on it up until the alcohol system kicks on. So at 6 psi boost you should see 6 psi on the transducer. Thats if your alcohol kit activates at 7 psi. Once it goes past 7, then the pump starts cranking out.

exactly what i was thinking. thanks julio
 
Now if you want to see if the transducer is tracking correctly, you will read boost pressure on it up until the alcohol system kicks on. So at 6 psi boost you should see 6 psi on the transducer. Thats if your alcohol kit activates at 7 psi. Once it goes past 7, then the pump starts cranking out.

so based on that this log should be accurate:

alky log.png
 
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