|
Title: Logging Calculation Help (Fuel Pressure Sensor via DS rear O2 sensor) Post by: vavjettaw36 on October 19, 2016, 12:04:36 PM Currently I have a wideband that is occupying the passenger side rear O2 so that I can log with ME7Logger. What I am trying to figure out is my ECU entry for logging Fuel pressure through the ecu like the WB.
The fuel pressure sensor is a 0-5v (0-150psi) Linear, however, the specs are as follows: .5v = 0psi 4.5v = 150psi I am still trying to get a handle on the offset/etc. Since 0 psi is .5v and not 0v like a wideband, I dont understand how to come up with the offset and factor. Thanks, Shawn Title: Re: Logging Calculation Help (Fuel Pressure Sensor via DS rear O2 sensor) Post by: nyet on October 19, 2016, 12:11:01 PM What makes you think you can log these values from the ECU? How does it know them?
Title: Re: Logging Calculation Help (Fuel Pressure Sensor via DS rear O2 sensor) Post by: vavjettaw36 on October 19, 2016, 04:49:55 PM What makes you think you can log these values from the ECU? How does it know them? Because the wideband is hooked up in the same manner. The wideband signal wire runs through wire 4 of the PS rear O2 sensor to the ECU. The ECU can see the voltage of the fuel pressure sensor, I just need the ECU entry so I can log them with ME7Logger. For example, Here is the appropriate entry for your a wideband that where ranges are 7.35 AFR = 0v and 22.35 = 5v: wbafr, {wideband afr} , 0x381116, 2, 0x0000, {WBAFR}, 0, 0, 0.014688064, -7.35, {wideband air fuel radio} So its going to be similar but I have no clue how to offset it since the range is .5v to 4.5v. I need the masterminds that understand the conversions to chime in. Title: Re: Logging Calculation Help (Fuel Pressure Sensor via DS rear O2 sensor) Post by: vavjettaw36 on October 19, 2016, 05:09:39 PM Also found 0x381114 is the correct memory address to use. so far my entry is:
Code: FPRESSURE, {Fuel Pressure} , 0x381114, 2, 0x0000, {WBAFR} , 0, 0, ?, ?, {logging Fuel Pressure}Need someone to help fill in the question marks :) Edit: I think I have figured it out. I started by figuring out the value at 0v and 5v (which the sensor cannot give since it is .5 to 4.5, but it is linear 0-5 so that is fine). So I threw it into excel since its just fast to plug in and drag, and got the bucket for each PSI (in .5 increments), which is: Code: 0 -18.75 So then I could find out my factor: Code: 168.75-(-18.75)=187.5 and our offset is just simply 18.75 (we will make it positive because the ECU will turn it negative. So the final entry should be: Code: FPRESSURE, {Fuel Pressure} , 0x381114, 2, 0x0000, {WBAFR} , 0, 0, 0.1831125, 18.75, {logging Fuel Pressure}Does this look right? I think i got it I will test it tomorrow. |