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  • DPF Pressure

    For those using Torque I'm sure you know that it has a built in PID for DPF Pressure. Also, I'm sure you've noticed that the number is, well, way off. If you create a custom PID and use the formula "[7A]-32768" (without the quotes) you'll get a much nicer number. It's nice and low when idling and it will jump up significantly when on the go fast pedal. I'm not sure if the number if correct but the geek in me tells me that the raw number needs adjustment and 32768 was just too much of a coincidence.
    Last edited by dandin; 04-01-2018, 06:49 PM. Reason: Facebook link not public

  • #2
    Thanks for posting and yes I have noticed that the Torque pro built in DPF pressure sensor doesn't make sense. I think mine reads 2260 bar at tickover and just over 3000 bar when driving.
    Unfortunately I get the message "sorry this content isn't available at the moment" after clicking on your link so I have been unable to see what you did.
    Did you edit the existing built in pressure pid or delete it and create a new one?

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    • #3
      Looks like the link isn't public. I'll upload a copy locally or a picture of the custom PID from torque.

      You made me realise that not everyone might be using psi to measure pressure. Seems you're using bar. That said, I think you can still use the same formula. If not, you'll just have to convert 32768psi to bar (just divide by 14.7)
      Last edited by dandin; 04-01-2018, 06:52 PM.

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      • #4
        Nice one Dandinđź‘Ť
        That data is the electronic conversion of the raw analog voltage signal I was pulling out of the middle wire in the DPF pressure sensor.
        It sat at .8v at idle and peaked at 1.5v full noise. In saying this I have seen idle voltage peak at 1.1v and full noise peak at 2v before a regen was due.
        i like how it shows exhaust velocity having an impact on pressure sensor.
        out of curiosity do you think the number of 32768 is in pascals? That would put the Number to just under 5psi.

        Would be great if you could put up some converted pressure readings you are getting now so I can have a reference to the analog voltage output.

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        • #5
          Tried the [7A-32768] PID formula and didn't work, tried [7A]-32768 and it came to life. At idle it fluctuates between -8 and 5 PSI, at 2000rpm it goes up to about 25PSI. Is the figure displayed differential press across the DPF ?

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          • Spook1205
            Spook1205 commented
            Editing a comment
            It is mate
            Although they don’t seem correct.
            Shouldn’t have -8 psi and 25psi of back pressure is cranking high.
            I have a printout from a Toyota scan tool on a failed regen from a faulty cat which had an rpm of 1200 and PDF pressure difference was 55kpa or about 8psi
            Last edited by Spook1205; 05-01-2018, 11:51 AM.

        • #6
          Looking forward to dandin posting the custom pid. It is a long time since I played around with this on torque pro but seem to remember there is a default DPF pressure built in which is the one I quoted reading in bar. I may be wrong but I do not think that default pids are editable? I have tried another extra pid without much success which was for differential pressure, this suggests a pressure difference between each side of the filter.

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          • Spook1205
            Spook1205 commented
            Editing a comment
            In the heavy vehicle industry all MID and PIDs are standard across manufacturers unfortunately for the light vehicle industry manufacturers still use their own protocols and may not cross reference with other manufacturers. Fortunately the government forced that all protocols can be interpreted by a standard On Board Diagnostic program (OBD2).

        • #7
          Went for a drive yesterday and using the DPF diff press equation [7A]-32768 ,it ranged between 100 and 200. Would that be in kPa or PSI ?
          If it's in PSI, do I have a clagged DPF ?

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          • Spook1205
            Spook1205 commented
            Editing a comment
            Definitely not PSI that would be 3 to 6 times the pressure you put in your tyre.
            What I like about reading the sensor value in its analog form is its true data. Once you know what voltage comes out of the DPF pressure sensor it’s easy to test and evaluate.
            Idle .8 v
            High load /rpm 1.5v and will max out at 2v when filter is ready for a regen.
            A blocked DPF voltage will rise quickly to over 2v if you just rev it out sitting there.
            It’s middle wire DPF sensor, use a high impedance multimeter (not a $10 Bunnings one)
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