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Thread: 3bar MAP Sensor PID not available? MAP reading maxes out at 105kpa w/ 3bar sensor

  1. #1
    Tuner in Training
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    3bar MAP Sensor PID not available? MAP reading maxes out at 105kpa w/ 3bar sensor

    I have a gen3 4.8 with p59 ecm, just installed a turbo and 3bar MAP from efisource and did the 3bar custom OS upgrade. After getting the car driving and then ready to get into boost for the first time, I noticed in the log that the MAP sensor would max out at a reading of 105kpa for any duration that I was in boost (I probably only went up to 1 or 2 psi actual). I realized I probably forgot to upgrade the pid, so this morning I found these old instructions:

    18. (This step for 2bar and 3bar enhancement only) Open VCM Scanner and connect to the vehicle. Open the Table display (Scan -> Table Display). Right-click the "Manifold Air Pressure (SAE)" PID and select "Delete". This removes the existing 1 bar PID from the table, if you don't do this the histogram will not function correctly.
    19. (This step for 1/2/3 bar Speed Density enhancements only) Right-click the "Mass Air Flow(SAE)" PID and select "Delete". This removes the existing MAF PID, if you don't do this the histogram will not function correctly.
    20. (This step for 2bar and 3bar enhancement only) Right-click again on the table display cell and select "Insert", go to the Engine -> Airflow section and choose either the "Manifold Air Pressure - 2 bar" or "Manifold Air Pressure - 3 bar" PID, double-click to insert it into the table.
    21. (This step for 2bar and 3bar enhancement only) Save the new scanner configuration using File -> Save Config.
    22. You are now ready to tune using your new enhanced PCM.

    But this seems to be for a much older version of VCM Scanner as I cannot even find anything called a 'Table Display' let alone an option for a 3bar MAP sensor when I try to add a channel, only the Intake Manifold Absolute Pressure SAE pid. If anyone could instruct me on how to get the 3bar map channel or whatever it is that I need to do to get the 3bar sensor to actually get read by VCM scanner as a 3bar instead of a 1bar I'd greatly appreciate it.

    I'm having trouble attaching the log file but I'll be working on that after this is posted

  2. #2
    Tuning Addict 5FDP's Avatar
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    You should be able to connect to the computer and then click re-poll for supported parameters under the vehicle tab. Than click add a channel and type in MAP, it should pop up the 1, 2 and 3 bar channels.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Tuner in Training
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    Quote Originally Posted by 5FDP View Post
    You should be able to connect to the computer and then click re-poll for supported parameters under the vehicle tab. Than click add a channel and type in MAP, it should pop up the 1, 2 and 3 bar channels.
    I have re-polled for supported parameters and the weird thing is that I can actually see "Manifold Absolute Pressure - 3bar" for a split second while its running through all of them, but then after I do that there is still no channel option for a 3bar MAP

  4. #4
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    Quote Originally Posted by 5FDP View Post
    You should be able to connect to the computer and then click re-poll for supported parameters under the vehicle tab. Than click add a channel and type in MAP, it should pop up the 1, 2 and 3 bar channels.
    Nevermind I did it again with the key on and that did the trick! Thanks so much man, I'm gonna go try this out and hopefully log some boost!

  5. #5
    Tuner in Training
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    Quote Originally Posted by 5FDP View Post
    You should be able to connect to the computer and then click re-poll for supported parameters under the vehicle tab. Than click add a channel and type in MAP, it should pop up the 1, 2 and 3 bar channels.
    Just to follow up, I've now measured 5psi of boost so it did indeed work! Thanks again for the help