Close

    • Cobb Tuning's Mitchell McKee clarifies Porsche 991.2 9A2B6 3.0 MAP sensor and tuning details

      PorscheBoost recently posted an article regarding restrictions in tuning the 9A2B6 3.0 turbo flat-6 platform currently poses. Mitchell Mckee of Cobb Tuning (and his own M-Engineering.us consulting service) helped clear up several details.


      First of all, the MAP sensor is a 3 BAR unit and it is used by he RS3/TT-RS. 3 BAR is obviously 43.5 psi and after you subtract atmospheric pressure of 14.7 psi or 1 BAR you are left with 28.8 psi as to the boost the sensor is capable of reading.

      Quote Originally Posted by Mitchell McKee
      The 991.2 has a 3 bar map sensor on it stock. It is a SENT sensor meaning it is different then traditional map sensors and SENT stands for (Single Edge Nibble Transmission). My guess is that when you log with some generic logger it will only read to 22.5 but that is because it is a mode 1 PID limitation. It is the downfall of not having real dataloggers on cars and simply relying on standard tools.
      It is a different style sensor but traditional loggers will not show you if you are making higher than 22.5 psi. Cobb wrote their own software which is capable of higher level datalogging.

      If you have a tuned 991.2 you will notice that the boost reading of the factory gauges is far off.

      More from Mitch:

      Quote Originally Posted by Mitchell Mckee
      I have attached a datalog showing a 991.2 Turbo running 25.5psi of boost. If you look at boost you will see the 40psi but remember to subtract ambeint pressure from it which at the time was 14.7.

      So this begs the question, are cars boosting higher and traditional loggers just not showing the details? Are certain tuners able to go higher than 22.5 psi of boost?

      We'll hopefully have some info on that shortly but in theory we have established 28 psi should be possible and perhaps there are limitations in the ECU that are preventing higher boost but the factory MAP sensor is capable of reading more than 22.5 psi.

      Thank you to Mitchell McKee ( @magnumpsi ) for his help clearing this issue up.

      This article was originally published in forum thread: Cobb Tuning's Mitchell McKee clarifies Porsche 991.2 9A2B6 3.0 MAP sensor and tuning details started by Sticky View original post
      Comments 7 Comments
      1. F16HTON's Avatar
        F16HTON -
        There is also a boost pressure sensor on the passenger side intake manifold

        Number 14 on this image

        Attachment 57620



        Number 19 on this image

        Attachment 57621
      1. 93siro's Avatar
        93siro -
        So why not install an aftermaket boost gauge to see where things at?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        So why not install an aftermaket boost gauge to see where things at?
        I'm planning to. Not everybody has one.

        Some people are relying on the factory gauge which is way off.
      1. George Smooth's Avatar
        George Smooth -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        I'm planning to. Not everybody has one.

        Some people are relying on the factory gauge which is way off.
        Will be keen to see the difference. On VW for some strange reason the boost gauge shows target boost and not actual.
      1. Xiao's Avatar
        Xiao -
        Im readding upto 1.6bar peak reading at 3rd gear, only got it when the weather is really hot it tends to overboost a little. The command was actually right under 1.45-1.5bar , that's what I usually got, while the dashboard shows only 1.2bar maximum, I assume GTS can show upto 1.3, I'm not sure about the base model.

        I'm using a generic ELM327 obd port, and Scanxl logging tool, bought at www.palmerperformance.com. Very convenient tool. This is where I got all the logs, graphs with the computer.

        For a boost gauge, apart from installing the vaccum source, I still use the same Obd port, and connect to an Android phone (you can use an old one with no sim as a gauge),hang on a bracket on to the windscreen. I used the "torque" app, I used it to monitor boost and most cases the IAT in various conditions.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Xiao Click here to enlarge
        I‘m readding upto 1.6bar peak reading at 3rd gear, only got it when the weather is really hot it tends to overboost a little.
        Interesting. That puts you at roughly 23 psi.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Xiao Click here to enlarge
        I'm using a generic ELM327 obd port, and Scanxl logging tool, bought at www.palmerperformance.com. Very convenient tool. This is where I got all the logs, graphs with the computer.
        That's cool. I might buy this.

        The app is $10 on top for IOS.