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Thread: Stock Wastegate boost pressure and bleed valves.

  1. #1
    Periphery is offline New Member
    Join Date
    Jan 2018

    Default Stock Wastegate boost pressure and bleed valves.

    Hey guys,

    Have done some reading over the last few days regarding Boost pressures and have resorted to creating post. (apologies if this has been discussed and you guys know a link that I couldn't find.)

    Firstly, I have had some issues regarding boost inconsistency in my 3 MPS
    3" Turbo back Exhaust
    XEDE piggyback ECU
    Custom Tune.

    all done by the first owner (i'm the 3rd)

    Having some issue with hesitation and misfiring at high load/revs/boost (20psi) and want to reduce the boost until I can get someone to tune it.

    I'm in discussions with ChipTorque (who fitted and tuned) to get it baselined again and a re-tune but it will be a few weeks before I can get it to them on the Gold Coast.

    My Question is, What is the Stock boost pressure of the wastegate? I know the stock boost is 15psi (thanks to this forums previous posts) but what about at the gate?

    Second, and recommendations on manually boost taping? as my current "tune" has boost on Avg at 18psi

    Can I manually bleed it to a safe say 12psi without both the factory ECU and piggyback chucking a wobbly? or even just run the stock wastegate pressure?

    If so on any of the above whats "Best Practice" when adding a manual bleed? ie: off the front of the gate inline into the turbo inlet? or from the back wastegate port inline to the compressor housing and then do you leave the factory boost controlled connected to anything or just blanked off?

    better yet is there already a post on how to do this?

    sorry wall text post, have a lot on my mind and need a starting point and all these questions keep rattling my brain


  2. #2
    Nexus's Avatar
    Nexus is offline Administrator
    Join Date
    Nov 2008
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    Hi, my understanding is that you can run the wastegate at spring pressure as a way of limiting boost. I'm not sure how the XEDE would handle that, but the scenario where you might want to do that is - as an example - I've fitted an alternative turbo and I'm concerned about it overboosting in response to the tune's wastegate duty cycle. I want to run the stock tune and avoid overboost conditions that the alternative turbo might create. This idea was fleshed out as a thought experiment only while planning an ATP GTX2867 turbo swap.

    The two solutions are to (1) bypass the boost control solenoid altogether by rerouting hose or (2) electrically switch the boost control solenoid permanently into the spring pressure state. A dash switch that switches the wastegate between spring pressure and ECU command pressure.

    The electronic solution has not been tested to my knowledge, and I'm not confident enough in mechanical detail to give instructions, but rerouting hose to limit boost has been used successfully as a temporary measure.

    I intend to test the electronic solution when I get around to aforementioned turbo swap.
    "Blue Meanie" 2007 Aurora Blue MPS 3 - 18x8.5+44 SSR GTX01 - 235/40R18 Federal RS-RR - 3.5" ETS TMIC - CPE stg 2 mount - HKS/CPE BPV - 2XS inlet - 2XS short shift - 2XS turbo manifold - Hypertech tune - Leather/Aluminium handbrake - Momo shifty knob - 7" touchscreen - JDM Mazda Retractable dashtop screen assembly - PC based GPS and instrumentation - 36AH reserve battery and C-TEK isolator - TEIN Street Advanced coilovers 1" drop - Superpro bushings - 220Kw/410Nm.

    "Lipstick" 2013 Velocity Red MPS 3 - 18x7.5+48 Enkei RPF1 -225/40R18 Federal RS-RR - CPE TMIC - COBB inlet - CPE stg 2 mount - COBB Stage 1 98 octane tune - COBB shifty knob - 2XS short shift.

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