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Thread: Boost queries

  1. #1
    Reverse Gear

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    Boost queries

    My problem is such (ill paint the picture so you can get an idea of what is shi***ng me to no end!) Tests were done at full Wide Open Throttle (in a fully controlled environment):
    1996 A4 Turbo Quattro
    1st gear 900-6900 rpm @ 16psi at WOT (awesome feeling)
    2nd gear - 2700-6900 rpm @ 16/17psi at WOT (gut wrenching)
    3rd gear - 2750-4000 rpm @17/18psi at WOT and then instantaneously everything stops!!

    It seems that the car stops the fuel and ignition to the motor (just like rev limiter) once 3rd gear has hit past 10-12psi and then the music stops, causing major whiplash to my chest from the seat belt because of the sudden back-down in momentum.

    Anyone experienced this before with an earlier B5? All I want is constant boost pressure at 16psi.
    I do have to mention that I have a T-28/03 Garrett/Air Research turbo (reconditioned and blueprinted to spec. from a Volvo Super Tourer here in Australia) and a full 3" mandrel bent exhaust. (I have posted pics of this thing in previous pages).

    I have been told that the MAF flows to a pretty lame 186 g/ps (gramms per second) and was thinking that this could be the cause. If so, would it be more controlled if I was to incorporate larger diameter induction piping with the hot-wire incorporated in order to try and fool the computer into thinking that the intake air is flowing within the MAF's range?

    I have disconnected the N-75 valve (or factory boost regulator) thinking that it was causing the ecu into realising that I wasn't running standard boost pressure, but the car continues to behave the same way.

    I'm totally stuck for ideas here.
    The whole intake to the turbo has been re-routed for maximum cold air, hence, the filter being placed directly behind the cooling ducts in the bumber.

    Oh, and another question I have: When looking at the factory air box, we have the MAF and another device which looks like a miniature heat shield with 2x plugs/connections. What specifically does this do for the car? I'm under the impression that its got something to do with air intake temps. but still would like further clarification.

    Anyone out there with any ideas?

    Cheers

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  3. #2
    Neutral

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    Re: Boost queries

    Was the car running this setup for a while, good at one time? Or is this a new setup and it is having this problem?

    What have you done to the ECU? Stock? - If so, I'd say theres a chance your ECU is like... wtf is this.

  4. #3
    Reverse Gear

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    Re: Boost queries

    With the k03 factory setup with complete factory exhaust system (albeit a nice rear muffler), the car was doing exactly the same thing, just not at the same frequency.

    The ECU is standard and eveything else is pretty much the same way the factory made it.

  5. #4
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    Re: Boost queries

    I'd say it could be ECU related.. but I am no expert, hopefully someone can chime in. Maybe find someone that can custom fit an ECU for your setup. Im sure some of the other members can give you some shops that do that.

  6. #5
    imported_dumpvalve
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    Re: Boost queries

    Limp-mode?

    Surely fitting such a turbo would require a remap to ensure the ECU is set up in respect to the increased boost.

  7. #6
    imported_dumpvalve
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    Re: Boost queries

    That's spot on really. You need to speak to a few tuners and see what they can offer. I'm pretty sure they'll tell you what FezzR has just said.

    One thing which I'm surprised you might have overlooked though, is the fact that as well as adjusting the fuel, timing, boost and ignition parameters to a safe and reliable degree, a custom remap will release loads more torque and power.

    I'd imagine your car is currently producing around 80% of the power it COULD produce with the right map.

    I'm sure it's fast now, but it will be running very lean, and as a result of this will not be a reliable setup. A good remap will A) Ensure all parts are working harmoniously with each other and B) Give you much better power.

    Get it done!

 

 

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