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This is a discussion on Stage 1 Tuning?... seriously. within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; I'm less worries about the boost numbers than I am about the performance outcome. I could care less about bragging ...

  1. #31
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    I'm less worries about the boost numbers than I am about the performance outcome. I could care less about bragging about "my car does xxx, or pulls yyy." For me its all about the feel behind the wheel.



    Got this from another forum. The earlier start and steeper torque curve is what drew my eye towards stage 1. It shows a 65ft/lb increase in torque over the stock tune. Does this seem unrealistic with no other mods? According to the OP everything else on the car was stock and the run was at 16psi so certainly not dangerously high boost. Here's the link to the whole thread on nasioc:

    Dyno Tune: Stock 2011 WRX Stage 1 - NASIOC
    Last edited by crjwingman; 09-13-2013 at 01:59 PM.

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  3. #32
    Moderator Donkey's Avatar
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    Quote Originally Posted by zax View Post
    Matty: Keep in mind that relative pressure is a function of absolute pressure and ambient pressure, and ambient pressure is read by the MAP sensor right before cranking. So if you are going from sea level to 10,000 feet without stopping and shutting the car down... the ambient pressure will be incorrect and relative pressure targets will not be correct.
    If I remeber correctly the USDM WRX's/STI's have what they call a Barometric pressure sensor mounted in the ECU that reads atmospheric pressure. When it goes bad you have to replace the whole ECU as the sensor is not removable or sold as a part. It is constantly active. The older vehicles had it mounted to the passenger strut tower.
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  4. #33
    Registered User frenziedcage's Avatar
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    The stock tune is intended for every environment, proper emissions not to mention very conservative on the stock map. It was designed this way with the intent of making the car last a very long time.

    Why not ask yourself why don't they put all aftermarket parts on a wrx from factory?
    Why don't they put a bigger turbo like a gtr35 why not bigger injectors why not a better flowing dp?


    You can ask yourself these redundant questions but the manufacture builds cars to last they don't build cars with the enthusiast in mind.

  5. #34
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    Quote Originally Posted by Donkey View Post
    If I remeber correctly the USDM WRX's/STI's have what they call a Barometric pressure sensor mounted in the ECU that reads atmospheric pressure. When it goes bad you have to replace the whole ECU as the sensor is not removable or sold as a part. It is constantly active. The older vehicles had it mounted to the passenger strut tower.
    Ron, I actually read something similar on RR forums, but I'm not sure if anyone has been able to prove this statement. As per my understanding there are two theories on ambient pressure: 1. Ambient pressure is read by MAP before cranking (when manifold pressure = ambient pressure) and 2. Ambient pressure is read from a pressure sensor on the ECU board on 2.0L or via a separate sensor on the Air Pump on 2.5L.

    Fantastic if you can further clarify.
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  6. #35
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    Quote Originally Posted by crjwingman View Post
    This is the kind of info I'm looking for. Thanks. Why would the car need a real time measurement of ambient pressure to determine turbo boost? We aren't looking for inches of mercury, just the pounds per square inch. Maybe my physics theory is wrong but it should be able to measure PSI without knowing ambient pressure. If I fill a scuba tank to 2000 psi, it might go up or down as the ambient pressure changes but the gauge is always going to read accurately.
    You're not wrong, but your understanding is not quite correct.

    The MAP can only read absolute pressure in the manifold. Due to the way Turbochargers work, the ECU interested in the pressure ratio across the compressor (I won't get into the details) to remain within the efficiency range of the turbo. For this reason, the ECU also requires RELATIVE pressure. Relative pressure is the pressure difference between the ambient environment and the manifold (this is also often referred to simply as "boost" e.g. "how much boost are you running?"). All boost targets managed by the ECU are with respect to relative pressure. Since the MAP cannot read relative pressure directly, ambient pressure must be known to calculate the relative difference.
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  7. #36
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    Quote Originally Posted by zax View Post
    Ron, I actually read something similar on RR forums, but I'm not sure if anyone has been able to prove this statement. As per my understanding there are two theories on ambient pressure: 1. Ambient pressure is read by MAP before cranking (when manifold pressure = ambient pressure) and 2. Ambient pressure is read from a pressure sensor on the ECU board on 2.0L or via a separate sensor on the Air Pump on 2.5L.

    Fantastic if you can further clarify.
    This is from the FSM for the 2.0L's but is the same for the 04-05 STI's. The later models I guess have it in the secondary airpump solenoid/sensor.

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