Feedback knock question
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This is a discussion on Feedback knock question within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; Was driving home today and accelerated to pass someone on the freeway at around 70 and seen some feedback knock ...

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    Feedback knock question

    Was driving home today and accelerated to pass someone on the freeway at around 70 and seen some feedback knock on my Aeroforce Intercepter gauge. It never climbed or anything, it just all of a sudden appeared as -1078 and I got out of it. I was in fifth gear around 3000 rpm's if I can remember and slowing depressed the throttle to pass. I don't often drive on the highway so I'm not too familiar with how the car acts under these conditions. I could replicate the -1078 each time I depressed the throttle past 70mph. I did it twice.
    Does anyone have any experience with the Aeroforce gauges? If not, does anyone else's feedback knock do this?
    '09 silver WRX base sedan. Stock-for now...

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    Registered User khaos's Avatar
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    High gear and high load (ie, flooring it in 5th/6th to pass on the highway) tends to produce feedback knock. Everything I've read on the subject says that this is normal under those circumstances.

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    High load at 3000 rpms, already going 75? I thought a high load situation would be flooring it while trying to get it up and going. I was already up and going, and I didn't floor it. I slowly depressed the throttle. I couldn't have been at 50% tps at the time. I'm confused. I high load situation for fifth gear would around 2400 rpms and under wouldn't it?

    I should record this and try it again. I'm just learning some of the functions of this gauge.
    '09 silver WRX base sedan. Stock-for now...

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    Registered User khaos's Avatar
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    Like I said, I was basing my response off of different threads I've read about it.

    Is there any way you can log it? Have you been able to replicate it at all?

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    Yes, it is repeatable. I'm going to the local shop today. Will see about either a tactrix cable, or a log run maybe.
    '09 silver WRX base sedan. Stock-for now...

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by New09wrx
    Yes, it is repeatable. I'm going to the local shop today. Will see about either a tactrix cable, or a log run maybe.
    If you're getting knock in a repeatable load/RPM range, then you may need to think about adjusting your ignition advance tables.
    2005 WRX STi (Mods | Virtual Dyno)

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    I was thinking that... That's jacked up that a factory tune can't keep this car in one piece. How in the HELL would average joe blow know their car is knocking? It's just sheer luck for this car that I'm a car enthusiast, and always monitor **** to see what's happening. I can see why people blow these cars up by just buying them and driving them. It's a shame they're made to blow up from the factory, as they're pretty fun rides otherwise.
    '09 silver WRX base sedan. Stock-for now...

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    Registered User nsibanez's Avatar
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    Quote Originally Posted by New09wrx View Post
    I was thinking that... That's jacked up that a factory tune can't keep this car in one piece. How in the HELL would average joe blow know their car is knocking? It's just sheer luck for this car that I'm a car enthusiast, and always monitor **** to see what's happening. I can see why people blow these cars up by just buying them and driving them. It's a shame they're made to blow up from the factory, as they're pretty fun rides otherwise.
    They don't blow up just by driving them
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    So if I drove this WRX how it was intended to be driven, but with this knock happening all the time, and factory Subaru oil in it like the owner's manual says, you're saying it wouldn't blow up in the near future?
    '09 silver WRX base sedan. Stock-for now...

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    Registered User nsibanez's Avatar
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    The way the car is "supposed" to be driven is just like any other mass produced car on the road
    Stinkeye member 520

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by New09wrx
    So if I drove this WRX how it was intended to be driven, but with this knock happening all the time, and factory Subaru oil in it like the owner's manual says, you're saying it wouldn't blow up in the near future?
    They have to account for numerous fuels, elevations, etc. One size does not, in fact, fit all. They have to calibrate the ECU to account for so many factors including that it gets the performance they're advertising as well as minimizing issues.

    Personally, I wouldn't even wait until motor break-in was complete before recalibrating the ECU, but I would do so knowing that my decision to do so could void any warranty on the car. That said, I'm not the typical owner.
    2005 WRX STi (Mods | Virtual Dyno)

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    What did you do to your ecu when you got yours?
    '09 silver WRX base sedan. Stock-for now...

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by New09wrx
    What did you do to your ecu when you got yours?
    Boost, ignition timing, fueling, AVCS, and DBW tables. Depending on what's defined, possibly some of the OBDII section.
    2005 WRX STi (Mods | Virtual Dyno)

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    "Never trust anything that bleeds for a week and lives ..."

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    Why would you mod so fast? Is it because the stock tune sucks?
    '09 silver WRX base sedan. Stock-for now...

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by New09wrx
    Why would you mod so fast? Is it because the stock tune sucks?
    Because I can. I'm a tinkerer by nature, and would want to optimize the tables to suit my driving conditions. I've liked what I've done with the '09+ EJ WRX for customers, and wouldn't want to deal with what Subaru offers for myself.
    2005 WRX STi (Mods | Virtual Dyno)

    Resident Tuner @ WTF Tuning

    "Never trust anything that bleeds for a week and lives ..."

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