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  1. #1

    code 25 = knock sensor = long ride home

    02 F-12X.
    I've had it for about 7 hours. It's now throwing a code "25" - almost any time past 3000 rpm. We were about 10 miles out when it started doing this.
    It seems to run best at WOT for short bursts, but it was a long ride home.

    So I know that this is an indication of the knock sensor. I've got 93 octane in the tank.

    It seems that the code 25 can occur for a variety of reasons - including a bad knock sensor, bad boost solenoid, or bad wastegate actuator.

    What's the best/ least expensive place to start for diagnosis...

  2. #2
    The WGS tests OK - it's closed when off and pulses (letting air through) when on.
    The WGA seems to work ok, I don't have the best boost gauge... But it clearly opens the wastegate.
    I could have freed something up. The WGS was hanging free, so someone has messed with it before.

    To test WGS failure, couldn't you simply by-pass it, cap the "T" and run straight compressor pressure to the wasteagate?

    Is the function of the WGS to help the turbo spin up faster or actually increase max boost like a boost controller?

  3. #3
    I build Horsepower
    NitroShark's Avatar
    Join Date
    Jan 2006
    To test the wastegate you apply air to it using a regulator. When you get to 7-8 PSI the rod should start to move by 10-12 PSI the rod should have full movement which is about 3/8 of an inch.

    The function of the wastegate is to bleed off air going to the turbine, By doing that it control's the boost by varying the turbine speed.

    Think of it as a large valve in a tire which opens up to let air leak out.


  4. #4
    Nitro - I've done turbo and supercharger implementations on older OHC imports. Full ECU replacement and motors built for boost.

    I've probably read most of your posts in regard to the WGA and WGS. I can find a hand pump and figure out if I'm getting exactly 3/8 on 8psi.

    What I'm reading tells me that the WGS isn't particularly reliable and unless it's failed constantly - which doesn't always happen, it's going to be a replace and pray type deal.

    As such, I'm considering an aftermarket boost controller and adding a gauge. I really hadn't planned on tweeking this ski at all....

    We need to keep a known good WGS around for people to use for testing...

    Nitro - BTW - when the WGA has to be replaced, what are you buying to replace it with?

  5. #5
    Follow up: Replaced KS - we actually started having this problem more and more frequently until I could get it to trigger a "25" on the hose at 3200 RPM.

    Checked continuity between KS and ECU connector.
    Checked continuity between KS and ground.

    Replaced ECU. The 02 F-12X ECU part number is auto-superseded by the ECU for the 03 F-12X (according to my parts diagrams). Cost is over $300 retail. Around $240 wholesale.

    Replaced the ECU, ran great for 2 hours yesterday. I wonder if early ECUs have a high incidence of this failure?
    Last edited by dcg9381; 06-24-2009 at 09:35 AM.

  6. #6
    Bump. Did you find the problem?

  7. #7
    where did u get an ecu? i cant find one anywhere.

  8. #8

    Join Date
    Mar 2012
    Gulf Shores, AL
    I easily found ecu for the aquatrax using Google.....

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