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Thread: Help Logging Knock

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    Help Logging Knock

    I finally got some new readouts from my logger (after a long time of not having it). I'd like some help figuring out the knock that I'm getting.

    Things to consider:
    I have 9:1 pistons. I'm using 91 octane. It is currently 87 degrees outside with a humidity of about 8% (mostly cloudy, feels hotter than 87). Elevation roughly 3000 feet. Also, Peak PSI is only .66 bar (9.5psi). With 9:1 pistons, the Final Compression Ratio is just over 15.0:1 @ 9.5psi. 8:1 piston final compression ratio is just very close to 13.5:1. I also have 75A poly mounts. The fuel system is entirely stock except that the pump is hotwired, nothing has been replaced regarding fuel since I bought the car. I have not tried running the same setup with 100 octane. I'm going to try it when I run out of the 91 that's in my tank. My wideband does not read any extreme conditions when doing test pulls (or ever)

    I don't know if this might cause phantom knock but my carrier bearings are shot and I feel vibration from the drive shaft almost all the time, accelerating and decelerating.

    I'm looking to figure out what might be causing the knock and if the knock is from a legitimate source. Attached is the primary log that I'm working with.

    Datalog_9_23_2010_12_30_9.PDB.xls.zip

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    I Kill Threads verified Feedback Score 1 (100%) Goallie11's Avatar
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    It does look like you are knocking, you can typically tell when theres a knock condition and low timing.

    Any time I've seen my car knock the timing always dips below 20, and yours is doing that too.
    1992 3000GT VR-4
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    What causes that? Did you fix it? What should I look at to fix the issue?

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    rawr. verified Feedback Score 4 (100%) Atrosity's Avatar
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    An Apexi ITC can advance your timing and may solve your problem. IIRC
    vroom vroom i drive a 93 toyota mr2.

    https://car.social

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    I have 92 heads on a 94, I can adjust my timing manually.

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    I Kill Threads verified Feedback Score 1 (100%) Goallie11's Avatar
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    You really have to lower your boost until you can get your timing adjusted. Like Atrosity said an Apexi S-ITC can do that though it's rather old and hard to find, or you can get any other engine management really.

    I have an emanage blue that I have yet to install but it can control timing as well, it's main purpose being fuel control.

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    In this case, with a CAS, would you advance or retard timing?

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    You want to retard the timing to reduce the knock.
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    The low timing you see is the ecu's response to the knock. The ecu sees the knock and retards the timing to stop it. Retarding timing usually reduces power. You may be having a fuel issue. I had low fuel pressure and some knock and my wideband was reading pretty normal.

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    @ RL7, that's what I'm concerned with. I have a large portion of my fuel upgrade but I haven't gotten the rest that I need to complete it. I've suspected for a while that I have a fuel issue but it's completely conjecture at this point, I have no evidence. I do have a replacement stock FPR that I'll probably put on to see if there is any affect after these evenings run of tests.

    I did retard the timing just now but I haven't had the chance to test drive it. At least at idle, without actually putting the car under load, the engine sound a bit smoother. I wont know if there is any change until tonight but I wont really be able to analyize the data until tomorrow at work (I hate how the palm software doesn't work on Windows 7 64)

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