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Thread: '94 Corvette Dyno Run Analysis

  1. #31
    LT1 specialist steveo's Avatar
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    thing is.... the knock counts are refreshed many times per second second. if it was in fact a datastream error the knock counts should go right back down. if it was interference on the bus you'd see tons of other data gone bad.

    if the ccm or some other module is in fact injecting garbage despite the fact that you're bus master and they're supposed to stay quiet, the checksum will certainly be incorrect and that event --should-- be rejected but again the knock counts wouldn't stay up like that

    i can (in the next few days) slip you a new beta version of eehack that in theory should reject all those events. although i intended to design eehack to reject anything but a perfect datastream, i seem to remember i found a few bugs concerning rejecting packets with bad lengths or bad checksums.

  2. #32
    Fuel Injected! spfautsch's Avatar
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    steveo - my post was merely aimed at explaining one cause of the extensive error count he's been seeing. Obviously if the knock counter isn't jumping back to what it was in the frame prior to the error that's a sure sign it's not garbage data.

    I just had a thought though, would it be difficult to add the error count from the main window to the log data?

  3. #33
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    Since this thread is active I'll reiterate it here, but I just got a 6-speed '95 and EEHack works flawlessly with it. Zero errors during operation, read operation worked perfectly first try, the whole shebang. Completely different from my automatic '94. There is clearly something different that is causing the operation to be different but I don't know enough to say what that would be. I'll check the FSM to see where my grounds are and make absolutely sure they're all good, but beyond that I'm not sure what to check. Figure I'll toss that in.

    Will be interesting to try that beta version, looking forward to the experiment.

  4. #34
    LT1 specialist steveo's Avatar
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    Quote Originally Posted by spfautsch View Post
    steveo - my post was merely aimed at explaining one cause of the extensive error count he's been seeing. Obviously if the knock counter isn't jumping back to what it was in the frame prior to the error that's a sure sign it's not garbage data.

    I just had a thought though, would it be difficult to add the error count from the main window to the log data?
    yeah would need a new log format, the log was never designed to hold anything but real datastream packets in their entirety. plus that'd be a really weird thing to add to the recorded datastream as the erroneous events aren't recorded so knowing an error happened there would be mostly useless information

    Since this thread is active I'll reiterate it here, but I just got a 6-speed '95 and EEHack works flawlessly with it. Zero errors during operation, read operation worked perfectly first try, the whole shebang. Completely different from my automatic '94. There is clearly something different that is causing the operation to be different but I don't know enough to say what that would be. I'll check the FSM to see where my grounds are and make absolutely sure they're all good, but beyond that I'm not sure what to check. Figure I'll toss that in.

    Will be interesting to try that beta version, looking forward to the experiment.
    well at least we cant' blame the cable if it works on another vehicle...

    i really never tested this on a 'vette, other people did that. the 'silence extra modules' setting is supposed to send the 'be quiet' command to every module we know about. it shouldn't be necessary since without the heartbeat from the bus master the auxiliary modules shouldn't really do anything. i just figured silence every device we know about to be safe..maybe we missed one?

    if we did, we could find it by keeping the bus quiet (just send a shut up packet every few seconds) and run a serial logger until it decides to speak..

    a bad ground is a possibility, ya'd figure those crop up all the time on a vehicle that's mostly non-conductive ??

  5. #35
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    Attached is a log from my '95. In about 40 minutes' worth of driving, the car only had three disconnect/reconnect events, each one pushing the error counter by 8. Absolutely phenomenal.

    The disconnect/reconnect events didn't seem to be associated with anything in particular, so not sure what happened there, but yeah. Figure I'll toss that up.

    Gonna make some changes to the ROM tomorrow and see how that goes.
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