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Thread: Knock Headphone Setups?

  1. #11
    Joe (Moderator) joecar's Avatar
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    If you do splice in, I would use make sure the signal to the PCM is not degraded... i.e. whatever you splice in should have high impedance (this is what the 2 capacitors do in Mitco's circuit) so that the original signal is not pulled down... if you know electronics you might use an op-amp or some low voltage analog buffer.

  2. #12
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    Quote Originally Posted by joecar View Post
    If you do splice in, I would use make sure the signal to the PCM is not degraded... i.e. whatever you splice in should have high impedance (this is what the 2 capacitors do in Mitco's circuit) so that the original signal is not pulled down... if you know electronics you might use an op-amp or some low voltage analog buffer.
    Yeah I would be a little worried about not getting the PCM the signal it needs. I work with a pretty good EE, I'll go through this with him and see what he comes up with.

  3. #13
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    Alright I got a good log. The screenshot below shows the one of the "better" knock retard spikes. It still seems to have a pretty slow decay rate. The peak shown is 4.1 degrees. I multiplied B6207 by 5 in an attempt to make the knock retard decay more quickly. Should I go ahead and make B6207 more like 0.50 or something? It was 0.01 and now around 0.07.

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Name:	Knock Retard 2.jpg 
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    Garrett_GTO_tuned_20161124_1.ctz
    GTO_November_30_2016_2.efi

  4. #14
    Joe (Moderator) joecar's Avatar
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    Try that and take a log, you will see if that is enough or if you need faster decay rate.

  5. #15
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    I changed B6207 to 0.50 across the board, that definitely made a difference. Any knock retard events are fairly narrow spikes and decay very quickly. The screenshot below shows one instance where there were two events back to back.

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    GTO_December_2_2016_1.efi
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  6. #16
    Joe (Moderator) joecar's Avatar
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    Good job.

    If you see rapid successive spikes (sawtooth pattern) then that is real knock.

  7. #17
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    Ahh okay. I haven't had a lot of successive events, but good to know that I'm not seeing false knock. Is it safe to keep the 0.50 decay rate, or are there other steps I should take (I assume drop the spark table in that area of I consistently see knock).

  8. #18
    Joe (Moderator) joecar's Avatar
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    Try 0.25, and post another screenshot.

  9. #19
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    Got it, set B6207 to 0.25 across the board. I had three KR events on the drive in to work, one of them gave me 3.3 degrees and had a couple successive spikes.

    Click image for larger version. 

Name:	Knock Retard 4.jpg 
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  10. #20
    Joe (Moderator) joecar's Avatar
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    Ok, that looks good to me, when there's real knock then the decay rate is just slow enough to take care of the knock, and it's just fast enough to recover quickly.

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