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By filipesbp
#40852
JHolland wrote:
Mon Feb 10, 2020 11:24 am
You need a fixed reference for angle, the spark angle will vary considerably, the knock window should be fixed.
For that it is necessary to sniff input of the ECU, Adding an MAX9924 IC in parallel to the existent MAX9926 should not give many problems because the MAX has high impedance inputs.

Is there something that I'm not recalling? Ideas?
By filipesbp
#40914
I have been checking the what exists professionally to get an idea how that system works and it seems that Plex Knock Monitor is a very good equipment, but they don't use at least a fixed window which makes it easier to design.

Manual: https://www.plex-tuning.com/instruction ... _V2.0.html

What is the problem if not use a fixed window?
I see only if you don't tune the car on the dyno with too much timing advance the cylinder pressure will skyrocketing because it is too much near the TDC.
By NickZ
#40923
filipesbp wrote:
Wed Feb 12, 2020 6:13 pm
I have been checking the what exists professionally to get an idea how that system works and it seems that Plex Knock Monitor is a very good equipment, but they don't use at least a fixed window which makes it easier to design.

Manual: https://www.plex-tuning.com/instruction ... _V2.0.html

What is the problem if not use a fixed window?
I see only if you don't tune the car on the dyno with too much timing advance the cylinder pressure will skyrocketing because it is too much near the TDC.
the problem with not being in the fixed window is it will be sensing knock all the time, there are lots of noises in the engine, this is why it hard to do and isn't really very efficient. OEM knock sensing is made for that engine only, they spend years developing it as each model of engine has a different frequency.
If you want to tune on a dyno most of them will have ANALOG (headphones) Listening for Knock and is more accurate than the electronic version.
By filipesbp
#40942
I've started the schematics, planing this way:
  • Knock: TIP8101
  • External Supply: LM2940CT-5.0
  • Visual Output: LED's bar and a medium current output(light)
  • RPM input: opamp protected
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