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2JZ Bosch KS4-P Knock Sensors and Threshold

MoTeC M1 Software Tutorial

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Hey all,

I recently have been working on a dyno tune and trying to make sure my knock control is dialed in as well as possible.

I ended up lowering my knock thresholds to better suit the "noise" curve and averages from the cylinders.

Would anyone be will to share what their knock thresholds are for if running a 2jz and the Bosch Wide-Band sensors? I just would like to compare to see if it is reasonable to leave them where they are at or if I'm being too conservative. Currently my thresholds are dependent on RPM but have thought of making the table 3D and referencing RPM and Engine Load Normalized as I've certainly noted more "noise" when running more boost.

I have a fully build motor and am running on e85 so I would rather not leave a lot of timing out if increased values can be ran safely.

Thanks for the help!

Hey Trevor,

If you haven't already you should definitely use a set of knock ears to validate the knock level channels are accurately representing what's happening.

When you're configuring the knock control it's good to set 2 of the frequencies to first order and 2 to second order so you can see which gives a better signal to noise ratio.

The thresholds you configure are relative to the values you're seeing in the knock level cyl channels which are influenced by the gain settings for each cylinder so referencing someone elses setup probably won't be all that relevant.

Thanks for the reply Scott. I have been debating buying a knock box or the like to do what is referenced above. Currently, I am tuning at a hobbiest level and just trying to determine if its worth the investment.

I do have the knock setup with 2 frequency levels as you mentions. I also manipulated the cylinder sensitivities to get the most consistent patterns. Landed on all cylinders at equal sensitivity of 85hz.

Also, hear you on the knock thresholds, just looking for piece of mind due to general inexperience and not wanted to trust my own judgement.

Trevor

Hi Trevor,

For a bore size of 86mm, you should have a knock frequency of 6.7kHz for a first order, and 13.4 kHz for a second order. We use the second order on one of the channels as a filter, if it is actual knock, you should see a matching peak noise with a small attenuation, at the same time in both frequencies.

We usually reply within 12hrs (often sooner)

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