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Is this Knock ?

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Not an easy one I know but, .... the engine is a Nissan VG30DETT with Forged Pistons and Solid Lifters and also has Twin Plate Clutch fitted ( All the noisy stuff ). Attached are some screen shots of my last log showing what looks like knock, thing is, I can't hear any ... is it likely I just have a noisy engine and the Threshold is just set too low, or is it actually knocking?

Attached Files

What is happening if you retard ignition timing, is it still knocking?

I know hardly anything about knock but I think that the ECU is trimming the timing with not much evidence of effect (that I can see).

The frequency of the high amplitude sounds also looks slower than the cylinder ignition pulses but I look forward to hearing from someone experienced in diagnosing knock.

Hi there!

What does you knock audio sound like? In my opinion you should always listen to give you the right feedback from the engine. From what i can see in the screenshot is that cylinder 4 and sometimes cylinder 5 are somewhat chatty. maybe because of the location on the block. On the linkECU you can lower the gain for these cylinders a bit so that the noise for all cylinders is about the same. And from there determine the knock threshold. Test this while listening to the engine with audio coming from a knock sensor. So that you know what you see is confirmed by what you hear.

Kind regards,

Vincent

I am using a Link G4+ Knock Block for audio and cannot pick-up any knock like sounds ... I have yet to have a chance to do another run with timing reduced in those areas.

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