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Distinguishing Knock from Mechanical Noise

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Hi guys, after some advice with how you guys deal with mechanically noisy engines where its hard to hear exactly what is going on?

This is one of those situations I guess where you fall back on your experience, but if you're like me you don't tune cars day-in day-out, you won't necessarily have that!

I use Plex V1. Quite often I hear what I believe must be mechanical noise, which appears around the knock frequency, approx 2/3 rpm range ticking / buzzing and can't be removed by pulling any amount of timing. Switching between 1st & 2nd harmonic doesn't help if the noise is at or around the knock frequency. So this leaves me then with zero confidence and it's frustrating - so do you guys have any tips & tricks for working around this?

I also find it difficult to induce light knock under "safe" conditions with boosted engines with relatively low compression - what I mean is, to generate knock conditions at lower rpm/load to establish a baseline for knock vs noise and to get "tuned in" to the engines own knock sound.

So what do you guys do? Practical real world experience please, not theory :D

Hello i use plug reading and dyno figures to play it safe. i tune several engines a month like this, it used to scare me a lot but after 30 years I've got used to it, often shifting the knock sensor to the head will help also

Hi Ross,

Thanks - I’ve often checked plugs for evidence but always been concerned also that light knock not be immediately obvious and go undetected.

So I guess I can only work on the basis that if pulling timing doesn’t make a noticeable change to the noise then it must be mechanical noise and not knock?