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Plex V2 Real world testing

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Hi Andre I purchased the Plex v2 knock detection to practice listen for knock during tuning, however I find whenever I am revving towards high RPM nearing redline there is always crackle and pops. But the log is always showing no fine learn knock or feedback knock

it is confusing me been listening to lot of EJ motors lately they all seem to produce crackle and pop near 6000 RPM section.

I was always wondering if those were real knocks or high RPM nearing redline crackle and pops are normal ?

And also FA20 Turbo engine on the Plex v2 on high RPM is lot of crackle pop too.


What do you mean by crackle and pop? knock? Is this something you can hear in the knock gear or from the exhaust?

If you're using the factory ecu then the knock system in those is quite sensitive and I would imagine if you're getting knock it will log the knock sum.

Funny you say about the 6000rpm area though as the last 3 EJ motors I have tuned in the last week have all had severe knock at this particular point.

If you're new to listening for knock and can take a little while to be able to differentiate between engine noise and knock, particularly in higher rpm when you have a lot mechanical noise from the valve train, pistons etc all happening very fast and quite loud.

The pop noise i hear is only through plex knock headphone, the poping noising i heard in earphone is like computer speaker unpluging and pluging into the pcs multiple times eletrical pop at 6000rpm range and up. Ecu registers no knock and dyno shows smooth power curve so thats whats confusing me how 6000rpm and up engine sounds like.

Most knock video on youtubes i found were fixed rpm light load, so when actually lisenting to rpm rise on plex 2 it sounds totally different and hard to diagnose knock through earphone.

I have had the same situation Jinu and it's typically due to the filter you're using. In particular I find that the 10 kHz high pass filter is incredibly effective in many engines, but occasionally it will result in the popping sound you're describing when knock isn't occurring.

I'd suggest trying different filters and you'll find one that allows you to hear knock when it does occur without the false triggering you're getting currently.

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