matt999 Posted July 2 Report Share Posted July 2 Hi, I recently purchased a new Link G4 Knock Light and wired it up the other day. I ran my v8 LS engine and while the light was showing a green light, I tapped on various parts of the engine with a metal wrench with varying intensity. Unfortunately the light never showed red as I attempted to mimic knock. Should it have been triggered to detect knock from that test? Thanks Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 3 Report Share Posted July 3 There is frequency and RPM based filtering in it so its possible a "wrench tap" may not generate enough noise in the expected frequency range, especially at idle. I would try making the engine knock briefly at medium rpm/load to confirm. The knocklink is usually quite effective on an engine like this in my experience, the main thing I have seen affect its reliability is some engines with a "PCM controlled" alternator. The knock link uses alternator ripple as its RPM source to reference the noise profile so that can be lost with some odd alternators that completely "switch off". matt999 1 Quote Link to comment Share on other sites More sharing options...
matt999 Posted July 3 Author Report Share Posted July 3 4 hours ago, Adamw said: There is frequency and RPM based filtering in it so its possible a "wrench tap" may not generate enough noise in the expected frequency range, especially at idle. I would try making the engine knock briefly at medium rpm/load to confirm. The knocklink is usually quite effective on an engine like this in my experience, the main thing I have seen affect its reliability is some engines with a "PCM controlled" alternator. The knock link uses alternator ripple as its RPM source to reference the noise profile so that can be lost with some odd alternators that completely "switch off". Thank you for your reply. I suppose if my alternator does shut off if commanded by my PCM, the Knock light will go to its dim blue or flashing blue stage rather than stay at the green light stage. I will forget about my wrench test and see how the knock light behaves at higher rpm. In case it does help, here is a link to the video where I aggressively tap on the engine. However, it sounds like that won't be enough to artificially simulate knock. The tapping is quite loud though so please view in case it changes the conclusion. https://youtube.com/shorts/iSr5UPgkZic?si=nt8KgvQUao4MELS4 Quote Link to comment Share on other sites More sharing options...
Adamw Posted July 3 Report Share Posted July 3 11 hours ago, matt999 said: I suppose if my alternator does shut off if commanded by my PCM, the Knock light will go to its dim blue or flashing blue stage rather than stay at the green light stage. I have seen either go back to blue, or keep working but regularly report random knock events as it must still see some erratic RPM signal. I have doubts that it would miss the taps you are doing in the video assuming that is somewhere close to the sensor. Is the device powered down when ign is switched off? Quote Link to comment Share on other sites More sharing options...
matt999 Posted July 3 Author Report Share Posted July 3 21 minutes ago, Adamw said: I have seen either go back to blue, or keep working but regularly report random knock events as it must still see some erratic RPM signal. I have doubts that it would miss the taps you are doing in the video assuming that is somewhere close to the sensor. Is the device powered down when ign is switched off? Oh ok I see. The engine is running in the video and yes the light is on an ignition switched circuit. Quote Link to comment Share on other sites More sharing options...
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