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Looking at just the knock sensor tells me nothing.
What you're seeing is engine noise. The engine gets louder the higher you rev it. The engine gets louder the more air you push thru it.
If you're seeing 5V all the time, there's an issue as it should be quiet at idle and louder at redline WOT. If you're maxing the sensor at 5V then you're making some serious power! Like 700+hp! ....or you're really hurting your engine....
Basically.... I don't think the issue is your knock sensor.
Hey Greg,
Cheers for the reply.
I replaced the knock sensor anyway as the old one had cracks in and the lead was fraying wiring at its connection to the sensor itself.
It was cheap enough to swap over and just put my mind at ease.
New sensor shows a better signal but like you say is still low voltage as engine noise.
Still getting knock counts to 9 counts at 3000-3500rpm and over and it pulls timing to 5 degrees and CEL.
I don't really think its real knock but aside from using knock ears or a knock box im not sure how I can tell.
I have a tuner here in Sydney Australia who is pretty good with Mitsubishi EVOs and VR4 Galants and Legnums who I have asked to help.
I can only do so much with my limited knowledge. Thanks
Your knock voltage will be close to zero when you're idling, but it should come up when you're on the throttle. Looking at one of my logs I saw knock voltage up to around 1.5 volts during a 3rd gear pull. Yours may not be that high as my car makes 600whp, but if it's staying at less than .1 volts I think you may have a wiring issue or potentially a problem in the ECU. Make sure you log a decent range of throttle positions and rpms though. My hunch is you have a short or a bad ground in the wiring for the sensor. Have you tried cleaning the connection between the knock sensor and the wiring harness up by the throttle body? I think that connection is where my problems stemmed from when I had the same symptoms.
Greg, do you think issues like these, since they seem to be cropping up fairly common, could be related to the hullabaloo about the knock sensor circuits being different between the legitimate VR4 ECUs and the SL ECUs or potentially the clone ECUs? I know you generally think it's not knock sensor related, but in my experience that's the only solution I could come up with. You're much more knowledgeable about the intricacies of the ECUs and code though, which is why I'm curious about your experience.
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Purely anecdotal story, but I've been trying to sort a 'knock' issue as well.
I have a '92 TT, 13Cs, DP, LCDBC, 98 SL ECU/flash - very basic setup.
Prior to switching ECUs, my rebuilt-by-Seth TT ECU would show knock under low RPM low-/no-load conditions; particularly while shifting - usually 3-8 counts, but occasionally maxing out at 28.
I figured this for an anomaly, considering the conditions in which it would occur - it literally would not knock under load or during a pull.
I figured when I had the opportunity I'd replace the sensor and poke around.
In the meantime, I've gone Chrome, w/99 ROM, and the car runs better than ever, but it seems to run a bit richer (not over-rich); when I coast downhill, etc., the old exhaust 'crackle' is gone, and I can't make the damn thing knock - where the LCDBC would report knock previously, it no longer does.
I'm at a loss to explain this; I'd have some logs to post, but as luck would have it, my China knock-off Tactrix took a shit, and any further info will come in the spring (car is parked for winter), when I install RC550s, a Supra pump and Innovate WBO2.
I will have replaced the Tactrix as well - have to flash for the injectors - and will commence logging, hoping to get to the bottom of things.
I'll replace the knock sensor at that time, too.
I would start by swapping the into a different car. If the problem follows the ecu, then you know the cause.