What do you know about Knock sensors?

[Bartly]

So I had my car with a supercharger tuned at a local shop. It was logging the 4 degrees of knock that others have seen with Procharger systems. I asked the tuner to look into it after showing him logs where it went from positive knock to negative when adding race gas. He worked on it for a day and gave it back. He told me he had done several logs and they all show zero knock with the new revision tune. So I hook up my Ngauge and start recording logs, the knock was different in that it was hovering in the -44 to -50 range, which was pretty strange. So I re-installed the gauges on the Ngauge and the knock sensor PID was gone as in it did not exist. So I took the car back to the tuner and asked what he did to the PID. He said absolutely nothing, he stated he didn't turn the sensors off or desensitize them or anything of that nature. So he hooked his laptop up to the car and did some stuff, sorry no clue really what he was doing. After that I was able to find the knock PID on the ngauge. But the problem I have with that is, knock from that point on always read zero and just stays there. I added race gas to see if I could see knock record negative (-) values and add timing like it had done with previous tunes. Nope, just stays at zero through all logs even WOT pulls. I brought the car in with a full tank of gas that I had recorded knock from, and after the tune only recorded zero values. Fast forward to today, I installed an old tune that was recording Knock values other than zero and now it only sees "0" at all rpms including WOT pulls as well. Is there something that can be done to the sensors themselves or to the car outside of the tune that would make them only read as zero? Just wondering what has changed. I hear people talking about summer gas vs winter gas, I only have 91 octane and would think I should still see the knock PID fluctuate instead of just reading zero all the time.
Anyone with any experience on this?

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[Grimace427]

What kind of timing advance were you seeing?

 

[Bartly]

What kind of timing advance were you seeing?

At WOT 18ish with 91 octane.

 

[jgedde]

Maybe he disabled the knock sensor? Not a wise thing to do...

 

[Jn2]

If he set KR advance to all zeroes than the ECM will never add timing(negative values) and as long as the car never gets actual KR it will stay at zero at all times during DD and during WOT bc it no longer has ability to add timing and if you aren't getting KR it also won't show go into a positive value.

 

[Bartly]

If he set KR advance to all zeroes than the ECM will never add timing(negative values) and as long as the car never gets actual KR it will stay at zero at all times during DD and during WOT bc it no longer has ability to add timing and if you aren't getting KR it also won't show go into a positive value.

So, I was wondering if it was something like that, but as far as I know that's done in the tune right? I installed an earlier revision of the tune that I used to see knock events in and now it just reads zero all the time as well.

 

[Bartly]

Maybe he disabled the knock sensor? Not a wise thing to do...

He said he didn't do that and doesn't ever do that. But....

 

[Bartly]

Does anyone know what the Knock PID would read if the knock sensors were unplugged?

 

[Jn2]

Does anyone know what the Knock PID would read if the knock sensors were unplugged?

Pob read zero and throw a CEL for them being unplugged

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