Knock Retard

[shakenfake]

Okay guys I am having some trouble here that may or may not be my tune I am unsure at the moment. I will give you a rundown of what has happened and what is happening.

1999 Silverado with an LQ4, 862 heads 212/218 low lift camshaft running on 93 Octane tuned by mailordertuner sometime in October 2019.

So it all started with a P0327 code in May 2021 I think. Just figured it was a faulty sensor I would replace it and move on with my life. I have some of the logs from back then as well.
I tried going through all the tests just to make sure that yes this was false knock and that replacing the sensor was necessary, octane booster and electrical testing.
I finally got around to replacing the sensor yesterday and low and behold the P0327 code has gone away! And then was promptly replaced by a P0332 code and a constant 8 degrees of knock at .55-.6 grams of cylinder airmass.

So now I am stuck, I do not believe it to be the sensor as this one was working fine before I replaced the other one and now it is not. I was told by my tuner back in May that I should step up to a colder plug, currently running the TR5IX and was told to get a TR6, I do not believe that will fix the issue but I am willing to try as it is only a $20 investment. I've gone ahead and attached the log for you to see. I have done some more runs after that log but sadly do not have the file for those (fat fingers!)

Any thoughts or ideas would be great. I am installing some headers on Sunday and will install my wideband gauge next weekend most likely. This way I can get some AFR readings as I believe that will be helpful in this situation.7-24-2021 I give up.hpl

[blindsquirrel]

So you had a code for one sensor, replaced it, and now you have the same code but for the other sensor? What do the two sensors have in common? What is the one thing that could affect them both? Do you have diagnostics and wiring diagrams?

[shakenfake]

1. Correct
2. Wiring harness is what I would respond to that
3. I am guessing the answer to this would be bad wiring harness but I am unsure of how to respond
4. Diagnostics specifically being? I have wiring diagrams for that or can get them yes.


BUT I believe I made a break through in this. I set P0325, P0327, and P0332 to no error reported and took the truck out for a drive. I had none of the knock issues I was having previously. I was doing some searching last night and realized that Duh I'm going to get max knock because the code has already been triggered, the truck is trying to save itself.

Now this should not have solved my issue with the knock in other places but it seemed to have. I previously was getting anywhere from .5-3 degrees in the 1800-3200 RPM range just randomly spiking. I have been on one drive with the new tune in place and it seems to have worked. I now do not have any knock above .5, currently I have some at 3600 RPMs at .3 but I think that just needs some timing pulled.

I've attached the new log and my current tune, take a look at it and let me know what you think. I'll take the truck out one more time tonight and see what happens but I believe this may have fixed it.Fixed 7-25-2021.hplKnock Sensor Codes Turned Off 7-25-2021.hpt

[blindsquirrel]

Yes, if you turn off the knock sensors you will no longer get knock detection or knock retard. I don't think that's really a proper fix for a sensor tripping a DTC though. I'd follow the diagnostic steps for the knock sensor code(s) and find out what's causing it.

The wiring is really simple and it should not be a major mystery to figure it out, you already know that futzing with the harness while changing the one sensor caused the other sensor to set a code. This is a solvable problem with basic diagnostics.

[shakenfake]

I didn't turn off the sensors though. As you can see they still work and KR is showing up? I mean sure I can turn off the sensors completely but those codes that I turned to no error reported do not turn the sensors off.

The wiring is simple but I have already run the test to see if the harness is good and it tested good. I do have the diagnostics actually for this I found it. I tested the harness before I replaced anything and everything was all good. I can test it again but I have a feeling it is just going to test out properly, I did not even touch that part of the harness since each knock sensor has it's own channel for the lack of a better word, touching one side won't have adverse effects on the other.

[shakenfake]

Alright double update. Last night I had my girlfriend hold the laptop as I did some pulls and drove around. Where I live the highways are trash and the roads are trash so I end up hitting bumps and shit all the time. Point being that I hit a big bump last night and instant spike to 5.4 which tells me that it isn't an electronic thing, tune, none of that but just something banging around in my engine bay. I am assuming it is motor mounts but I have no idea and don't want to purchase any of those lol so I will probably just leave it since I have all the codes turned off or just turn the sensors off completely.

[kevin87turbot]

As you found out, the P01 computers will still monitor knock and have full knock retard functions, even with the codes changed to No Error Reported. It will just prevent it from going into "full retard mode." (that didn't sound PC.)

It does sound as if you have a mechanical problem.

[shakenfake]

Yeah it has something to do with my motor mounts I believe. Also yes I knew the P01 computers still monitor knock with the codes turned off haha I just was tired of the CEL.

I don't really want new motor mounts though so just gonna leave them for now. Lazy I guess