Gotta be false knock

[FortifySteve]

Hi Guys,

I am chasing my tail for almost a month on this and I cannot figure out what the deal is or if this KR is real or not, I am going to check plugs tonight to verify I dont have some internal problem.
If you recall early this year I screwed the pooch and had my IFR's scaled totally wrong, this led to a complete retune of the truck. Ive been fine tuning it ever since, Now for some reason as it got way hotter out 100+ it starts spark knocking all over the place, now I did have exhaust hitting at one point (resolved) and I did have an issue where the motor would just touch the engine crossmember (resolved) now I have none of those scenarios present. I still cannot put timing to the motor at all. I have only run 91 from the same stations( 2 local) I always do (high volume station).
I relocated my air cleaner and maf recently but the IAT's are as good as they can be on 106-110 degree days on the highway I see anywhere from 110-135 at times.. it just depends, I also created a ram air port that direct air right into the airbox to minimize my heat ingestion from the engine bay, this seems to have helped.

Now today I thought since I fixed the engine touching the crossmember I would upload my old spark maps, which is reduced quite a bit from stock..
Boy I had some kr.. 10 degrees in a bunch of spots.. I pulled off and removed a bunch.. so much that I lowered it down to 30 at the really low g/cyl and 25 above that and even lower in the cruise areas..
this did help, but I still see some parasitic's present and the truck feels neutered.
the only thing I have not done is put octane booster or race fuel in to confirm the knock. I wasnt sure what everyones position was on that or what brand of booster to use..

[FortifySteve]

timing cut a lot.hplTiming retry 2 .hptpinglikeamofo.hpl

[TCSS07]

Boostane is one I recommend and I'm mobile atm I can check the log tonight

[TCSS07]

Do you hear any engine ticking,knocking or anything ... age/miles on vehicle matters because it might indicate a mechanical issue like pistons,lifters,loose flywheel bolts,etc causing the engine to pick up harmonics. any dtc's?

ive had rust built up between the knock sensors and the engine block to cause issues
boostane claims its safe and it does turn the plugs and o2 orange but ive used it for over 2 years without issue

[FortifySteve]

Ok so I have tried a few things, first off I put E85 in my other tank and ran it that way for a day, while the knock did seem less prevalent I still had 3 degrees in some areas. no where in my spark table has over 25 degrees and in the cruising areas there is 18, I copied the injector data for the motor year over so it is corrected from what I had in there it was 3% off and I didn't realize I had a tune from the year of motor I have (ecu is from a 09 6.2 truck) motor is a 12 5.3 LMG. one thing that did is move the airflow down in the table some which I didn't expect. but the knock is still there, I also made an adjustment for E10 bringing the Stoic value to 14.0 instead of 14.7 which also didn't help.
And this morning I filled up again with 91, I removed even more timing everwhere 2-4 degrees and I still had some knock. I know for 100% am certain this is BS knock, its no longer false its just plain BS, I was rolling down the FWY and watching it randomly knock at only 16 degrees, light throttle around 60kpa... its impossible for it to be knocking as much as the sensors are claiming.

I ordered 2 new sensors today, genuine AC delco, I also ordered some other parts like plugs etc TR6 just to see if there is some other bogus thing happening.. I'm about to desensitize the sensors.. This sucks big time to drive a turd... I literally have in some spots 1/3 of what the stock timing is...

[TCSS07]

yeah i agree, get some new ones in there and recheck

here are torque specs and proper location positions

Attachment 81409

make sure you clean the block surface well - ive had rust and corrosion build up between the sensor and block cause issues

[gottogo]

Have you logged the various types of retard? It might give some clues.

[FortifySteve]

So to answer a few questions, I did check for loose stuff like exhaust other things that might cause it, I checked the plugs for indications of prolonged exposure to detonation and I could see no signs of such.
I am logging all the knock PID's I could find, every cylinder, IAT, TM, etc anything that would give me some sort of indication of where its coming from. The only possible thing I can think of that might be mechanical is a driveline vibration( parts in this order to resolve that) and a trans that makes noise, its whiney.. if that makes sense.
I got another log today with even less timing it has knock all over the place, also its hot as hell here (palm springs area) I do have the IAT table pulling lots of timing for the increased IAT's during the summer, 130 degrees isnt impossible.

Heres my tune right nowE10 cut timing .hpt

[FortifySteve]

dh76shortened.hpl
Here is the log from this afternoon

[lukearmstrong1990]

most of the KR logged is occurs when you're applying load and moderate throttle positions of 38-68 ish %.

all but one KR event I referenced was at points where what I just mention is at MAP values of 68KPA plus but its still in closed loop commanding stoich. your wideband is damn near stoich at those points to.

reduce your lower rpm enable TPS for power enrichment and change the enable MAP to something like 50-60KPA. 75 is too late for PE.

the one KR event I could find that was in open loop with good AFR's was at 87KPA MAP, 4800RPM. at that point your high octane commanded values jump by 5 degrees over 200RPM. (16-21) that's too much of a change in too little time. that's caused the KR. if you want to increase spark by that much do it over 3-5 RPM columns, not 1.

what mods you have?

your idle KPA suggests a factory cam.... with the equivalent of your 93 PUMP gas over here a gen 4 6.0 or 6.2 factory cam with intake and exhaust will only take 16-18 degrees timing. any more makes it ping.

your low octane table is also higher than your high octane. that's a no-no. make it the same for tuning then less than the high octane table for normal operation

[OneMeanZ]

I've never tuned unfortunately but very interested and looking at the logs. What do the O2s dipping before the KR shows up mean? Bank 2 dipped to 462 before the KR read in the log. Is that it actually seeing the knock happen before the sensor detects it?

[FortifySteve]

most of the KR logged is occurs when you're applying load and moderate throttle positions of 38-68 ish %.

all but one KR event I referenced was at points where what I just mention is at MAP values of 68KPA plus but its still in closed loop commanding stoich. your wideband is damn near stoich at those points to.

reduce your lower rpm enable TPS for power enrichment and change the enable MAP to something like 50-60KPA. 75 is too late for PE.

the one KR event I could find that was in open loop with good AFR's was at 87KPA MAP, 4800RPM. at that point your high octane commanded values jump by 5 degrees over 200RPM. (16-21) that's too much of a change in too little time. that's caused the KR. if you want to increase spark by that much do it over 3-5 RPM columns, not 1.

what mods you have?

your idle KPA suggests a factory cam.... with the equivalent of your 93 PUMP gas over here a gen 4 6.0 or 6.2 factory cam with intake and exhaust will only take 16-18 degrees timing. any more makes it ping.

your low octane table is also higher than your high octane. that's a no-no. make it the same for tuning then less than the high octane table for normal operation

Holy crap I completely missed the low octane table!! Wow thank you for checking that out, I have no idea how i missed changing that!!
This is a gen 4 LMG 5.3 totally stock internals, it has shoenfield 1.75 primary long tubes into 3 inch into a y pipe, all mandrel bent, no cats no tight bends, the intake is up in the driver side using a modified 03 truck airbox thats been modified to fit and has a tube from the core support feeding it air so its within 5-10 degrees ambient temps. Above 3200rpm I retard the cam timing some for the top end but its all 0's under that rpm for max torque.

I am running CA 91 pump and now have started e85. Ill post the tune for that.
This is 50-60 kpa running down the FWY, but Ill lower it to see if its is fueling. It would make sense though. Ill smooth the timing out also.
For reference, i run arount 2220 rpm at 70 mph and the drive is from -80ft elevation to my house which is 2800ft, all fwy driving and I usually shift into 4th and stay around 65 ish or the rpm is around 3k at 70.
Basically if you are wondering the drive is 92236-92256 in socal. I start in the mountains in the morning so i have goo IAT's going to work but horrbile IAT's coming home because 119F isnt exactly great air lol.

[FortifySteve]

E10 cut timing .hpt

Here is the tune with the spark correction, Ill play with the PE settings, one thing that makes no sense to me is the factory tune is commanding at cruise rpm roughly double.. locked converter etc on a silverado is no different that this truck.. I should be able to take an oem spark table and at least drive the truck without worrying.. thats why something isnt right IMHO.

[FortifySteve]

Dips in the O2 reading usually indicate a rich condition the lower the voltage the leaner the mixture. I have my wideband on so I know the fuel is pretty close to what its commanding, within reason anyway.
Heres a chart.BaK6Y.png

[TCSS07]

actually high mv reading are rich and low mv reading are lean but during wot you cant rely on those to accurately tell afr

but this last log looks a hell of alot better from previous ones

[FortifySteve]

Whoops Ill fix the post, I dont want to mislead someone.

[TCSS07]

all good - good diagram - in the last log you can see during to wot eq command was .834 and actual was .87/.88 about .5/.6 afr higher than commanded so that little lean spike could of caused the knock blip so try adding a little fuel in that area to help it the actual and commanded get more inline out but also may i suggest lowering the timing a bit - you go from 16 up to 4400 and then to 21 @ 4800 where the knock spiked up which was probably the main culprit - i like to have a smooth blend through the timing transitions

[FortifySteve]

Ok I set the PE to come in based on MAP only, the tps values are 20% which are below what the motor idles at. so purely load based. 60 kpa is the enable value. well see how this works.

[TCSS07]

that should be fine but leave the pe table alone if the eq ratio is what you want and add the fueling in the maf chart and smooth the transition in the timing map from 16 - 21 - you may have to decrease the top end timing from 21 down a little bit but try to have it be like 16-17-18-19 for example

set the pe to whatever afr you want to have and make the maf chart match what you command in the pe ratio table with wideband

[FortifySteve]

Well the EQ ratio closed loop is 1.0 so unless I go in and modify that Ill leave it to PE to add the fuel as needed, right now its set to 1.198 so the commanded should be .834 but I have added some airflow in the maf up top to bring it in closer. The trims are off which I think is because the o2s are in the headers and I have not read how to bring those in. I had the trims at 1% but the wideband is showing it is leaner than the commanded EQ ratio so I am not relying on the O2s at this point.

Also for reference I am pulling 12 degrees of timing for the IAT just incase and at 131F it pulls 9 deg of timing