Tuning PE, is this false knock?

[weinerschizel]

My build specs are listed at bottom incase they are needed. After a long ordeal I've got a functioning Wideband setup. The factory didn't use PE for the truck (it comes on at 90% TPS). I went ahead and copied PE settings from my 1999 C5 Corvette, and bumped up the EQ Ratio table to be doubly safe. I've gotten most of my runs within 5% (on rich side) of commanded AFR.

What I'm struggling with is knock. A friend said, these trucks have VERY sensitive knock sensor settings. I've very nervous to dial them back and honestly I don't even know how.

Is there a good tutorial on "knock sensitivity"?

I wonder if it actually is false knock as I decided to turn PE on at 30% throttle across the board. I'd originally turned it on at 64%. I beat the crap out of the truck and couldn't' get it to register any knock. That's "12 false knock test..." in folder below.

I raised the AFR slightly and saw a slight bit of knock in "13 increase AFR to 12 under 4800 RPM"

Note when I switched up PE the fueling was all off again, on rich side but was just a quick test so hope to dial back PE / TPS threshold.

I also noticed comparing my spark tables from my Corvette to my truck, there's very little advance in the truck tune. Is it possible to still get knock with such little advance?

My tune and log files are loading to folder linked below:

https://drive.google.com/drive/folde...usp=drive_link

MY BUILD

2001 Z71 Tahoe
P59 PCM with factory truck tune baseline
Stock intake

Custom Cam DUR @ 0.050" 210* / 222 * Lift 0.553 / 0.561 LSA115* 4A
Dual valve springs (matched to cam, forget specs)
1.6:1 Yella Terra ultralight shaft mount full roller rockers
Johnson 2116 LSR lifters w/ Manton pushrods (forget series but thicker walls)

LQ9 Crankcase w/ floating wrist pins
Balanced rotating assembly & matched piston & connecting rod weight w/in 1g

Pure Power 460A alternator w/ big three upgrade to cabling

Factory LQ9 heads 317 castings (polished combustion chambers & Exhaust ports)

Built 4L60E & NP 246 TX case specs too long to list

I think that's about it

My NOTES:

Burst Knock: Burst Knock

Diagnosing Knock https://www.youtube.com/watch?v=cXf3fnrZGwU

[Alvin]

Could you post one log in particular you want us to look at.. This might be a case of just bad knock sensors.

As a seasoned tuner.. for gen 3-4 I rarely.. very rarely touch knock sensitivity.

[weinerschizel]

Thanks, @Alvin in the folder (link in opening post) tunes starting with #11 (worst knock retard) and #12 (tested run w/ more fuel).

I have a modified and professionally tuned C5 Corvette. I cannot recall the tuner's name but he's quite famous in tuning community. Used to work for General motors as and engineer but he left to start a tuning business.

I looked at his tune and he pulled out Burst Knock. Possibly also modified throttle tip in (baseline for corvette is probably different than truck so unsure if is his mod or factory config).

Looking closer at my runs it seems the knock comes when I build pressure very quickly in the cylinders & engine revs up quickly w/ 14.7:1 AFR it tends to pull timing.

Long story short, I don't want false knock to mess up my tune. But I also don't mind all these extra "safety" measures in my calibration. When it's fully tuned, I'd probably turn them back on just to keep on the safe side.

How can I tell if it's false knock?

The tune has very little timing to begin with / it's factory spark maps.

I dumped fuel at it to see if knock retard would go away and it did in tune #12 (10:1 AFR-ish), so make me wonder if it's real.

However, I'm literally dousing the cylinders in fuel, afraid I'll flood them. I backed out some of that fuel to 12:1 AFR (#13) and it's starting to see the knock again. Unfortunately, I forgot to save the #13 log file.

[Alvin]

I'm sorry I do not want to download from a link. I'd post the file here.

[weinerschizel]

Thanks Alvin I hear you on the URL it's my Google drive.

I don't know how how to attach anything here. I think I can in original post if it's one or two files? I have an entire evening of tuning in that folder. It's not lettering me attach with any of the given post buttons / icons anymore. I'm trying to upload using the picture button... no clue.

Attachment 139188
Attachment 139189
Attachment 139190
Attachment 139191

[weinerschizel]

I guess that worked go figure.

[Fast4.7]

Thanks, @Alvin in the folder (link in opening post) tunes starting with #11 (worst knock retard) and #12 (tested run w/ more fuel).

I have a modified and professionally tuned C5 Corvette. I cannot recall the tuner's name but he's quite famous in tuning community. Used to work for General motors as and engineer but he left to start a tuning business.

I looked at his tune and he pulled out Burst Knock. Possibly also modified throttle tip in (baseline for corvette is probably different than truck so unsure if is his mod or factory config).

Looking closer at my runs it seems the knock comes when I build pressure very quickly in the cylinders & engine revs up quickly w/ 14.7:1 AFR it tends to pull timing.

Long story short, I don't want false knock to mess up my tune. But I also don't mind all these extra "safety" measures in my calibration. When it's fully tuned, I'd probably turn them back on just to keep on the safe side.

How can I tell if it's false knock?

The tune has very little timing to begin with / it's factory spark maps.

I dumped fuel at it to see if knock retard would go away and it did in tune #12 (10:1 AFR-ish), so make me wonder if it's real.

However, I'm literally dousing the cylinders in fuel, afraid I'll flood them. I backed out some of that fuel to 12:1 AFR (#13) and it's starting to see the knock again. Unfortunately, I forgot to save the #13 log file.

10:1 is still a safe WOT air/fuel ratio. The factory tune runs that rich when it is in catalytic converter overheat protection mode. Not saying you need to run that rich, but GM adds fuel fairly steadily at sustained WOT. Going to say that if you can make knock retard go away with more fuel, you very likely have too much timing.

[weinerschizel]

Thanks @Fast4.7... is that a blanket statement or did you see my tune file too?

I've been wondering about what you said. I'd think for sure that's timing, however, I'm running a VERY conservative timing map. My baseline is from the 5.3L LM7 truck motor (including spark maps). My build is a 6.0L LQ9 w/ custom valvetrain, cam has 4 degrees of advance, not sure how or if that even factors in to spark timing.

I'm comparing it to my tune C5 Corvette / LS1 which has LOTS more timing, as well as a LQ9 truck motor baseline I found. Both have considerably more timing than the spark map I'm using. There's not much timing in the tune to begin with... IDK

Is this burst knock I'm seeing? How do you tell... it only seems to rear it's head when I blip the throttle quickly and it skips a bunch of cells on the table. Also I see a throttle tip in knock table. I compared that to my C5 tune and they are dramatically different. Burst knock is also disabled in my C5 Tune (a tuner did that for the guy I bought car from).

[edcmat-l1]

IIRC, burst knock shows up as KR in the GEN3s. Easy enough test. Zero it out and see if it goes away.

[weinerschizel]

IIRC, burst knock shows up as KR in the GEN3s. Easy enough test. Zero it out and see if it goes away.

Thanks! Out of curiosity, I've been reading up on Burst Knock. It says Delta cylinder air vrs RPM in the tune. However, over what time base / slope? My setting is 0.020 (grams?) across the board / all RPMs. If I can translate the change in airmass to the log then I can tell if it was likely burst knock. I'm currently assuming it is in certain logs as I jump multiple cells on the spark log table and it starts pulling timing.

This video helped a lot... https://youtu.be/jMaqOKiH2NM?si=VKWN8NCqMMC5Zjok

Also I compared my LM7 baseline to LQ9 baseline and noticed knock sensor level, versus RPM, vrs clyinder is a bit higher on the LQ9 baseline than my tune... especially in areas it pulled timing.

backstory, I blew up my LM7, couldn't find a LQ9 locally so I built one from parts and reused my old LM7 computer.

[edcmat-l1]

You don't have a tune file posted and I'm not clicking links. I don't need to watch any videos.

All the GEN3s are a single row table. Just zero it out.

[weinerschizel]

You don't have a tune file posted and I'm not clicking links. I don't need to watch any videos.

All the GEN3s are a single row table. Just zero it out.

Thanks for details... There's no adverse affects when it's zeroed out?

Tune is posted in #5 above.

[Matt Vardaman]

Thanks for details... There's no adverse affects when it's zeroed out?

Tune is posted in #5 above.

None of those files in post #5 say .hpt, we can't trust outside links. It's very easy to add an attachment to a post like this:11-7-23 2002 Tahoe Speed Density 2bar.22 fuel adjust.hpt
I have removed burst knock without any issue. Mine is turbocharged daily driver on ethanol. Local to me is about 65% in the winter. I didn't have any issues on pump 93 either. You can log burst knock on a p01 by adding the channel, but it shows up as regular knock retard as well.

[weinerschizel]

This is driving me nuts. No matter what I click I cannot figure out how to attach something to the post. This image below are the buttons it gives me.

On post #5 I thought maybe I could upload via the picture button. It loaded but now that I test the attachments it doesn't work.

attach.jpg

[[email protected]]

Click on the the "go advanced" at the bottom right corner of that page and then you can click on add attachments (paperclip)

[edcmat-l1]

Click "go advanced" and then it's this button circled in red.

[weinerschizel]

Thanks! I found the upload button

Log file where pulled timing: 11 log WOT Pulled timing.hpl

Tune to richen fuel / test for false knock: 12 false knock test cmd PE @ 30% TPS.hpt

C5 Corvette Tune: tune file.hpt

Baseline LQ9 tune from Escalade: 2002cadillacEscalade6_0.hpt



I think I have a plan of attack. I've been comparing a handful of tune files. My current is from a 2001 LM7 5.3L Truck motor. However, the engine is essentially a LQ9 6.0L short block w/ aftermarket valve train & cam. I'm comparing the LQ9 baselines to my LM7 and the LM7 has different knock sensor settings. The thresholds seem to be lower (more sensitive) where I had the timing retarded.

I think I'm going to transfer the LQ9 knock sensor settings into my tune. Log burst knock, and pull it out if it's hampering things.

I think that would be a safe course of action?

[weinerschizel]

Okay so I desensitized my knock sensor settings by copying the less sensitive LQ9 settings for starters. Tune attached.

I left burst knock enabled. I noticed it wasn't logging any burst knock. Could that still be affecting knock sensitivity?

I probably need to pull some more sensitivity out because every time it pulls timing it's in a different spot. I assume that's false knock, especially if I hit those cells again and it's not registering knock there?

Prior test runs / logs:

Pulled timing from table Spark Table: No effect
Set high octane table to low octane table: no effect

Current Tune: 05 revert high octain table to default LM7.hpt using scanner I:

Forced AFR to 12:1: No Affect
Forced AFR to 11:1: no affect

Log file for above 05 log.hpl

I think I may have went down a rabbit hole with fuel.

Anybody with a naturally aspirated LQ9 / 6.0 L build... have a baseline I could get an idea off of for knock sensitivity?

Or somebody with Johnson LSR slow leak down or even solid lifters who could give me an idea?

Otherwise my C5 Corvette tune is very much desensitized compared to these factory baselines. I'd assume my C5 would be comparable? Is a LS1 w/ Heads, LS7 cam, & Exhaust.

Corvette Tune: tune file.hpt

Note: Truck is fully rebuilt. No rattles, squeaks etc. New motor mounts, entirely new drivetrain, suspension, etc. etc. etc. Nearly a frame off restoration w/o taking frame off.

[weinerschizel]

None of those files in post #5 say .hpt, we can't trust outside links. It's very easy to add an attachment to a post like this:11-7-23 2002 Tahoe Speed Density 2bar.22 fuel adjust.hpt
I have removed burst knock without any issue. Mine is turbocharged daily driver on ethanol. Local to me is about 65% in the winter. I didn't have any issues on pump 93 either. You can log burst knock on a p01 by adding the channel, but it shows up as regular knock retard as well.

Very helpful. Thanks for sharing your tune file!

[horsepowerguru427]

Enable delta cyl air stock numbers are usually around .16(ish) if i recall right when the number increases it desensitizes the knock sensors more. i believe on my Cammed 5.3 in my yukon i had to move it up to .20 because i kept getting tip in "knock" at mid range throttle, but ive seen people run it up higher to disable BKR.