Help with Knock retard 6.2 L92

[LanceD]

2007 Escalade, slightly tuned (go easy on me, it's my first time) running 87 pump gas and zero mods to the engine aside from removing the cats. On the VCM scanner I am seeing a lot of part throttle knock retard and am looking for advice. I followed the instructions on the tuningschool video about fixing knock but it seemed to get worse after doing that. Also zeroed out the burst knock table (12765) I can hear what sounds like a wrench tapping on the exhaust manifold when it is showing knock. Is it just knocking and I should run better gas? I did change the driver side engine mount too. What confuses me is that it only does it part throttle and very little at WOT. Also there was almost no KR until it got up to operating temps. Here are my scans and tunes for you to pick apart:


Tune2+catdelete is before messing with the spark tables following the tuningschool video
Tune2+catdelete+KR is after messing with the tables
Drive2nocats is a log from after removing the cats
KR1 is a log after messing with the tables.
KR2 is another drive right after KR1

Tune 2+Cat delete.hpt
Tune 2+Cat+KR mod.hpt
Drive2nocats.hpl
kr1.hpl
kr2.hpl

[5FDP]

87 octane is terrible for reducing knock in a 6.2. I thought GM said premium was best for those engines and at a minimum you should run mid grade 89 octane. Part throttle knock was the norm when I ran 87 octane even in my 5.3 truck

You're also asking for a very very lean mixture under power enrichment. 13.35 is way to lean on a truck engine that is factory and I often saw knock when computer was requesting that ratio. That fuel ratio on 87 octane even with mild timing won't work well together.

I suggest running around 12.2 to 12.5 for best performance and reliability. Lean is mean but not when you want the engine to survive for a long time. You're losing power at full throttle because you have the timing so low (down around 10-13 degrres) and the mixture so lean. A richer mixture with more timing will make more torque. Low 12's air fuel with low 20's on the timing is far better.

If the knock sensor function is like I remember the computer doesn't really "turn on" the sensors until the certain operating temp is reached. Worthwhile to check motor mounts too. Being such an old truck those motor mounts are likely to be smashed if original.

[MeshaalMMT]

better gas!

[lukearmstrong1990]

running a half point richer in AFR can help an engine prone to KR from low octane fuel be more stable. also reduce timing. especially where its transitioning into the load and airmass isn't stable.

[LanceD]

Made a few changes to it, let me know what you think, I'm about to go squirt it and give it a try.

Tune3=mild.hpt

[5FDP]

Both timing curve should not have the same numbers, lower the low octane table as it needs to have less timing in it.

If you reference the stock tables, one is always higher than the other.

[LanceD]

yea that wasn't a good tune, it wouldn't even start. I went back a few tunes and it's knocking the same amount, went to the gas station because it's almost empty and filled up with 91. Here's the scan from after the 91. The knocking sounds like tapping on the exhaust and does it at most rpms but only under load. Shouldn't the noise go away if it's actual knocking with 91? I did recently replace the drivers side engine mount.

nocats+pe91oct.hpl

[5FDP]

Honestly I think you should try reverting back to bone stock timing for both high and low tables and see what it's like. Start back at square one with good fuel, even return the knock decay table back to stock.

[LanceD]

I will do that and report back.

[LanceD]

Went back to stock for the most part, left the PE stuff in there and it seems a lot better, at least I can't hear it knocking any more.

back2stockish.hpl

[johnny_boii]

You should get someone to tune it for you so you can see what they changed and then read some more forums on here to try and get a grip on what changes need to be made and what should be left alone. How are you tuning for WOT with no wideband?

[Jmandernach]

The L9H 6.2 in my Sierra Denali will knock all day under load on 87 with the factory tune, I believe the L92 and L9H engines are basically the same. Yes it sounds like tapping in the exhaust. Even on 93 I'm not able to add much timing to the curse sections, without significant knock. It will take a few degrees at WOT on the 93.

As johnny_boii said get yourself a wideband before you do any more WOT tuning.

I find these truck benefit a lot from a good trans tune as well. I didn't see much tranny tuning in your last file.

[LanceD]

yeah I'm just getting started and trying to learn as I go. I appreciate the help!