Knock retard on stock '11 Sierra 5.3

[BADFNZ]

So I'm slowly starting to tune my '11 Sierra with the AFM 5.3. I'm only making one change at a time, logging, then adjusting before I move on to the next change.

The first thing I did was adjust the PE table. I made it 1.18 across the board above 2500 rpm. After loading the tune and logging, I got 3-6* of KR starting at ~4400 rpm in 2nd gear and it never let up until I let off the gas. Logged again, same result. So I changed all the 1.18 to 1.2. Same result. Changed 1.2 to 1.25. Same result.

Then I said hell, I wonder if the stock tune shows the same thing. So I loaded the stock tune and sure enough, KR shows up in the same spot.

The truck is bone stock except a Magnaflow muffler (obviously not making a difference). I don't think its false knock, but I guess I have no proof. This is all on 89 octane, which might be the issue, but you'd figure a stock truck on a factory tune wouldn't show knock with any octane.

Suggestions?

[murphinator]

if its false knock stepping the gas up to premium shouldnt change it , if premium fuel lessens or eliminates it you have just determined your dealing with real knock

[AllGo'N'Show]

^^ What he said is best to help determine if real or not.

Who installed your exhaust?
Climb under and make sure everything is tight, no loose brackets or anything. Simplest fix can be over looked

Other than that I am learning as well, keep us updated on your 5.3's progress, can't wait to tinker on mine

[gn2beatu]

Have you disabled burst knock? Bet if you disable that it goes away. Read up on it.

[BADFNZ]

I have not disabled BK. I've read up on it in the past, but decided to leave it alone.

The muffler was a simple weld-in, so no brackets, hangers, or anything else changed.

I'll try the 93 octane to see if it gets better. I just can't believe I'd get KR on a factory tune with any octane on a cold Texas night. Considering how rich and passive these tunes are from the factory, it just doesn't seem right.

[murphinator]

I just can't believe I'd get KR on a factory tune with any octane on a cold Texas night. Considering how rich and passive these tunes are from the factory, it just doesn't seem right.

I dont think i have ever scanned a stock gm vehicle that didnt have a fair amount of KR - especially normally aspirated stuff , I have seen over 10* on several different bone stock vehicles

[Kyne]

They have really sensitive knock sensors. I've seen the same thing on a 2009 5.3. I can't remember but off the top of my head they were set to 120 hz? Stock ls2 is 400 I think.

[AllGo'N'Show]

Have you disabled burst knock? Bet if you disable that it goes away. Read up on it.

Hi gn2beatu,

I'm working on my 5.3 as well, although 2003 but you seem to have great results with burst knock being removed and so do alot of people you have helped . I have done some searching and still am but just wanted to check if the tables I have zero'd out in the picture is all that is needed to check and see if that is the knock issue? I thought a picture would be a better reference for future search people as well



Thanks!

[BADFNZ]

I added 93 octane and the KR decreased, but it's still present. So it looks like it's the real deal.

[AllGo'N'Show]

Well I did similar, added a full tank of Shell 91(highest in the area without Husky 94 (10% eth) and alot of my knock and timing pulling is gone with Burst set off and Recovery quickened but I still have a tiny bit, so I guess I may have a mechanical issue. I have new knock sensors going in anyways as I want to wash my motor so maybe that will help with the last bit. Thanks gn for the burst info.