Big KR numbers?

[Mstansbury0704]

I am seeing some crazy KR on different logs that don't make sense to me one being 6.9 degrees pulled at a medium load low rpm scenario, Then ill log again on same day and get no knock in the same region but some in a a different region. When I Initially established my lower rpm VE table and finished up my MAF curve I recorded a long drive. I seen very little to no KR and fuel trims all looked decent, Now all that I have done in the tune since then is re-enable my DFCO and smooth my VE table using the smoothing function, and I reduced my Follower and Cracker tables to help with some low speed bucking. Now, I am getting a large amount of knock retard as shown in scanner, during 6th gear cruising usually at 1600-2000 rpm however I think it only happens after it is in a steady state, as ive tried to entice it to happen and I cant, it will just randomly pull large amounts of timing after cruising for 10-15 minutes... I thought maybe I smurfed my VE, but using the compare feature it really didn't remove or add that much fuel to the cells from before. What gives? Ill attach a few logs and the two tunes, hopefully somebody can help me determine if this is false or real knock and if I should pull timing, hunt for vibrations, etc... I do have a loud valvetrain, big cam, dual valve springs and morel lifters, unsure if aftermarket heads with bigger valves also transmit noise differently so ill include those..
final tune, VE smoothed DFCO on TC&TF adjusted KR present 2.hpl
final tune, VE smoothed DFCO on TC&TF adjusted KR present.hpl
Final Tune VE smoothed DFCO on TC&TF adjusted.hpl
VE Smoothed, DFCO on Throttle follow 2000 to 0 zerod TC reduced low rpm&speed area.hpt
Final tune DFCO On.hpt


Here are some logs and the two tunes that show my only changes to the tune, one of which is pulling a degree of timing from the 1400 rpm cell due to some slight kr I noticed in a previous log. and the other being smoothing the VE table and reducing my cracker and follower tables. Hopefully someone knowledgeable can take the time and chime in.

[jmanson62]

Mstansbury, do you have a non oem air intake on this? I have read numerous times about the MAF being very picky of its home and changing the pipe and or location of the MAF can have ill affects on KR. I too am having this problem at the moment but I am stock 5.3 with a custom intake tube.

[Mstansbury0704]

I have a non oem maf as in my original metal air foil type one failed and they had been phased out by the plastic card style which I believe is actually an 85mm maf? So that?s the only difference. Slp lid and smooth bellow. Also if you mean intake manifold it?s an ls6. Have been eyeballing the fasts as I pull quite a lot of vacuum at wot

[5FDP]

Disable burst knock, see if it helps. I always disable it on modded engines, it gets in the way.

Also making both timing curves the same doesn't help either. If it knocks and then it goes away, the computer will slam all the timing back in at once, which can lead to more knock. The low octane curve needs to have less timing so it can use the knock learn factor to pick the timing between the two tables, then slowly work it's way back to only the high octane table.

Couple side notes, if you upgrade to the speed density enhanced OS you will remove the secondary VE table. It will make it faster to VE tune and the MAF still functions like stock even in a speed density OS.

I'd also keep the LS6 intake before wasting $1,000+ on a full fast intake/throttle setup. The dollar to horsepower gain just isn't there if you ask me. Many tests have been done on various intakes to show gains vs costs. Maybe consider a larger throttle body first.

[Mstansbury0704]

I never knew that about the different OS..is that what you normally do? That would definitely make dialing in the VE faster. I always assumed that speed density OS meant Speed density lol and I thought my burst knock was 0d out. Also for the timing tables. Would you recommend say making a blanket reduction? Say 5 degrees removed from all cells in low octane table? And I figured I?d see atleast 20 whp from a fast just due to the fact I see about 90-91 kpa on a WOT. Plus the aftermarket heads and big cam would actually flow with the fast. Anyway you?d recommend making sure my burst knock is disabled and reducing the low timing table to get the pcm some control over timing adjustments?

[5FDP]

Yeah, I always apply an upgraded OS if I'm dealing with a vehicle that has the secondary VE table. Make my life easier to only have just the primary table like all 2001+ operating systems.

Burst knock won't be zero'd, you need to max out the table at 8.000 so it's not active.

Do you live pretty high in elevation? That could also be a cause for lower MAP readings.

[Mstansbury0704]

That?s a good idea. Would definitely make things easier on me. I might try to change the OS to that. I don?t have the laptop in front of me but I thought it had a table for burst knock that had all 0s in it. Either way I took all my timing and took out 5 degrees in the low table excluding the idle cell areas. And I would see logs of map kpa during pulls and around 4,000 it would start to drop as rpms rose. I have done a log from a full pull to 6600 and kpa was at 91 at the end so it?s not choking out but definitely Wanting more air than available I think.