hohl

I posted something about this in the PCM forum but know that we have several people in here that have swapped their 5.3 for a 6.0 or LS1 so I am looking for advice on how to attack knock retard in cells 14 and 15.

I swapped LS1 for my 5.3 and am using the truck PCM, intake, accessories, etc...

I fattened up my truck by changing the IFR by 95% and the ltft's are all zero or slightly less but I am experiecing a lot of KR between 1800 and 2400 RPM under normial driving conditions. The logs show this to be in cells 14 and 15. I know those are PE cells but should I add PE or edit the MAF? How have you guys done it?

parish8

iTrader: (6)

first, can you hear any pinging? if you can't you should try some race gas to check for false knock, if it still has KR after you put in some 100octane then it is false knock and adding fuel wont help.

hohl

I don't hear any pinging at all. I just feel the power loss from the timing being pulled away. When looking at my O2 voltages while in those cells, they are way low, ~750. I think richening up the PE should at least give me some data to see if it improves.

How common is fake knock? Is there any way, besides turning the KS off, using one of the KO Boxes, or the desensitizing hack, to tune for it?

parish8

iTrader: (6)

how much throttle are we looking at here? if you are at full throttle and seeing only .750 you are way lean. there is no way to tune for false KR, i have tried, best to "hack" it one of those ways mentioned. not sure how common false knock is but a few of us have had to work around it.

parish8

iTrader: (6)

after looking at your first post it looks like you are not at WOT since your rpm's are so low, if your not at WOT or near it you wont be in the PE. what is IFR?

edit...doa, injector flow rate? by adjusting them down that would richin up your WOT fueling but not your part throttle. your computer would just learn and adjust them back to 14.7-1 at part throttle.

hohl

From what I thought, WOT was defined as high load situations not on Throttle Position Angle. How else would I be getting into Cell 15 at 2200 RPM and 30% TPA?

Also, no matter how rich or lean I make the engine by editing the IFR, the PCM will adjust to 14.7? So will the ltft's work there way back up to positive numbers because the PCM want's to maintain 14.7?

I am starting to think that the only way I am going to get rid of the low RPM, low TPA KR is by editing the MAF. Am I wrong?

parish8

iTrader: (6)

the engine is adjusting by moving the ltft's if you had positive ltrims and wanted to move them down into the negative numbers you would adjust your IFR lower. you will still have exactly the same fueling at part throttle once the computer learns all the ltrim numbers, it always shoots for 14.7-1 untill it goes into power enrichment mode.

by adjusting your IFR so you have negative ltrims this helps when you are ready to adjust your WOT PE stuff. from what i understand you go int PE when you see a certain throttle position, like 85% or somehting. you will see the 02's go rich and stay there, like .85 or higher.

like i said before, find out if you have real knock, then if you do i think the only adjustment you can make it to pull some timing, not sure if you can add fuel at part throttle. i really dont worry about a little part throttle KR, just try and avoid any WOT KR.

hohl

Thanks for the help Parish8. I got the chance to run it with some octane boost and found the same KR. It looks like I am a victim of phantom knock. Any suggestions on how to best handle it?

It's going to have to be a while since I blew up my rear diff while "tuning." Don't know how it happened, I am not making that much power.

Did you lose yours before going to the eaton?

parish8

iTrader: (6)

you want to make sure it is false knock before you try and get rid of it. what od you mean some octane boost? those little cans of stuff do very little, you need to put in some 100octane unleaded.

my eaton didn't die, i still have it in the garage.

hohl

Since the nearest station with 100 octane unleaded is nearly 40 minutes away. I used the a 20% Tuolene mix from gnttype.org
Put 2 gallons in with an 8 gallon fill-up. So I was no less than 17% or so -- I figure that it takes me to about 95 something when all is said and done.

With that fuel and no audible knock, I figured it was safe to assume I had false knock. I'll try the 100 octane when I fix my diff.