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hello, i have a 2018 silverado. 6.2L. 100% stock. i have done the MAF and SD tuning with a wideband. i am on timing now and the knock above .44g is out of control. i cant get it to stop. the knock sensors were at 3.5 stock. up to 6 right now. all the help would be appreciated. :yay:Attachment 106522Attachment 106523
Post up your Tune and Some logs and you will get much better response...
Agreed post tune if you can.
What fuel?
ok. using 87 fuel for this tune. i know 91 or 93 will be better, but i want to dial in 87 then ill move to 91. thanks
87 knock pretty good on stock and reverts to low octane table fairly quick which makes it a dog... my guess is you changed spark and you shouldn’t have
Um... so who copied the high octane spark table into the low octane table?? The two are exactly the same.
Bingo!! Figured that was the cause..
The ECM is trying to protect you lol
this guy... so since im not doing it right can you tell me how? i thought i was supposed to have them the same for tuning. what table should i be adjusting?
..and we wonder why GM doesn't want people messing with tuning anymore...
What you've done here is forced the timing advance to the high octane settings, and you're running fuel that is not high octane. So, the engine is knocking, and the ECM is reporting knock retard. What you need to do is adjust both spark tables downward in the regions that are different between the OE "low octane" and "high octane" tables to get rid of the knock retard, and you can consider what you come up with the new "low octane" timing table.
Then, you put in the highest octane fuel you can find, start working upward from your new "low octane" timing table until you start to see KR set in, then back it off.
If you want to be safer about it, you start off tuning with both timing tables set to the "low octane" settings and work your way up. The whole point of setting "high octane" and "low octane" tables to the same is to eliminate any knock factor adjust the ECM might do while you're logging and tuning it.
ugh...iirc the tuning school genv book says to do this...im new to tuning myself and wondered how this could be correct.Quote:
Originally Posted by blindsquirrel
I wouldn’t let the tuning school tune my bicycle
It's to remove the element of how knock factor skewing might affect calibration of the timing tables. On most calibrations, when you cold start your vehicle, the knock factor gets reset to zero, which means the ECM is using the "high octane" timing table as the starting point for all timing calculations.Quote:
Originally Posted by WolfgreySS
As the vehicle is driven, if knock retard is detected, depending on how much it is, and how the knock factor adjustments are calibrated, it will start moving towards 1. If there is no knock retard detected, it starts drifting back towards zero. The ECM interpolates between the "high octane" and "low octane" tables depending on this value (0 = high octane, 1 = low octane). This is how the ECM is able to dynamically adjust for varying fuel quality, operating conditions, etc.
If you're attempting to calibrate / optimize the timing tables, this knock factor skewing can make it really challenging (like hitting a moving target), so by copying the "high octane" table to the "low octane", you effectively remove the ECM's ability to skew the timing based on knock retard.
Copying "high octane" to "low octane" means the ECM is running "high octane" timing. This can be dangerous to your engine, particularly if you're running low octane fuel on an engine that prefers higher octane fuel. It's safer to start with something in between and work up towards more aggressive timing.
What transmission is in it and rear gear ratio?
All 6.2's after 2015 come with 8L90e transmissions and his truck has 3.23's in that tune.Quote:
Originally Posted by 2xLS1
Keep the converter unlocked in gears 1-5 and 6th below 45, 7th below 50, 8th below 55, and I bet the knock will go away. If it does then you could test re enabling lockup in 5th at 40 but keep it unlocked in 1-4.
thanks for all the help from everyone. my first problem was that i copied the high octane table to the low octane table :eek:
any help with telling me what channels i need to log to see where timing is being added or removed. right now i only have timing advance sae logged and it is 5 to 12 degrees higher than the low octane table. i did copy over the low to the high octane table so i can get a base table :worship:
Try these channels out. This my base channel set that I pare down depending on what I'm wanting to log so there's alot of them here. Can definitely remove some once you know what's going on.
Attachment 106638
Yeah I got suckered into that too. Bought them because I THOUGHT I was doing something wrong when i wasn't.There is some okay information in there.....some,but when I asked for help setting it up in lambda instead of AFR they pretty much skirted the whole question with some generic response. They were no help AT ALL.Quote:
Originally Posted by Ben Charles