I took the truck for another drive and pulling out from a side road I gave it some throttle and it actually ripped the tires for about 4 seconds. I have heavy 22" rims on this truck and it was surprising how easy it spun. Maybe the burst knock change with new sensors has it actually doing what it's requesting, just saying it seemed to have took less throttle to carry on like that than before.
Now that you have seen it work, I'd be curious to see if changing the Burst Knock back to 0.00g/s would 'break' it again. There's lots of undocumented stuff that can happen when we go poking around in a PCM, stuff the service manuals don't have any reason to account for or even consider.
I might switch it back and see but I don't recall changing anything in there to 0 and I pay close attention and save new changes with discriptions but will let you know. Also when I drive the rig again I will update if the pinging sound is still there.Originally Posted by blindsquirrel
Thanks
Burst Knock was set to 0.00 before the knock sensors started working.
Yes indeed it was.
So what made it start working again? Was it fixing the Burst KR table or something else? I want to know what it was, I just thought that maybe if you could do an A-B-A test with the only change being that one table, it would help me understand why this all happened in the first place. It would be good to know if doing the Burst KR table wrong can have other unanticipated effects. I only want to be able to give better answers to the next guy that's having problems.
Sure, I can do that and let you know. I know when I started getting the PO332 code for the KS I went in and disabled them in engine diag with HPtuners and that was for a couple months until I got all the new parts. After replacing everything I switched them back on and no codes or check engine light so figured all was fine until I started hearing the pinging under light throttle. Maybe when I just write calibration and not write entire somethings don't go all the way. I will switch it back to the last file with Burst Knock at 0 and let you know.
Hey, so I drove the truck today and listened for the pinging sound and it wasn't present at all. I loaded the file with Burst Knock values at 0 and took it for a drive, the only KR was short 1 second spikes which didn't look like anything and the pinging was present when pressing lightly on the throttle even when KR spikes weren't present. Loaded back the file with Burst Knock normal and when KR is present it looks real not just short spikes but there was no pinging sound whatsoever.
I guess having those tables 0 out affects the operation of the KS and causes pinging sounds thus leaving them inoperable and messes with the actual timing the PCM is requesting. The truck really feels much better with those tables fixed and the KS's doing their job so I will start fine tuning things again once I get my wide band sensor so it will be accurate. I have attached both logs with burst knock 0 and normal to view.
Thanks again
Excellent piece of data, thanks.
I suspect it's this: When Burst Knock is active, actual KS activity is ignored. In your case, having Burst KR active all the time, and pulling 0*, had the effect of disabling knock detection altogether. None of this is described in the service manual because having it set up like this is not a condition GM ever has to account for.
Just so you know, burst knock isn't going to be useful for you, it's safe to disable it (set the entire table to 8.00g/s). Burst KR is based on worst-case predictions, like the typical owner who buys the cheapest garbage fuel they can find, never changes the oil, puts off having spark plugs replaced until it's misfiring on more than 2 cylinders, lives with the CEL on constantly because they figure it's some dumb meaningless issue they won't ever understand that'll cost a lot of money to fix, etc. For those drivers, burst KR steps in and pulls some timing just in case it's needed - no matter if it's never picked up any actual knock at that point ever before.
If you're not the typical dirtbag owner (you're here, and looking at stuff inside the PCM, so you're definitely not typical) who neglects everything, just turn burst KR off completely.
Thanks blindsquirrel,
I like your explanation of typical owner with cheap gas etc.. I know a bunch of people who ignore all those things with vehicles which is crazy..Makes me mad when I offer to help them with scanning it to confirm the problem and they just say "it's driving fine and will get it serviced soon but thanks" and they never intend to.
Cheers
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