Warhorse

I have recently developed significant KR in the lower RPM ranges. It is more prevalent as you reduce engine speed towards idle and during low RPM’s. While accelerating or steady cruise everything seems fine.
I have not changed anything lately and have no idea of what is going on with this erratic behavior. Can someone take a look at my scan? I also will include my latest tune.

BLOWNBLUEZ06

iTrader: (17)

I would raise the min MAP and RPM for KR. Are you getting your commanded timing when going WOT? Your burst knock tables seem to have low values and burst knock doesn't show up as KR. It will just remove timing. You might consider raising them.

BLOWNBLUEZ06

iTrader: (17)

I would raise the decay values too.

WAHUSKER

iTrader: (4)

Since it seems to happen a lot at a dead stop I look for a pipe rattling against something.

Warhorse

BLOWNBLUE ZO6
I have running with nearly this same tune for weeks / months and have not seen this before today.

WAHUSKER
I did not think that pipes, rattles or outside vibrations would be read by KR sensors. My understanding was that it takes certain frequences within the engine to set off KR readings. I'm not an expert by any means.

TS6

iTrader: (41)

Oh no, you can set off knock sensors easily with mechanical noise.

WS6HUMMER

iTrader: (19)

My all solid rear suspension is so noisy that I had to pretty much do away with my knock sensors. It turned the whole car into a stethescope.

tomz28

iTrader: (20)

valvetrain can set off the knock sensors as well sometimes

BLOWNBLUEZ06

iTrader: (17)

Well, I see no reason for the PCM to monitor for knock at idle or even while cruising and not under any boost and looking at your logs, I also don't see any reason for such a slow decay rate. I understand that it wasn't happening before. You can look for parts rattling that are causing it, check everything with an engine stethoscope, inspect your knock sensor wiring from end to end to find your problem, but I still don't recommend values that monitor for knock when the engine isn't under much load or boost or such a slow decay rate. The burst knock will not show up so easily. It will just kill your power by changing your commanded timing and you will have to dig for it. When you fix this problem, go and romp on your car and either make a histogram of your delta cylinder air values, export your log to excel and calculate it or see if your timing is less than commanded. I had a problem and was losing over 50rwhp due to the burst knock table values being too low.

moehorsepower

iTrader: (3)

Can you actually hear the knock? or is this just on your scanner, Could be something failing such as your knock sensor, will not throw codes untill dead. Also could it be carbon build up? we had a car in the shop one time for cam install, sat around for a couple of weeks. After the mechanic was done, started the car and it sounded just like a rod was knocking, yes it was that loud. We could not figured what the hell happened, the mech said that it might be carbon build up in the heads, I said no way, well he was right...

BLOWNBLUEZ06

iTrader: (17)

at idle too?

maxgee

iTrader: (5)

That's a lot of knock a low speeds and idle...definitely think it's a mechanical issue, nothing with the tune. Although the suggestion about your decay rate sounds viable. Check the mechanical condition of your car.

Warhorse

I cant really detect any noise in the engine. About three weeks ago immediately after an oil change, the engine during idle and off idle rpm's started making a sound and frequency very similar to lifter sticking. Similar but not exactly, sound was not a sharp tick but more of a wipe or revolving motion and would come and go. Drove to a local shop with lots of LS experience and they also could not pin the sound to a specific location. Intent was to drop off truck on the following Monday and let them dive into it but over the weekend the sound suddenly stopped as quick as it began.

Today I performed more scans. I reduced timing as much as 10* through the entire range and still recorded substantial KR. Most was below 2000 rpm's.
When under acceleration and in boost I see no KR.
Definitely something going on. I am still at a loss for what.

moehorsepower

iTrader: (3)

Yup, especially at idle, it was knocking so hard we were afraid to rev it..

moehorsepower

iTrader: (3)

Like said, no exhaust touching anything? my own car detects knock at idle but if I give it a little gas.....gone and nothing at WOT, My supercharger was just so close to the heads that it was detecting the slight touching of the case to the heads...

Warhorse

Is it possible the sensors could pick up anything in the torque converter or transmission to cause KR ?
My heavy duty truck mechanics seem to think they hear some sort of rattle in the torque converter area after removing dust cover.

crf538

iTrader: (3)

i was getting the same thing, i took some sensitivity out of the knock sensors and it was fine ( about 30%) , its pretty common to have to do that if you search around...

1BAD_LS1

iTrader: (36)

I have this problem also... when my converter locks up at light throttle. also when I take off from a stop.