LS3 Knock Sensor Sensitivity??

[Jimmyz]

I'm pulling a lot of timing and I am to the point now where I feel it may be false knock. I've pulled timing out without much if any changes to the knock. Car has headers a cold air setup and that is it. Has anyone had these issues before? Are the stock knock sensors too sensitive? If so, what was your solution to the knock sensor settings?

[Russ K]

Yes, the LS2 & LS3 knock sensors are too sensitive. I double the decay rate table & halve the base attack rate table.

The new body style trucks with the 5.3 & 6.0 engines also have false spark knock.

Russ Kemp

[Jimmyz]

Thanks. I'll give that a try.

[BBA]

Yep, what he said. Russ is right.

I still see about 1-2 KR at times but no ping, no matter how I effect timing. I have decreased sensitivity, increased decay rate as well.

[Jimmyz]

Its working guys Mike and I put about 5* more timing and we're seeing no KR so far. We're gonna keep increasing the sensitivity until we see knock. From 19* to 25* is a nice SOTP bump.

[RWTD]

Wait a minute, you can't just do that safely. When you have false knock, you can't just blindly change the settings to "reduce" sensitivity, and then expect the sensors to give you any form of accuracy for tuning purposes. If you knew what went into calibrating the knock sensors you'd be shocked. You need to honestly be testing your spark changes on a dyno, otherwise you'll never know if you're getting instances of real detonation, which is not always audible (many times it isn't).

[EC_Tune]

Hey James,

The LS3 is too sensitive. Dyno proved it. I took a bunch of timing out, killed torque, and it still knocked. Thus the sensitivity adjustment.
I spent an extra 2 hours on the dyno just getting the sensitivity right on the LS3.

[RWTD]

Exactly, right on! Hence why I said "You need to honestly be testing your spark changes on a dyno".

[WS6FirebirdTA00]

Changes were not blindly made and you don't have to be testing spark changes on the dyno when you know what to look for. It may make things more simple but the road and the dyno are two totally different beasts. We made minimal changes on a less than stock timing table to get rid of the false knock and then played with the timing from there. They are still way too sensitive but any sign of knock will trip these things in a heartbeat. I am not about to just blindly change things like that

[Alvin]

I'm found the same thing. G8GT's, and 07+ trucks are especially bad. I had a 08 LS3 Vette on the dyno today that reported knock even with the timing back all the way down to 19 degrees.

[freemaSSon]

i was running 93 octane in an '08 Escalade and it would not even hold the STOCK table without showing KR so i added a bottle of MMT based booster and still got KR.....

this answers all the questions i had......i did notice that the sensors form my '06 TBSS are not the same as the '07 TBSS and the sensors in the Escalade appear to be the same as the ones as in the '07 TBSS so this helps LOADS.....DOUBLED and HALVED.....thanks

[Atomic]

How are the knock sensors on the 03-07 classic 5.3s?

[RWTD]

How are the knock sensors on the 03-07 classic 5.3s?

They are quite decent at the factory settings, actually.

[Sneakyws6]

Are these tables the ones under the Spark Control>Spark Retard tables in the Engine side of HPT?

From what I read Russ and the others are saying multiply the Knock Retard decay tables by 2, then the Knock Retard Attack tables reduce in half.

Is this right?

When I was logging I was seeing some KR when it was cool out in random places during just regular ole drving even when there was no audible knock to be heard and while running 91.

Made me wonder if it was flase knock or not.

[WS6FirebirdTA00]

that will only change how it comes in and goes out, not the sensitivity of the sensors.

[Harlech]

that will only change how it comes in and goes out, not the sensitivity of the sensors.

True but it does make a hell of a difference on driveability with the corvette. Anyone have a good writeup on tuning the sensor sensitivity down yet?

[WS6FirebirdTA00]

there are just two tables to adjust, I pull timing out, adjust the tables so there is no false knock, then try to go back at the timing I originally wanted

that leaves them more sensitive, but won't pick up false knock as much (still may)

[domestic rice]

Just to make sure I am changing the right one "Knock Retard Attack"--> then 1/2 the whole "Base Retard" table right? Mine does not say exactly what your does I guess, but I think that is the correct one.

[WS6FirebirdTA00]

no, the attack is not the sensitivity.

[domestic rice]

no, the attack is not the sensitivity.

Um would you mind telling me what is then. I was looking at what Russ said above and this table was the closest thing I could find on my 07 5.3.