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I'm swapping a LS3 into my 04 CTS-V that originally had a LS6. I have the racetronix knock sensor wiring harness.
I changed the signal wires like efilive says, this harness has grounds for each sensor that bolt to the block but efilive shows 2 signal wires & 2 grounds at the pcm. Should I be hooking the grounds to the pcm instead of the block?
This is what efilive shows:
"The PCM can be used with two types of knock sensors, this parameter allows you to select which type of sensor is fitted to the engine.
The standard LS1 sensor is a resonant type, these sensors are connected like so -
Sensor Bank #1 - J1,pin51
Sensor Bank #2 - J1,pin11
If the engine is fitted with flat response sensors (like the LS2 uses), then the connections are like so -
Sensor Bank #1 GND - J1,pin49
Sensor Bank #1 Signal - J1,pin09
Sensor Bank #2 GND - J1,pin50
Sensor Bank #1 Signal - J1,pin10
Only the following values may be entered into this table:
- Resonant (LS1)
- Flat Response (LS2)"
I've read some issues getting the tuning right with the LS3 knock sensors. Some say to copy the S10 4.3 as a start since it had a flat response type sensor.
Has anyone made out ok with this? I was to run the LS3 style because I'll have limited clearance with my headers & I already have the harness & sensors. Hope to figure this out to help people who do this in the future as well.
I hope people answer this, every time I try to bring it up everyone's answer is always "just tap the block and run resonance type". Also those pins are not where the so knock sensor signal normally is in a 411
Last edited by maroonls1z; 03-23-2015 at 01:09 PM.
The engine is going in tomorrow. Will be testing more but got no real answers other than just play with the tune. I was hoping to find someone who has done this and was successful.
I am following with personal interest as I have a new LS3 with 24x reluctor and am using the 411 PCM. Not wanting to drill/tap the LS3 knock sensor holes for the bigger LS1 knock sensor threads, I currently have my LS1 knock sensors mounted on the very heavy-duty (1/4" thick steel) Holley swap mounts. (My headers would also interfere with the tall LS1 sensors in the stock position.)
The problem with non-stock sensors or mounting position is that it is hard to test whether it works, as you normally do not get a knock signal. And it is risky to purposely make the engine knock for the purpose of checking and tuning the sensors.
I am following with personal interest as I have a new LS3 with 24x reluctor and am using the 411 PCM. Not wanting to drill/tap the LS3 knock sensor holes for the bigger LS1 knock sensor threads, I currently have my LS1 knock sensors mounted on the very heavy-duty (1/4" thick steel) Holley swap mounts. (My headers would also interfere with the tall LS1 sensors in the stock position.)
The problem with non-stock sensors or mounting position is that it is hard to test whether it works, as you normally do not get a knock signal. And it is risky to purposely make the engine knock for the purpose of checking and tuning the sensors.
I agree it's a risk to make it knock so it can be tuned.
BlackSS/SC: which knock sensors are you using:
GM #21024981 (ACDelco #213-924) - Listed for 2004 4.3L S10
GM #12623730 (ACDelco #213-1576) - Listed for various LS2 engines
The Racetronix harness in the picture has a connector matching #12623730 (LS2) while the other (4.3L) has an EV-1 connector (like an injector).
Does anyone know if they are electrically identical and only different in their body and connector? Otherwise if the LS2 sensor is used, I wonder how accurate the 4.3L S10 tables will be.
Well pat wasn't able to make these work. He changed that knock tables to match the 4.3l s10 and it showed knock all the time. That's about it.
Is there anyone else that can help with this? I've been thinking about adding ls1 sensors somehow but I'd probably have the pull the engine to tap the holes for them.
Well pat wasn't able to make these work. He changed that knock tables to match the 4.3l s10 and it showed knock all the time. That's about it.
Is there anyone else that can help with this? I've been thinking about adding ls1 sensors somehow but I'd probably have the pull the engine to tap the holes for them.
I went through all of this doing my swap....Ls3/3 sensors never seem to work right in the ls1 pcm even when everything is swapped correctly. I have ls1 knock sensors in mine and you could do the same but even those are marginal at best. After talking with a number of tuners most just delete the sensors. The ls1 sensors in that location usually dont pick up much and if you increase sensitivity they begin to pick up false knock.
I know thats not the answer you want to hear but its what a lot of people do. As long as the tune is safe and you run a quality fuel you shouldnt have issues. My sensors have the stock tables in the pcm and I have seen small retard at certain points but thats it. Formato tuned it and said it was fine, same thing was said by katech and slowhawk. They all have issues using sensors and just tune them out
ya pretty much lol with mine i tried increasing sensitivity 20-25% and i got a lot of false knock in random places were talking 4-7 degrees. if it was really that bas i would hear it and the motor was smooth. then i backed it down to 15% over stock and got nothing, just like the stock tables were reading. so it was either very little or a bunch of false knock. I didnt want to take slowhawks or the others word because i like the idea of knock sensors but in the end they were right lol
You may need an OS which was originally made for Flat-Response sensors, sometimes changing a table in the calibration doesn't make it work, it must be enabled in the operating system so the hardware reads the correct pins from the harness and does the correct signal processing.
HP tuners has the option to change to flat-Response and going to ground on the block is fine. You are just doing what the computer is doing internally... I've never ran on the street with them in but never seemed to see issues on retarding spark when going through HP tuners and looking at data with tech 2.
03-22-2015, 08:05 PM
LS3 knock sensors in swap - tuning help 
