Ls3 swap, Knock sensor and timing question
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
Ls3 swap, Knock sensor and timing question I am using HPTuners and is still learning as I go. How do I test my knock sensors to make sure they are working? Something simple like a tap on the head/block with a hammer should set them of?
I just got the car running and want to start tuning this weekend.
How much timing can I start with?
Idle: 19-22?
WOT: 23-24?
And what about part throttle driving... Can I just copy the LS6 timing tables?
Ls3 in a C5Z using LS6 24 crank wheel, knock sensors, map sensor and LS2 cam sensor and throttle body. All wiring adapters from Casper Electronics.
Pic of the knock sensors
I just got the car running and want to start tuning this weekend.
How much timing can I start with?
Idle: 19-22?
WOT: 23-24?
And what about part throttle driving... Can I just copy the LS6 timing tables?
Ls3 in a C5Z using LS6 24 crank wheel, knock sensors, map sensor and LS2 cam sensor and throttle body. All wiring adapters from Casper Electronics.
Pic of the knock sensors
Last edited by Z06VENOM; Apr 22, 2015 at 08:42 AM.
Moderator
Joined: Aug 2010
Posts: 7,322
Likes: 528
From: Ann Arbor, MI
Knock sensors look for vibration in a specific frequency range.
I had to do something similar with my new LS3 (24x) running a 411 PCM.
I increased the sensitivity of the Knock sensor tables by reducing all values by 2.0. I then started getting Knock Retard during modest accelerations. That convinced me they were working and I therefore restored the original table values.
Obviously not a foolproof experiment
(Again, I'm not an expert here, just sharing my single experience.)
I had to do something similar with my new LS3 (24x) running a 411 PCM.
I increased the sensitivity of the Knock sensor tables by reducing all values by 2.0. I then started getting Knock Retard during modest accelerations. That convinced me they were working and I therefore restored the original table values.
Obviously not a foolproof experiment
(Again, I'm not an expert here, just sharing my single experience.)
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
Knock sensors look for vibration in a specific frequency range.
I had to do something similar with my new LS3 (24x) running a 411 PCM.
I increased the sensitivity of the Knock sensor tables by reducing all values by 2.0. I then started getting Knock Retard during modest accelerations. That convinced me they were working and I therefore restored the original table values.
Obviously not a foolproof experiment
(Again, I'm not an expert here, just sharing my single experience.)
I had to do something similar with my new LS3 (24x) running a 411 PCM.
I increased the sensitivity of the Knock sensor tables by reducing all values by 2.0. I then started getting Knock Retard during modest accelerations. That convinced me they were working and I therefore restored the original table values.
Obviously not a foolproof experiment
(Again, I'm not an expert here, just sharing my single experience.)
How much timing did you end up with?
Moderator
Joined: Aug 2010
Posts: 7,322
Likes: 528
From: Ann Arbor, MI
My LS2 with a 231/239 cam and CNC 243 heads had a best trap speed with 27* up to 4800rpm and 28* above that.
I haven't had a chance to take my new LS3 stroker with 239/251 cam to the track. I'm just running 24* up to 4800 and 25* above that now.
As I understand it (and I am no expert) higher overlap cams work best with a few more degrees of advance. In other words, my values are likely too much for a stock-ish cam.
I haven't had a chance to take my new LS3 stroker with 239/251 cam to the track. I'm just running 24* up to 4800 and 25* above that now.
As I understand it (and I am no expert) higher overlap cams work best with a few more degrees of advance. In other words, my values are likely too much for a stock-ish cam.
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
My LS2 with a 231/239 cam and CNC 243 heads had a best trap speed with 27* up to 4800rpm and 28* above that.
I haven't had a chance to take my new LS3 stroker with 239/251 cam to the track. I'm just running 24* up to 4800 and 25* above that now.
As I understand it (and I am no expert) higher overlap cams work best with a few more degrees of advance. In other words, my values are likely too much for a stock-ish cam.
I haven't had a chance to take my new LS3 stroker with 239/251 cam to the track. I'm just running 24* up to 4800 and 25* above that now.
As I understand it (and I am no expert) higher overlap cams work best with a few more degrees of advance. In other words, my values are likely too much for a stock-ish cam.
Ok, I lowered the timing everywhere (from my heads and cam LS6 tables) with WOT down from 28* to 23*max plus reduced the knock sensor tables (by x .9 and again by x .9)
Done some logs over the weekend...
Now I see some knock (2*- 3*) showing up in the Display Chart but nothing in the spark knock histogram?? Could that be knock burst?
And there is something not right about the spark knock histogram... The CylAir only records up to .5 but in the Display Chart it shows that it recorded much higher than that?
Also in the Display Chart it shows 24.5* (right before knock) but I only demanded 23* in the timing tables, both high and low octane? Is the another table it uses for timing?
Any idea what I am doing wrong?
I posted the log and tune files on HPTuner forums but no response yet😔
Thanks again
I was curious about this as well...I'll try adjusting the sensitivity.
So far I'm reusing my timing table from the ls1 with basically the same cam and heads and it seems fine but I haven't been able to get any KR so far whatsoever which I find suspicious.
I did go to a tr6 plug if that makes any difference. No audible knock either.
So far I'm reusing my timing table from the ls1 with basically the same cam and heads and it seems fine but I haven't been able to get any KR so far whatsoever which I find suspicious.
I did go to a tr6 plug if that makes any difference. No audible knock either.
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
Same here... TR6 plugs.
As far as I know the LS3 heads needs less timing than the LS1/6...
Another question... How much Cyl/Air should I see in g/cyl WOT? Trying to figure out the knock histogram readings.
It's a built LS3, PRC heads from Texas Speed and a 226/238 .605/.612 cam, LS3 intake, LS2 throttle body and LS7 Air Raid cold air.
As far as I know the LS3 heads needs less timing than the LS1/6...
Another question... How much Cyl/Air should I see in g/cyl WOT? Trying to figure out the knock histogram readings.
It's a built LS3, PRC heads from Texas Speed and a 226/238 .605/.612 cam, LS3 intake, LS2 throttle body and LS7 Air Raid cold air.
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Verdad Gallardo Moderator
Joined: Aug 2010
Posts: 7,322
Likes: 528
From: Ann Arbor, MI
Glad to hear you are making progress.
I didn't want to post any more "info" because I am still learning how to experiment with Knock sensor sensitivity and seem to be having some intermittent problems with them.
I didn't want to post any more "info" because I am still learning how to experiment with Knock sensor sensitivity and seem to be having some intermittent problems with them.
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
I ended up making them more sensitive by multiplying the table by .9 from stock LS6 settings.
Seems to be working ok for me.
Thanks
Thread Starter
Staging Lane
Joined: Oct 2012
Posts: 53
Likes: 0
From: Ontario
My headers are also HTC coated so I am hoping it's enough. Keeping a close eye on it. 100 laps so far and still good👍
