I'm trying to tune the timing on my car and I've noticed that the timing curve has an odd shape. It's sort of has a sigmoid shape. Here's the plot of my car when it was stock. The timing is denoted by the purple line. It peaks at 27 deg at 3800 then falls to 22 deg and then peaks again briefly to 25 deg at 4900 and then falls back to 22 deg and then rather quickly advances to 28 deg at 6600.



And here's my current timing. It peaks twice at about 21 deg below 3000 and then falls to 10 deg at 4000 and then slowly advances to 16 deg at 6600.



I can't seem to reason out what is going on. Anybody else see this and/or understand why the timing moves around the way it does? Also does anybody know when the stock knock window begins and ends? I don't have access to this with my version of UpRev.

Here's the WOT trace of burn times stock vs current from 1600 to 6400:

Stock: 59,60,63,64,65,67x5,64x2,65x2,61,60x2,63x2
Knock strength was about 300-500 during the entire run, but I did not have knock phones at the time see if this was audible.

Current: 53x2,51,53x4,51,52x2,51,52,51x8,50x6
Knock strength is 0 and I hear no audible knock with the knock phones.

 

It's normal for less timing in the 4k range (stock or tuned), this is the 'knock zone' for the VQ and also where you'll find the most torque (less timing needed). On the 2nd map I assume you're F/I? The timing numbers seem very low for N/A, and even a bit low for F/I.

 

your timing should be lowest at peak torque. if your graph accurately represents your torque curve, your timing is left shifted from what it should be for optimum saftey.

 

I thought it might be the knock zone giving me the dip in timing, but the knock strength is 0 the whole run. How does the ECU know when peak torque occurs? Yeah, the 2nd graph is FI. The boost curve is blue. If I advance the timing any more on the high end I start getting a bump in the knock strength. If I keep going I get around 2 pings on the knock phones around 4500 - 5500 rpm. I'd like to keep knock strength 0 even if I have to give up some HP. I know the UpRev documents say that the knock strength is unreliable but I have yet to hear knock on the knock phones that wasn't preceded by a bump in the knock strength.

Nice pick up. My torque curve is actually shifted to the right by about 300 rpm because of the way I do smoothing.

Thanks for the responses. You gave me some search terms to use to improve my understanding of how this works. I came across:
http://ls1tech.com/forums/advanced-e...ing-101-a.html

 

It's not necessary reduced timing because of perceived knock...it's all related to the flow of the motor. It's more efficient (flowing better) and requires retarded timing to react max pressure in the cylinder at the correct time.