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I've noticed that my spark advance is very shaky as I get into boost. It seems pretty smooth when I'm just driving around with lower load. Is this normal? Thoughts?
i've tuned a couple 08 z06's that did something very similar until i disabled "spark smoothing"
they were both heads/cam cars that had the same saw tooth timing. this was at light load though and caused surging when cruising. as soon as I disabled spark smoothing it lined out
If you look at the 3rd graph it shows the retard parameter. it says zero at least for this pull.
I do frequently get knock retard on this car but I feel like it's just the sensors picking up something buzzing. The timing is pretty conservative. 10 degrees at WOT on 7psi
I'm surprised the car even pulls with 6 degrees. I'd make sure the low and high octane tables match and zero out any scalars or adders and give it more reasonable timing what transitioning to and in boost and see what it does. Also I typically bump up the retard recovery rate so it puts the timing back in immediately when "knock" stops.
Yea I mean it still pulls, but it's gotta be down close to 100ftlb. Used to spin the tires at the top of 3rd now it hooks the whole time.
I guess I was just worried it might actually be knocking so I pulled a bunch out. I still need to trace down the gremlin that's causing the issue.
What's standard for an LS3 with under 10psi, 12 degrees?
You're down probably 6 or 8 degrees depending on cam and other stuff so that's 100whp, makes sense. You can get knock from an overly rich and under timed setup too. You really need to read a fresh set of plugs after a pull to see what the motor wants. Normally you should be able to get 12 degrees out of it or more with 93.
Yea I'm wondering if the slightly erratic map signal is causing burst knock to activate. That was the next thing I was going to look at, so thank you, I will log that.
From a general stand point, I know I will have to get on a dyno to get my spark really dialed in, but how does this high octane table look directionally? Am I on the right track with this? I bumped up my higher load spark to 10 deg, not sure about the rest of the map but I assumed it should be basically stock spark out of boost.
I always max out burst knock so it's disabled. Timing looks ok to start. You can get a feel on the street with a couple pulls and then pull the plugs and look for the timing mark on the strap, any speckling on the porcelain and number of threads with color.
I wanted to close the loop on this thread, so yes disabling burst knock helped a ton:
Only odd thing I notice is that the final timing advance tends to be more than I ask for in the high octane table. I'll have to track all of the different adders and see which one is adding to the advance.
I wanted to close the loop on this thread, so yes disabling burst knock helped a ton:
Only odd thing I notice is that the final timing advance tends to be more than I ask for in the high octane table. I'll have to track all of the different adders and see which one is adding to the advance.
Do you guys like to use this table, or do you tend to zero it out? I can see how this would be very useful to use, I imagine I would just take it into account when filling out the base high octane table? I think its safe to assume whenever I'm about .8g/cyl I'm going to be in PE anyway. Do these engines like additional timing when the mixture gets richer?
I zero it out to make it easier to manipulate the other tables when tuning, less to keep track of. Timing is combo dependent but I don't generally add timing based on commanded A/F ratios.
Thanks Nic, yes zeroing it out will definitely make it easier to write the spark map. I really appreciate the help, how the car runs now vs even a 3 weeks ago is night and day. I owe a lot of that to you guys here.
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Saw tooth spark 
