Can somebody explain to me the spark smoothing parameters?

[Martijn]

Hello, Everybody, Im tuning my new ls7 build. It has a cam with 17 degree of overlap.

I have discovered that the bucking has become much less when I have enabled the spark smoothing.
I think the engine can run a lot smoother during light load if I adjust the parameters. Can someone explain the parameters to me? The parameters I can adjust are:
Max torque delta
Max torque bias
Max torque loss
low torque gain.

I'm especially curious about what is meant by Max torque bias.
I am curious about your explanation.

Thank you,

[edcmat-l1]

Hello, Everybody, Im tuning my new ls7 build. It has a cam with 17 degree of overlap.

I have discovered that the bucking has become much less when I have enabled the spark smoothing.
I think the engine can run a lot smoother during light load if I adjust the parameters. Can someone explain the parameters to me? The parameters I can adjust are:
Max torque delta
Max torque bias
Max torque loss
low torque gain.

I'm especially curious about what is meant by Max torque bias.
I am curious about your explanation.

Thank you,

I don't know that anyone "tunes" the spark smoothing. With a big cam, ESPECIALLY the LS7s, you just turn it off.

[Martijn]

That is what I thought. But after I switch it on the car drive a whole lot smoother.
So I what to see iff I van make it even better by tuning the parameters.
Ofcaurse I could just try, but It would save me a lot of time and frustraties iff I know what the purpose is off these parameters. For most of them I think I know what they doing but I have no idea what the purpose is of the max torque bias. So who off you guys know?

[RobZL1]

https://forum.hptuners.com/showthrea...ing-parameters

[Martijn]

I saw this post aswell, but it does not explain the purpose off max torque bias.
Anybody an idea??

[SiriusC1024]

Where does it occur? Post the tune and log. A lot of times it can be adjusted out in the spark tables, especially idle/base transition.

[RobZL1]

I'm not 100% sure of the exact purpose of the "bias," but I know some people have lowered all the "max" values to limit intervention, and say it is better than just disabling. Try values of 30lb-ft or so. Then you can tune the table in specific areas if you want to get granular.

[Martijn]

I drove car today and played with the sparksmoothing setting, But without any result.
The car drives alot smoother when driving slow in 1th or 2th gear (10mlph or so) with spark smoothing on.
Bucking is almost complete gone. But there is a lot of bucking driving with steady speed in 4th and 5th gear with 1200 to 2000 rpm.

In the log file with the spark smoothing disabled, you can see that the spark advance is rock steady at 22 degree. But in the car you feel a lot of bucking.
In the other log file you can see that spark smoothing tries to adjust for the bucking by adjusting the spark advance. This helps a little but bucking is stil very noticeable.
Also attached the current tune, Does anybody has a idea to get rid of this bucking?

[92rsz]

The bucking is from reversion because of the cam. You won't be able to tune it all out with 17 degrees of overlap. The only thing that will get rid of it is a smaller cam

[Martijn]

I understand that I can not get rid of all of the bucking. But the bucking I experience now is quiet severe. So hopefully there is a way to smooth it out a bit to a acceptable level. For the rest of it Im very happy, The motor idles as a rock and runs like a beast. just a little bit less bucking part throttle in the higher gears between 1200 and 2000 rpm and I will be happy

[07GTS]

where u are solid 22 deg timing add more spark smoothing to that rpm/gear area in the low table, or try less timing so its lowers torque at that point, i find with mine sometimes being manual the timing if its solid value it causes a hesitation during steady speed driving so i adjust the smoothing so its only active enough to stop the jerkyness in steady driving

[Martijn]

Like you said, i only experience bucking at steady speed. so what should I do? lower timing even more in that area? and or increase smoothing (in that area)?
I tought 22 degree is allready pretty low, but I could alway try.

[07GTS]

yea just try the smoothing for that area increase or decrease see what works for it, for steady state the driving the smoothing will increase the sawtooth look in the timing the more its active so if ur solid 22 deg dosnt sound like any smoothing is being used there yet, but to much is just as bad as too little also got to find the sweet spot, or could even not be enough timing so try more/less see if that helps, sometimes u just got to see what your engine likes

[kingtal0n]

Did you try adjusting EOIT (Injector phase) to get rid of the bucking. This makes a huuuuuge difference on some cars.

As to steady spark advance.
1. It is never steady. You can't do 22.0000 perfectly every single event. IMO it is possible that This can start the oscillations because you get 21.995 21.853 22.054 22.135 up and down and each torque increase/decrease is magnified by the rate of the engine. Remember engine RPM can never be steady, the cylinder fires and the engine speeds up, and then peak and slows down while waiting for the next event, at low speeds and low output. A helpful way to smooth the engine out is to always increment the timing in a specific direction, for example 22.0 22.10 22.20 22.30 22.40 22.50, this way what you actually get is something like 21.95, 22.025, 22.055, 22.094, 22.105, 22.114, etc... The numbers gradually increase even though they are moving up and down with respect to the commanded target they always keep increasing and this is 'smoothing'

[kingtal0n]

These may help with your bucking problem the most
https://forum.hptuners.com/showthrea...l=1#post497476
https://forum.efilive.com/showthread...l=1#post202457
https://www.g8board.com/threads/tuni...er-cam.123306/



As to timing I recommend try something like this, I realized you have low resolution in the timing map. I didn't realize it was so awful. But anyways here I made you something which might help.