Spark for Decel

[HPLouis]

I'm going through my tune and I noticed that my tuner changed this and raised the values:

Spark for Decel
Tuned
RPM/TEMP 600 900 1400 1900 2400 2900 3400
160 36.000 36.000 36.000 36.000 36.000 36.000 36.000
120 36.000 36.000 36.000 36.000 36.000 36.000 36.000
80 36.000 36.000 36.000 36.000 36.000 36.000 36.000
40 36.000 36.000 36.000 36.000 36.000 36.000 36.000
0 36.000 36.000 36.000 36.000 36.000 36.000 36.000

Stock
RPM/TEMP 600 900 1400 1900 2400 2900 3400
160 20.000 11.000 8.000 10.000 15.000 20.000 30.000
120 20.000 11.000 8.000 10.000 15.000 20.000 30.000
80 20.000 11.000 8.000 10.000 15.000 20.000 30.000
40 20.000 14.000 14.000 10.000 15.000 20.000 30.000
0 20.000 15.000 20.000 20.000 25.000 25.000 30.000

I figured that this would be the spark that is commanded when I'm off the throttle and decelerating. I did some reading and I see that people lower the values when they want to hear popping in the exhaust upon deceleration. I changed it back to stock and I didn't get the popping so I'm trying to figure out why this would be raised and also changed to all the same number. I want to make sure it's ok because the tune was aggressive so I've been fixing it (i.e. total timing was 23 at WOT and there was no decrease for intake air temps until 176 degrees). I can't get the tuner so I have to ask here.

Thanks

 

[01yellercobra]

The popping (crackle tune) is a mix of timing and fuel. It's not just one or the other. I set my son's up a little aggressive and he had flames shooting on decel. Oops.

Are those numbers actual degrees of timing or are they adders of some sort? He might have done it to smooth out the car when lifting off the throttle.

 

[HPLouis]

Hi,
They're actual numbers.

You've got a good point there. Let me go for another drive and see how it feels when I lift off the throttle between the 2 tunes.

 

[HPLouis]

I just want to make sure that the spark is not too high. I didn't hear any detonation but I didn't hear any detonation at 23 degrees of timing and the IAT at 148 degrees.

I want to be as safe as possible with this tune.

By the way, it's for the 04 Cobra, not the other two.

 

[03cobra#694]

What fuel?

 

[13COBRA]

The popping (crackle tune) is a mix of timing and fuel. It's not just one or the other. I set my son's up a little aggressive and he had flames shooting on decel. Oops.

Are those numbers actual degrees of timing or are they adders of some sort? He might have done it to smooth out the car when lifting off the throttle.

Like this?

 

[01yellercobra]

Look at the spark source when you're in decel. I'm assuming it should be reading off that table you listed.

The engine isn't under any real load in decel so you shouldn't have to worry about knocking at that point.

 

[01yellercobra]

Like this?

View attachment 1813732

Lol. Not quite that aggressive. That pic is poster worthy.

 

[13COBRA]

Lol. Not quite that aggressive. That pic is poster worthy.

It's coming... haha I'm going to have the guy put up the lap time, date, etc on it then I'll get it printed.

 

[HPLouis]

Look at the spark source when you're in decel. I'm assuming it should be reading off that table you listed.

The engine isn't under any real load in decel so you shouldn't have to worry about knocking at that point.

Oh, ok. I'll leave it alone.

And, you're right, in the datalog, the spark source is that table.

 

[03cobra#2]

Your tuner probably raised spark in the low load areas to prevent exaust popping during decel. Usually you will see mid 20's to lower 40's. Drive it and see how it does.

I'm currently experimenting with the same thing in my tune.