[RobZL1]

That's the table. See the "Minimum Final Spark" in the table heading?
There is the base and the long term tables. If you compare the top 3 rows with a stock 17 or 18 tune, you'll see it's much more positive in the older car. Then, if you look at a 2019, it's more negative than the 17/18. Then at some point they went even more poppy (22 maybe?), and made the top 3 rows still more negative- which is what is in your tune.

You could copy the top three rows from a 19 and see if you like it, then if it's still too much, copy the top three rows from a 17/18 (no pops at all).

To be "complete," you'd copy the top three rows in the long term table, too.

[2023_ZL1-AUTO]

Originally Posted by RobZL1

That's the table. See the "Minimum Final Spark" in the table heading?
There is the base and the long term tables. If you compare the top 3 rows with a stock 17 or 18 tune, you'll see it's much more positive in the older car. Then, if you look at a 2019, it's more negative than the 17/18. Then at some point they went even more poppy (22 maybe?), and made the top 3 rows still more negative- which is what is in your tune.

You could copy the top three rows from a 19 and see if you like it, then if it's still too much, copy the top three rows from a 17/18 (no pops at all).

To be "complete," you'd copy the top three rows in the long term table, too.

WOW I totally missed that !!! Thanks !!!

[2023_ZL1-AUTO]

OK, so this evening I re-flashed my final tune file from Andrew. Did so just to make sure something wasn't changed after the fact that I forgot about. I then drove around a bit, but the popping issue was identical to previous. So I did a test by just changing the ENGINE/Fuel/Cutoff DFCO, Disable ECT Hyst from 41F to 450F. I drove around a bit and on the decel there was noticeable improvement, almost zero popping. Maybe an occasional single pop once and a while if the decel was from slight a fast speed. But not the constant rumbling popping like before. It was slightly more noticeable when I was higher in RPMs and deceled. I then went back and change that value back to 41, then found a stock 2019 ZL1 tune file, replaced the top 3 rows on on ENGINE/Spark/Advance/Minimum Spark for both the Base and Long Term. Drove around a bit, but the problem was still pretty noticeable, at all RPMs. One thing to note, on all downshifts, either manual or auto, the popping and cracking was very noticeable no matter what changes I had made to the tune file.

[RobZL1]

Put the 17/18 values in there. It will all but go away completely.

[2023_ZL1-AUTO]

OK I'll track a 17/18 stock tune down. Sorry I missed the correct year!

Also here is a video of when I changed the ENGINE/Fuel/Cutoff DFCO, Disable ECT Hyst from 41F to 450F. You can hear one pop here and there but nothing like the day before.

https://youtube.com/shorts/lXOVBunb1fI?feature=share

Also, something weird that I ran into after flashing the computer yesterday, and changing either the final spark base/long term or the Cut-off DFCO temp. The modes of the car would change the exhaust NPP/valves. They stayed as the last mode they were in right before the flash. I know the modes were changing because I could tell by how the steering felt, like touring vs track. But the exhaust stayed open as I has just had it in track mode. I did find that after the first start up, when I turned off the car and restarted it seemed the modes went back to working correctly. Just a weird thing I noticed.

[2023_ZL1-AUTO]

OK, found a 2017 stock file from the HPTuners repos. Big value differences between the 2017 stock and 2023 stock/final tune file I have for both base and long term final spark. Obviously this table doesn't impact tuning at all, that makes sense. I'll make these changes later this evening and see what happens.

[RobZL1]

Originally Posted by 2023_ZL1-AUTO

OK, found a 2017 stock file from the HPTuners repos. Big value differences between the 2017 stock and 2023 stock/final tune file I have for both base and long term final spark. Obviously this table doesn't impact tuning at all, that makes sense. I'll make these changes later this evening and see what happens.

Yep. And notice it's just the top 3 rows (where decel occurs), and the rest of the table is the same. Most people's interpretation of this: they added crackles intentionally.

Regarding the modes after flashing- it will typically revert to Tour after a flash in my experience. May be different on newer OS's though.

[2023_ZL1-AUTO]

Originally Posted by RobZL1

Yep. And notice it's just the top 3 rows (where decel occurs), and the rest of the table is the same. Most people's interpretation of this: they added crackles intentionally.

Regarding the modes after flashing- it will typically revert to Tour after a flash in my experience. May be different on newer OS's though.

Gotcha! Andrews out for a bit, so I'll keep messing around until he gets back.

Also on the "...Regarding the modes after flashing- it will typically revert to Tour after a flash in my experience. May be different on newer OS's though."

What I was trying to say was that the mode changes to Touring, yes. But the NPP stayed in track / open NPP exhaust valve. and until I shut the car off and restarted, it didn't matter what mode I put the car in the Exhaust never changed in sequence with the mode selection. Just a weird issue. But after I shut off/restart, it acted normal.

[2023_ZL1-AUTO]

OK, copied the final spark top 3 rows from a 2017 "as found" file to replaced my final tune final spark top 3 rows. On the decel, there is almost no noticeable sounds from the exhaust. But, wow when I downshift, it makes the crazy loud snap, crackle and pop. I will wait till Andrew is back in town/at his shop and probably just turn the issue over to him. Here is a vid on the decel and the downshift:

https://www.youtube.com/shorts/oHXbwbNAgdY

[2023_ZL1-AUTO]

So another quick update/issue: So even after flashing ECM back to my final tune form Andrew the NPP valves are not operating correctly. When it starts up it's in the normal touring mode with NPP closed. But when I switch to Sport/Track the NPP valves open, but then when I switch back to Touring or Snow/Ice. They stay open, if I drive long enough they will just randomly close after decelerating or just hit the pedal quick and letting off. But, if i switch the gears to reverse, the NPPs close immediately and stay that way unless I'm in the Track/Sport mode.

[2023_ZL1-AUTO]

OK, I fixed the issue with the NPP valves!!!! I had a read file from after flashing my computer with the final tune file from Andrew, including the CCM module! So, I re-wrote that file to my ZL1s computer and selected "write entire" vs "write calibration". After that, my NPP valves are back working properly. Now, I still have to see if anyone knows the parameters that need changed to fix the stupid GM DFCO delay causing the snap, crackle and pop on decel and downshifting! I careless how much extra fuel I might use, I just HATE that "feature". I have a QX80 and it gets 13/18... I figured my ZL1 is doing a little better than that with all the mods !!!

[2023_ZL1-AUTO]

Kind of a big change or rather a switch out... I'm swapping out my Corsa Xtreme NPP Axle backs with the Stainless Works Legend series axle backs. I'm doing this because honestly, I never really got around to liking the way the Corsa Xtreme's sounded (other than when at WOT!) paired up with my CSP made by Stainless Works 2" long tube headers. My exhaust as is, just sounds to echoey, snappy and tinny for my liking. I've been assured and reassured by several ZL1 owners, they too changed from the Corsa Xtreme's (they had 2" long tubes as well), to the Stainless Works axle backs as well as other axle backs for a better and deeper sounding exhaust. So, I ordered this morning, they shipped today and since I'm in Columbus, they are scheduled to be delivered via FexEd tomorrow! Quick note, Justin at Stainless Works told me that for the next few days, their Stainless works axles backs are on sale and shipping is free. When I ordered this morning they have (4) in stock for immediate delivery ! I'll do my best, with my phone, to record a now vs after swap to show the difference !

[ZL1...SON]

Nice. I wish I could hear that legends system in person. I've been debating on replacing my stock suitcase for the legends.

[SOCAL.M6.ZLE]

Originally Posted by Schlok

Facts. It's an expensive hobby and the car is stupid fast from the factory anyway...but some of us like to have 'more.'

I agree, it is an expensive hobby no doubt... I spent about $79k for her new + dedicated transport from out of state (included a $3k mark up) :(

Pulled the motor at 1,500 miles, and have dumped $30,950 into the car with performance and cosmetic goodies... I feel blessed to have the cash to invest in this hobby, and a few years ago would have never expected to have a $110k, 900hp hobby car with only 3k miles!!!

My only disagreement, is that "these cars are stupid fast from the factory" I understand this is subjective, but for me personally... I felt the car to be sluggish, and was NOT impressed with the power level. After JRE's 125rwhp package, the car REALLY woke up, and i WISH thats how the car felt from the factory...

Cheers to modding fun!