NPP valves/drinving modes not working correctly after flash...

[2023_ZL1-AUTO]

So, I've had an issue with my exhaust doing the snap/crackle and pop, on my 2023 ZL1 A10 when deceleration or the transmission downshifting (wither manually or automatically). It happens every time I lift off the pedal after getting into the throttle, doesn't need to be WOT, or when the trans downshifts either manually or automatically when at a higher RPM like 4000+. This is a video example with the car in track mode of what I'm referring too: https://www.youtube.com/shorts/ojV7wf6t7l4

Several users on Camaro6 suggested to me that I could try and replace the top 3 rows of my base and long term final spark tables in my final tune file, with the top 3 rows from a stock 2017/2018 (got from HPtuners repository) and see if it helps. Well, I did and it did help but not fully. I also turned off DFCO completely (I think) by changing the ENGINE/Fuel/Cutoff DFCO, Disable ECT Hyst from 41F (stock value) to 450F. I think after, I might of only heard one 1 insignificant pop, but no snap, crackle and pop. However, after doing that flash, I noticed my NPP valves wouldn't close properly when switching between modes to touring or snow/ice. Even after flashing the ECM back to my final tune file, the NPP valves still don't operate correctly. When it starts up it's in the normal touring mode with NPP closed. But when I switch to Sport or Track mode, the NPP valves open but stay open even when I switch back to Touring or Snow/Ice. If they are closed in touring and I hit the throttle hard, they open like they should. But they don't close again when I'm back driving normal. Sometimes I noticed that randomly, if I drive around long enough, they will just close on their own (obviously I am in touring mode) But, every time they are "stuck open" and I'm in touring or S/I mode and I put the car in to reverse, the NPPs close immediately and stay that way until they are opened again. Attached are the photos of the base final spark time so yo use what I'm referring too. Any ideas on correcting this issue would be appreciated. Thanks


2017_stock_base.JPG2023_stock_and_final_tune_file_base.JPG

[2023_ZL1-AUTO]

OK I fixed the issue with the NPP valves not operating correcting. I had a read file form after I flash with my final tune file that included the CCM module. I re-wrote that file to the computer but selected "write entire" vs "calibration". After that was completed, the NPP valves work properly.

As for the rumbling or the snap, crackle and pop goes it's still there and note that I have the Enable rumble turned off on all 4 modes. But I think this is for start up only so I don't see how it would effect operational mode as far as deceleration and or downshifting.

[TriPinTaZ]

There is a bit more to crackles than just changing minimum spark. Also, the main spark table doesn't affect off throttle timing so changing that wont help. The main table can be used if you want to use the gas pedal to kick the car in and out of DFCO mode to make some bangs. Even with a stock main spark table and putting say -5 in the minimum table, you can just barely touch the gas pedal to kick it in and out of DFCO to get some crackles.

High ethanol content, 103MM TB's and some aftermarket intakes add to the difficulty in making crackles.

[2023_ZL1-AUTO]

There is a bit more to crackles than just changing minimum spark. Also, the main spark table doesn't affect off throttle timing so changing that wont help. The main table can be used if you want to use the gas pedal to kick the car in and out of DFCO mode to make some bangs. Even with a stock main spark table and putting say -5 in the minimum table, you can just barely touch the gas pedal to kick it in and out of DFCO to get some crackles.

High ethanol content, 103MM TB's and some aftermarket intakes add to the difficulty in making crackles.

Thanks Tri ! It's crazy that it's made to work that way from GM, I just want it GONE !!! (HEHE) https://www.youtube.com/shorts/ojV7wf6t7l4

It's actually really loud, and I mean in a very annoying way. But, that might be due to the Corsa Xtrem mufflers too, so maybe it's time to look at difference mufflers as part of the solution as well.

[ZLRob]

Mufflers don't help your situation at all. Rumble mode is only meant to affect initial starting and DFCO is the area you want to look into. The minimum spark tables as well. I may be leaving something else off the table here, but I think the majority of the bases have been covered as far as areas to check.

Unfortunately GM made cracking and popping in the factory tune a thing. I remember driving a 22 LT1 back in 21.. It crackled and popped like crazy, I wasn't mad at it, but it definitely made the drive a little interesting needless to say.

[C7vette2014]

Theres a guy on youtube who shows how to do a crackle tune on his C7 corvette (gen 5). You have to adjust the VTTables to trick the engine to pull timing in those decel areas. Look up his video and maybe do the opposite to fix your crackles.

[TriPinTaZ]

Thanks Tri ! It's crazy that it's made to work that way from GM, I just want it GONE !!! (HEHE) https://www.youtube.com/shorts/ojV7wf6t7l4

It's actually really loud, and I mean in a very annoying way. But, that might be due to the Corsa Xtrem mufflers too, so maybe it's time to look at difference mufflers as part of the solution as well.

Ah I didn't realize you wanted them gone. I think they sound amazing. There is a way to make them go away but since I like crackles, I'm not telling hahahaha. email me your file and I'll make a simple change that usually works.

[will_974]

My understanding is there is a 'DFCO Active Timer' that causes this.
On the SS Camaro, It is pretty much zero'd out, so the DFCO starts as soon as other enable conditions are met
VCM suite does not have this paramenter.

I have located it on a 2021 Zl1, it should not be much different on the 2023 ZL1.
PM me if other methods do not work, I can locate and adjust this paramenter for you to give you the desired result.