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NPP fuse

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Old 07-18-2018, 12:02 PM
  #41  
Bill Dearborn
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Originally Posted by thompstl1 View Post
Bill,
My 2018 Z06 A8 will switch into V4 mode even if I've got the dial set to Sport. I've watched it do this quite a number of times. Won't get into the exhaust valve discussion as I think pictures (while driving) or some type of tattle tale on the actuator valves will be the only sure way to settle this discussion.
Sorry, I thought somebody said it wouldn't switch in Sport Mode. It seems like there is a lot of mixing of terms. If the transmission needs to be in manual to keep the engine from switching to V4 mode then the trial should be done that. Set engine sound management to Track, Select Transmission Manual mode and drive around like somebody with an M7 and see if the valves close. If you can verify they close then maybe there is a difference between M7s and A8s. I doubt it since the FSM would have indicated that but maybe it was overlooked.

I can try and use the PDR to record the sound made while driving my car in Eco and then Tour on a slight upgrade at 50 mph in cruise in 6th gear.

Bill
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Old 07-18-2018, 12:25 PM
  #42  
Thomasmoto
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My car isn't stock, 2016 Z06. When we changed the cam we lost the CD ability, but even when sound management set to track my valves will close at lower speeds or lower power levels. So I have pulled the fuse. It's the only way to guarantee the valves remain open 100% of the time, which is how I like it.
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Old 07-18-2018, 12:35 PM
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Originally Posted by Bill Dearborn View Post
Sorry, I thought somebody said it wouldn't switch in Sport Mode. It seems like there is a lot of mixing of terms. If the transmission needs to be in manual to keep the engine from switching to V4 mode then the trial should be done that. Set engine sound management to Track, Select Transmission Manual mode and drive around like somebody with an M7 and see if the valves close. If you can verify they close then maybe there is a difference between M7s and A8s. I doubt it since the FSM would have indicated that but maybe it was overlooked.

I can try and use the PDR to record the sound made while driving my car in Eco and then Tour on a slight upgrade at 50 mph in cruise in 6th gear.

Bill

Bill, I can tell you this since my first C7 Z06 was a 2015 Z06 M7.There is a big difference in how the car lets you use the accel pedal much more than the A8's do. The A8's won't rev up high like the M7's will. And it's a big enough difference to be able to tell just by driving. So having a difference in how the NPP works wouldn't surprise me one bit. But I know for 100% certain that pulling the fuse/MTW switch, is the only way my car will keep the valves open 100% of the time.
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Old 07-18-2018, 12:41 PM
  #44  
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Originally Posted by Bill Dearborn View Post
Sorry, I thought somebody said it wouldn't switch in Sport Mode. It seems like there is a lot of mixing of terms.
Bill
Yup, both with what happens between the two kinds of "track" modes (one on the rotary dial on the center console, and the other on the touch screen), and the differences between the M7 and A8. The "sound management" function on the touch screen changes nothing but the flow path through the mufflers.

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Old 07-19-2018, 12:10 AM
  #45  
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Originally Posted by Thomasmoto View Post
My car isn't stock, 2016 Z06. When we changed the cam we lost the CD ability, but even when sound management set to track my valves will close at lower speeds or lower power levels. So I have pulled the fuse. It's the only way to guarantee the valves remain open 100% of the time, which is how I like it.
You may have lost the AFM activity with the engine but I have been reading in the Service Manual and although it isn't clearly stated it looks like the Chassis Control Module (not the ECM) initiates the start and stop of V4 operation by sending signals to the ECM. I was also reading how the Range AFM Module works and they indicate the module disrupts the signal to the ECM telling it to initiate V4 mode. The Chassis Control Module is connected to the ECM through a data bus plus directly controls the muffler valves and it is likely that it gives a command to both the engine and the mufflers but only the mufflers receive it. The only way to know is with a completely stock A8. Supposedly the A8 doesn't implement V4 when it is set in manual mode. Set Engine Sound Management into Track Mode, Run manual shift mode with ride control set in Tour and see if the exhaust changes. Then do the same thing again with the transmission in auto shift mode in Tour and see if the exhaust noise changes with V4 operation. That can be done by setting the instrument cluster display to info and whatever screen shows V4/V8 operation in the center of the tach/speedo.

Bill

Last edited by Bill Dearborn; 07-19-2018 at 12:16 AM.
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