Exhaust issues....NPP won't close
#1
Burning Brakes
Thread Starter
Exhaust issues....NPP won't close
I've had some exhaust issues lately. Recently, when in sport mode changing over to tour mode exhaust is not get quieter like it did in the past. I went into the engine mode and set it to stealth with no luck. Even on start up and tour mode with stealth setting the butterflies are awayS open. Wtf?
I've also noticed them upon hard acceleration the car does not have an angry scream as it used to as well. Something is definitely up I checked the fuses they are both not blown. Car is in stealth engine management and mode is in Tour, start up and both valves are open. Maybe software issues???
I've also noticed them upon hard acceleration the car does not have an angry scream as it used to as well. Something is definitely up I checked the fuses they are both not blown. Car is in stealth engine management and mode is in Tour, start up and both valves are open. Maybe software issues???
Last edited by chasboland; 09-27-2016 at 08:46 PM. Reason: Updated info
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Ron_Attleboro_MA (06-12-2018)
#2
Melting Slicks
Member Since: Aug 2016
Location: MOUNTAIN HOME Arkansas
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That sounds strange. When I am at idle (like in garage where it's quiet) or cruising & change the exhaust mode it immediately gets quieter or louder. There are electrical plugs on the outside exhaust pipes at each. Don't suppose they could have come loose (locking clips) or gotten so wet they are not working properly to allow changes. Seems you would maybe have gotten a code too. I am just totally guessing, I'm sure someone will come up with the correct answer. Really don't get why W.O.T. doesn't sound same, maybe you're just aggravated with the modes & "suspect" the engine sounds different. Sorry, I should have just waited for an expert!--HA!
#3
Burning Brakes
Thread Starter
That sounds strange. When I am at idle (like in garage where it's quiet) or cruising & change the exhaust mode it immediately gets quieter or louder. There are electrical plugs on the outside exhaust pipes at each. Don't suppose they could have come loose (locking clips) or gotten so wet they are not working properly to allow changes. Seems you would maybe have gotten a code too. I am just totally guessing, I'm sure someone will come up with the correct answer. Really don't get why W.O.T. doesn't sound same, maybe you're just aggravated with the modes & "suspect" the engine sounds different. Sorry, I should have just waited for an expert!--HA!
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z51vett (09-27-2016)
#6
I don't know if the Z06's work differently than the ZR1's, but the valves in my ZR1 stopped working and the solenoid that controls them needed to be replaced. Wasn't a big deal. Pretty cheap part and easy to replace.
#8
Maybe somebody pulled the fuse as a prank??! Did you check the fuse box?
#10
Le Mans Master
Can you check to see if it's one or both sides? That might be tough, but if you check and find out that only one of the valves is stuck open, then that's probably your answer, one of the valves got cooked or failed.
Point being one side stuck open probably sounds almost exactly like both sides.
If both are actually doing it then it's going to be a control logic thing. You could try pulling the battery for a "hard reset". If that doesn't help, you're stuck with the dealer.
Point being one side stuck open probably sounds almost exactly like both sides.
If both are actually doing it then it's going to be a control logic thing. You could try pulling the battery for a "hard reset". If that doesn't help, you're stuck with the dealer.
Last edited by davepl; 09-28-2016 at 01:11 PM.
#11
Burning Brakes
Thread Starter
Can you check to see if it's one or both sides? That might be tough, but if you check and find out that only one of the valves is stuck open, then that's probably your answer, one of the valves got cooked or failed.
Point being one side stuck open probably sounds almost exactly like both sides.
If both are actually doing it then it's going to be a control logic thing. You could try pulling the battery for a "hard reset". If that doesn't help, you're stuck with the dealer.
Point being one side stuck open probably sounds almost exactly like both sides.
If both are actually doing it then it's going to be a control logic thing. You could try pulling the battery for a "hard reset". If that doesn't help, you're stuck with the dealer.
Last edited by chasboland; 09-28-2016 at 05:53 PM.
#13
Heel & Toe
NPP won't close
I've had some exhaust issues lately. Recently, when in sport mode changing over to tour mode exhaust is not get quieter like it did in the past. I went into the engine mode and set it to stealth with no luck. Even on start up and tour mode with stealth setting the butterflies are awayS open. Wtf?
I've also noticed them upon hard acceleration the car does not have an angry scream as it used to as well. Something is definitely up I checked the fuses they are both not blown. Car is in stealth engine management and mode is in Tour, start up and both valves are open. Maybe software issues???
I've also noticed them upon hard acceleration the car does not have an angry scream as it used to as well. Something is definitely up I checked the fuses they are both not blown. Car is in stealth engine management and mode is in Tour, start up and both valves are open. Maybe software issues???
#14
Burning Brakes
Thread Starter
I had this issue with my 2013 GS. There is a vacuum canister somewhere in the back that cracked open and therefore no vacuum to actuate the solenoids that actuate the valves (opening and closing). It happened a second time (after replacing the canister) and it was due the hose getting dried up from all the heat generated by the exhaust. Check your vacuum canister and your hoses.
#15
Drifting
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chasboland (10-02-2016)
#17
Turn 12!
https://www.corvetteforum.com/forums...rack-mode.html
#19
Burning Brakes
npp exhaust valve not working
2017 GrandSport, I have one npp exhaust valve that never closes, drivers side. Tour mode, the right closes but not the left. Track mode, the right opens, and the left is already open. I guess I will schedule a service appointment. I hope it is just the electronic valve control and not something more serious, harder to find the cause. I am looking to see if anyone else has had a valve controller go?
#20
Team Owner
I had this issue with my 2013 GS. There is a vacuum canister somewhere in the back that cracked open and therefore no vacuum to actuate the solenoids that actuate the valves (opening and closing). It happened a second time (after replacing the canister) and it was due the hose getting dried up from all the heat generated by the exhaust. Check your vacuum canister and your hoses.