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Who can tune my NPP with HPTuners?

 
Old 03-09-2019, 10:27 AM
  #1  
jimxms
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Default Who can tune my NPP with HPTuners?

Even with my Mild2Wild installed I still find that sometimes my NPP valves find a way to make my car sound crap. Ideally I'd like to get rid of my M2W setup and have the NPP tuned in HPTuners so that the following applies:

Eco - NPP closed all the time
Tour - NPP 25% open all the time
Sport & Track - NPP 100% open all the time

Does anyone know who can do this for me and how much it will cost?

Thanks
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Old 03-09-2019, 12:12 PM
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Bill Dearborn
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If you have an LT1 powered car you will have two sets of control valves in the exhaust. The AFM Exhaust Flow Control Valves which are ahead of the mufflers and the NPP Tail Pipe Exhaust Flow Valves which are after the muffler. If you have an LT4 powered car you will only have one set of valves in the exhaust, the NPP Tail Pipe Valves.

Both the AFM Valves and the NPP Tail Pipe Valves are controlled by the Chassis Control Module not the ECM so HP Tuners may not have access to program the module.

In an LT1 powered car if the engine is commanded to V4 operation the AFM valves and the NPP valves are closed. When the engine switches back to V8 mode the NPP valves open while the AFM valves have a designed in hysterisis (delayed opening).

Looking at the Chassis Control Module outputs it looks like the AFM valves can be controlled to positions between full open and full closed. However, the NPP valves are either open or closed.

Bill
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Old 03-09-2019, 12:35 PM
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Originally Posted by Bill Dearborn View Post
If you have an LT1 powered car you will have two sets of control valves in the exhaust. The AFM Exhaust Flow Control Valves which are ahead of the mufflers and the NPP Tail Pipe Exhaust Flow Valves which are after the muffler. If you have an LT4 powered car you will only have one set of valves in the exhaust, the NPP Tail Pipe Valves.

Both the AFM Valves and the NPP Tail Pipe Valves are controlled by the Chassis Control Module not the ECM so HP Tuners may not have access to program the module.

In an LT1 powered car if the engine is commanded to V4 operation the AFM valves and the NPP valves are closed. When the engine switches back to V8 mode the NPP valves open while the AFM valves have a designed in hysterisis (delayed opening).

Looking at the Chassis Control Module outputs it looks like the AFM valves can be controlled to positions between full open and full closed. However, the NPP valves are either open or closed.

Bill
Hi Bill, is that true for a 2014 M7 LT1 because I can't say that I've seen a second set of valves when under the car only the NPP's - unless of course they are tucked up behind the suspension?

If so, my engine doesn't have an 'eco' mode anymore really because I have a DOD delete on the engine. How is best to kill the AFM valves?
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Old 03-09-2019, 02:02 PM
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All LT1 powered cars have the valves in front of the mufflers. A number of track dogs running LT1 cars have had problems with the valve actuators failing due to high heat from all of the WOT operation seen on track.

Here is a for sale thread showing pictures of mufflers from a Grand Sport that of course has the LT1 engine.
https://www.corvetteforum.com/forums...post1598490383

Notice the valves located at the input to the mufflers.

Here is a sale thread showing pictures of Z06 mufflers:
https://www.corvetteforum.com/forums...post1595933196

Notice there are no valves ahead of the mufflers. When the C7 first went on sale in 2013 GM described the exhaust system and the valves ahead of the mufflers that were required to tune out the objectionable sound of the engine running in V4 mode. If you don't have the valves ahead of the mufflers somebody replaced the original mufflers with Z06 mufflers.

Bill
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Old 03-09-2019, 03:33 PM
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Originally Posted by Bill Dearborn View Post
All LT1 powered cars have the valves in front of the mufflers. A number of track dogs running LT1 cars have had problems with the valve actuators failing due to high heat from all of the WOT operation seen on track.

Here is a for sale thread showing pictures of mufflers from a Grand Sport that of course has the LT1 engine.
https://www.corvetteforum.com/forums...post1598490383

Notice the valves located at the input to the mufflers.

Here is a sale thread showing pictures of Z06 mufflers:
https://www.corvetteforum.com/forums...post1595933196

Notice there are no valves ahead of the mufflers. When the C7 first went on sale in 2013 GM described the exhaust system and the valves ahead of the mufflers that were required to tune out the objectionable sound of the engine running in V4 mode. If you don't have the valves ahead of the mufflers somebody replaced the original mufflers with Z06 mufflers.

Bill
Thanks for the links. The likelihood is that I just haven't noticed the AFM valves then. Is the esiest way to delete them, just pull a fuse and use HPTuners to blank the CEL's? I want these things gone!
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Old 03-09-2019, 04:20 PM
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Originally Posted by jimxms View Post
Thanks for the links. The likelihood is that I just haven't noticed the AFM valves then. Is the esiest way to delete them, just pull a fuse and use HPTuners to blank the CEL's? I want these things gone!
Here is one solution: https://www.corvetteforum.com/forums...post1592578029

No tune required.

If you disconnect the actuators from the control circuit and can blank the CELs there probably isn't any reason why you should pull the fuse as the valves will stay open all the time. But that requires a tune.

Bill
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Old 03-09-2019, 05:11 PM
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Originally Posted by Bill Dearborn View Post
If you have an LT1 powered car you will have two sets of control valves in the exhaust. The AFM Exhaust Flow Control Valves which are ahead of the mufflers and the NPP Tail Pipe Exhaust Flow Valves which are after the muffler. If you have an LT4 powered car you will only have one set of valves in the exhaust, the NPP Tail Pipe Valves.
This is mostly right however the 2015 Z06 shipped with AFM valves and NPP valves. They were later removed from future model years due to too many people causing them to fail at the track.

Originally Posted by jimxms View Post
Thanks for the links. The likelihood is that I just haven't noticed the AFM valves then. Is the esiest way to delete them, just pull a fuse and use HPTuners to blank the CEL's? I want these things gone!
Jim, regarding disabling the AFM valves the correct way, here, I wrote this a while back. It was in an older version of HPT but you should still be able to find your way around.

https://www.corvetteforum.com/forums...hp-tuners.html

Ant

Last edited by FYREANT; 03-09-2019 at 05:14 PM.
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Old 03-09-2019, 05:13 PM
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Originally Posted by FYREANT View Post
This is mostly right however the 2015 Z06 shipped with AFM valves and NPP valves. They were later removed from future model years due to too many people causing them to fail at the track.



Jim, regarding disabling the AFM valves the -correct- way, here, I wrote this a while back. It was in an onder version of HPT but you should still be able to find your way around.

Ant
Thanks man, I stumbled across your thread a short while ago and intend on giving it a try tomorrow.
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Old 03-11-2019, 11:11 AM
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Only the automatics have AFM valves (and NPP). Manuals only have NPP valves. There are 3 ways to keep the NPP valves open.

1.) Mild2Wild - Not really sure why you say your car sounds like crap with these, as essentially all they are doing is keeping your valves open 100% of the time when you have it enabled. Maybe they are not opening all the way or something -- could be an issue with your valves

2.) Pull fuse #42 - this keeps the valves open 100% of the time no matter what mode you're in. I'm assuming you don't want this.

3.) Tune them out with HPTuners as you suggested. - This is now an option luckily, however, costs an extra $100 is credits with HPT. So you need to pay $100 for regular credits on top of another $100 for credits to tune the CCM (Corvette Control Module - this is where the NPP settings reside). It's not hard to tune them out, just a few simple settings. But realize that doing this will ultimately void any warranty you may have on the car if you still have one. Some tuners are not familiar with tuning the CCM, as it sometimes requires your tune to be sent into HP Tuners for them to add it. But any tuner can take care of this for you. I'd say it'll probably cost you $300 in total or so ($200 in credits, $100 to the tuner) assuming all you're doing is tuning out NPP. IF you want to start tuning other things, obviously the money to the tuner will go up)

Last edited by djpelosi; 03-11-2019 at 11:12 AM.
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Old 03-11-2019, 12:18 PM
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Originally Posted by djpelosi View Post
Only the automatics have AFM valves (and NPP). Manuals only have NPP valves. There are 3 ways to keep the NPP valves open.

1.) Mild2Wild - Not really sure why you say your car sounds like crap with these, as essentially all they are doing is keeping your valves open 100% of the time when you have it enabled. Maybe they are not opening all the way or something -- could be an issue with your valves

2.) Pull fuse #42 - this keeps the valves open 100% of the time no matter what mode you're in. I'm assuming you don't want this.

3.) Tune them out with HPTuners as you suggested. - This is now an option luckily, however, costs an extra $100 is credits with HPT. So you need to pay $100 for regular credits on top of another $100 for credits to tune the CCM (Corvette Control Module - this is where the NPP settings reside). It's not hard to tune them out, just a few simple settings. But realize that doing this will ultimately void any warranty you may have on the car if you still have one. Some tuners are not familiar with tuning the CCM, as it sometimes requires your tune to be sent into HP Tuners for them to add it. But any tuner can take care of this for you. I'd say it'll probably cost you $300 in total or so ($200 in credits, $100 to the tuner) assuming all you're doing is tuning out NPP. IF you want to start tuning other things, obviously the money to the tuner will go up)
1. Mild2Wild only applies to NPP. If he sets the NPP to be fully open and his AFM valves are closings, it will sound awful.
2. Pulling fuses for NPP works to keep them open all the time. However pulling fuses for AFM will result in it throwing a code and generate a CEL. The NPP fuse does not generate a CEL, only the AFM valve fuse does.
3. Correct, will require extra credits to complete. I believe Jim has HPT himself and will not be paying a tuner to do it for him.

Ant
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Old 03-11-2019, 12:22 PM
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Originally Posted by FYREANT View Post
1. Mild2Wild only applies to NPP. If he sets the NPP to be fully open and his AFM valves are closings, it will sound awful.
2. Pulling fuses for NPP works to keep them open all the time. However pulling fuses for AFM will result in it throwing a code and generate a CEL. The NPP fuse does not generate a CEL, only the AFM valve fuse does.
Ant
The OP stated he has the M7, so he doesn't have AFM valves.
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Old 03-11-2019, 01:17 PM
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Originally Posted by djpelosi View Post
The OP stated he has the M7, so he doesn't have AFM valves.
The OP has a Stingray, not a Z06. ALL Stingray's have AFM valves, including the M7. I have an 2014 M7 myself in which I personally deleted the AFM valves on when I wrote the instructions for how to do it.

Last edited by FYREANT; 03-11-2019 at 01:17 PM.
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Old 03-11-2019, 02:26 PM
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Minor nitpick. CCM is chassis control module. Not Corvette Control Module. It also controls things like the oil and trans cooler fans, among other things. They're installed on more cars than just the Corvette.
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Old 03-11-2019, 03:03 PM
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Originally Posted by FYREANT View Post
1. Mild2Wild only applies to NPP. If he sets the NPP to be fully open and his AFM valves are closings, it will sound awful.
2. Pulling fuses for NPP works to keep them open all the time. However pulling fuses for AFM will result in it throwing a code and generate a CEL. The NPP fuse does not generate a CEL, only the AFM valve fuse does.
3. Correct, will require extra credits to complete. I believe Jim has HPT himself and will not be paying a tuner to do it for him.

Ant
Yep, until now I didn't realise I had AFM valves. So when I installed my M2W and the car continued to close what I assumed was the NPP valves (but was actually the AFM), I thought that the M2W wasn't working properly! But it obviously was, it was just the AFM valves closing instead! For information: a completely decatted long tube supercharged C7 with AFM valves closed, sounds and drives S**T! haha

So, I've pulled the AFM fuse, blanked out all of the CEL codes in HPTuners that FYREANT's thread listed, and now I'm hoping for some happier motoring

Thanks everyone

Last edited by jimxms; 03-11-2019 at 03:04 PM.
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Old 03-11-2019, 06:22 PM
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Originally Posted by jimxms View Post
Yep, until now I didn't realise I had AFM valves. So when I installed my M2W and the car continued to close what I assumed was the NPP valves (but was actually the AFM), I thought that the M2W wasn't working properly! But it obviously was, it was just the AFM valves closing instead! For information: a completely decatted long tube supercharged C7 with AFM valves closed, sounds and drives S**T! haha

So, I've pulled the AFM fuse, blanked out all of the CEL codes in HPTuners that FYREANT's thread listed, and now I'm hoping for some happier motoring

Thanks everyone
Hold on. So even if your not in ECO mode where AFM activities (as your M7).....the valves close?
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Old 03-13-2019, 08:37 PM
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Originally Posted by JT Corvette View Post
Hold on. So even if your not in ECO mode where AFM activities (as your M7).....the valves close?
After reading this thread I was wondering that myself.
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Old 03-14-2019, 02:53 AM
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Originally Posted by JT Corvette View Post
Hold on. So even if your not in ECO mode where AFM activities (as your M7).....the valves close?
Yep! And I think the reason is because my C7 is a Euro spec. Iíve been finding out the hard way that a lot of the programming is different. For example, my car always starts in ECO no matter what mode it was left in before. As I understand it, the US models start in the last mode unless the last mode was Track? Is that right?
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Old 03-14-2019, 02:20 PM
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Originally Posted by JT Corvette View Post
Hold on. So even if your not in ECO mode where AFM activities (as your M7).....the valves close?
With the M7 cars AFM only activates when in ECO Mode. With the A8 AFM activates in all modes unless the transmission is put in Manual Mode.

Bill
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Old Yesterday, 01:01 PM
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The M7 closes the NPP valves in ANY mode once you're in 4th gear and higher. However, the AFM valves do not close unless you are in ECO mode and V4 kicks in. Tuning the CCM changes the way the NPP valves work, not the AFM valves. You can tune the AFM valves out by tuning the ECU, not the CCM.
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Old Yesterday, 01:33 PM
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Originally Posted by TriPinTaZ View Post
The M7 closes the NPP valves in ANY mode once you're in 4th gear and higher. However, the AFM valves do not close unless you are in ECO mode and V4 kicks in. Tuning the CCM changes the way the NPP valves work, not the AFM valves. You can tune the AFM valves out by tuning the ECU, not the CCM.
Iím sorry, youíre incorrect. You have it backwards. The AFM valves require access to the C304 module (CCM) and two credits to get into it. The NPP is what you can tune in the ECM, not the AFM.
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