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Old 07-14-2014, 08:51 PM
  #41  
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Originally Posted by Klyde
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I have read that article in its entirety many weeks ago. Also last month when I went over 500miles break-in I pulled the fuse on my C7. Unfortunately I have an automatic. Went for a spin after popping the fuse and was rewarded with a low speed drone whenever I held a constant speed. The auto just hits the wrong RPM’s at the wrong time. When I got onto the highway my car went right intoV4 mode and it sounded terrible. Turned around and headed home and in my neighborhood, while in Sports Mode doing 35 mph it kicked into V4 mode again and at that moment I decided to put the fuse back in.

Before my first post AFVETTE mentioned AFM and asked about tuning it out. Millpond stated that for an auto just use Sport or Track to illiminate AFM. MKR1966 got it right by saying with auto your screwed. I looked up the OP’s stats and he shows a 2009 as his vette so I didn’t know if he has an auto or a manual and he doesn’t mention the menu so I didn’t know his level of use with the C7. So in my first post I mentioned turning NPP off in the menu but go on to mention that you still have AFM and its two valves to deal with based on my earlier experience. I explain that, with an auto, AFM is active in any mode and do to its function cannot be removed without re-tuning which voids your warranty. Later Theta, a tech contributor, made the statement that the AFM valves were for sound control which I knew to be false because of statements made by GM engineers. At no point did I ever state that removing the fuse would not deactivate the NPP system. My statement was it is not necessary to do so. Actually it is quite annoying if you have an automatic like I do and works a whole lot better leaving it in and turning it off in the menu. My statement to Theta about being careful with promoting this as a solution was because there are many different technical levels of people on this forum and some may not fully understand what he is suggesting. He took this as an insult which it was not meant to be but to each his own.

After removing the fuse weeks ago I can only think that you who swear by it must certainly have manual transmissions. I could not tolerate it for more than the ten minutes it was pulled. As Theta states “What’s bad for one man is blessed for another”. My thoughts are there is no need to pull that fuse.
One, you can leave my name out of your disparaging statements, and two, you can quote me directly or not at all.

I'm really sick of dealing with you and your misinformation and flip-flops at this point. If you still truly believe that pulling Fuse #41 causes any harm, damage, or other issue with the car, I can't possibly begin to help you...

The primary function of the AFM valves is the attenuation of exhaust gases and pulses. Your tone throughout this entire thread has been negative, and you attacked me first. You dragged us all into an AFM debate, which was not the original point at all.

Last edited by Theta; 07-14-2014 at 08:55 PM.
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Old 07-14-2014, 08:58 PM
  #42  
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Originally Posted by Theta
freebird, if you're still reading this post, I will quickly break this down for you.

As you specifically labeled your post NPP, I will assume that you are concerned with only the NPP valves. The AFM valves (as others have been worried about here) were not part of your original question, and the options for removing the AFM feature are very straightforward.

To answer your question fully, though, without making you read through an additional 10 pages of information, the NPP valves are controlled by the CCM. This module attenuates the electronic valves based on selection criteria (the first being the ESM selector).

There are two caveats to the operation of the NPP valves in the 'OFF' state - the most important one here that is (apparently) being argued over is the FACT that the system has a tip-in based on TPS that actually does close the valves to a certain degree below a specific RPM. In most reported cases, the tip-in point is 1700rpm.

So, as you can see, even when the system is "off", it's not truly off. To permanently disable the electronic (unlike the C6's vacuum-controlled) valves from closing, the simple removal of Fuse 41 from the front engine compartment will do the job with no risk involved (contrary to the other misinformation you may have seen here). There is no error reported to the system, as these valves serve only to attenuate sound, and are not actively monitored for position. If the valves are removed, that's a bit of a different story, but that's an entirely different topic (that we do have a few threads about if you're so inclined).

Again, everyone lost sight of the actual question, and jumped straight to conclusions. This, however, was the information that the OP was looking for. Otherwise, he'd be asking about AFM, and not NPP.
Got it. You understood my question. Thanks very much. I will pull the fuse. Appreciate the help!!
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Old 07-14-2014, 08:59 PM
  #43  
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Originally Posted by freebird
Got it. You understood my question. Thanks very much. I will pull the fuse. Appreciate the help!!
Thank you for posting that, freebird. I appreciate knowing that I answered the question you were actually asking.
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Old 07-14-2014, 09:03 PM
  #44  
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Theta:
Talk about putting words in ones mouth. I've never said that pulling fuse 41 will harm your car. I said removing AFM could possibly. That's why it voids your warranty. Do you actually read what I have said or do you just want only your view? I'm an electronic technician and I've been through the diagram you have posted and I see nothing harmful with removing that fuse. Well except for how bad it sounds when it kicks into V4 mode which with an automatic I have no control over.
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Old 07-14-2014, 09:04 PM
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Originally Posted by thebiglittledog
I had the mild to wild in my 13 GS had it on the wild mode 99% of the time, love the drone if thats what you call a bad *** sound of the Corvette, So when I picked up my C7 and after reading many threads posted on this subject as Theta has stated I pulled my fuse 41 and and love every minute of the drone, also when I pull up to light all the other cars around seam to like the drone as I have had many many many people ask me to rev her up so they can here the DRONE, Theta thanks for all your onsite to your knowledge of the working of the C7. Klyde it may be a sad day but you were wrong on this.
Exactly how I feel. Love the DRONE. I bought a manual, so the downshifts will be nice.
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Old 07-14-2014, 09:05 PM
  #46  
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Originally Posted by Klyde
Theta:
Talk about putting words in ones mouth. I've never said that pulling fuse 41 will harm your car. I said removing AFM could possibly. That's why it voids your warranty. Do you actually read what I have said or do you just want only your view? I'm an electronic technician and I've been through the diagram you have posted and I see nothing harmful with removing that fuse. Well except for how bad it sounds when it kicks into V4 mode which with an automatic I have no control over.
Klyde, I've sent you a PM - please read it.

My only problem here is that you've publicly accused me of spreading potentially dangerous information. That needs to stop, unless you can point me to a direct example in which this is the case.

Your words are damaging more than you realize, which has caused me to take offense. I've never been concerned with the topic of AFM, as you see by my extended final answer to the OP, which was accepted above.
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Old 07-14-2014, 09:15 PM
  #47  
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Now that the OP's seen the answer, I'm going to set the record straight on the AFM quote / video that Klyde was talking about.

The AFM exhaust valves (right before the muffler) are not to be confused with the AFM exhaust valves (at the lifters in the block). Same name - different area and function. Odd, right? This may be the source of some confusion regarding the video you watched and any information you've read about AFM. The exhaust valves at the mufflers are rarely talked about, but I swear/promise/guarantee the following is true:

The rear AFM acoustic modulation valves (which is what they're actually specified as) are designed to modulate the exhaust gas pulses to give a more pleasing tone to the ear - in layman's terms - it sounds like crap with those wide open in 4-cylinder mode.

Klyde, if this is the source of the disagreement, it's a simple misunderstanding. I'm willing to let bygones be bygones and end the mini-feud here. It's just hurtful (and as I said, damaging) to infer that any advice given here (which was merely the answer of removing a fuse) is/was something that could potentially cause harm to another user's vehicle... Hopefully you understand.

Full text here of the initial GM release:

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the cylinder deactivation system ON to deactivate engine cylinders 1, 7, 6, and 4, switching to a V4 mode. The engine will operate on 8 cylinders, or V8 mode, during engine starting, engine idling, and medium to heavy throttle applications.

When cylinder deactivation is commanded, the ECM will determine what cylinder is firing and begin deactivation on the next closest deactivated cylinder in firing order sequence. For example, if cylinder number 1 is on its combustion event when cylinder deactivation is commanded ON, the next cylinder in the firing order sequence that can be deactivated is cylinder number 7. If cylinder number 5 is on its combustion event when cylinder deactivation is commanded ON, then the next cylinder in the firing order sequence that can be deactivated is cylinder number 4.

Cylinder deactivation is accomplished by not allowing the intake and exhaust valves to open on the selected cylinders by using special valve lifters. The deactivation lifters contain spring loaded locking pins that connect the internal pin housing of the lifter to the outer housing.

The pin housing contains the lifter plunger and pushrod seat which interfaces with the pushrod. The outer housing contacts the camshaft lobe through a roller. During V8 mode, when all cylinders are active, the locking pins are pushed outward by spring force, locking the pin housing and outer housing together causing the lifter to function as a normal lifter. When cylinder deactivation is commanded ON, the locking pins are pushed inward with engine oil pressure directed from the valve lifter oil manifold (VLOM) assembly solenoids. When the lifter pin housing is unlocked from the outer housing, the pin housing will remain stationary, while the outer housing will move with the profile of the camshaft lobe, which results in the valve remaining closed. One VLOM solenoid controls both the intake and exhaust valves for each deactivating cylinder. There are 2 distinct oil passages going to each cylinder deactivation lifter bore, one for the hydraulic lash-adjusting feature of the lifter, and one for controlling the locking pins used for cylinder deactivation.

Although both intake and exhaust valve lifters are controlled by the same solenoid in the VLOM, the intake and exhaust valves do not become deactivated at the same time. Cylinder deactivation is timed so that the cylinder is on an intake event. During an intake event, the intake cam lobe is pushing the valve lifter upwards to open the intake valve against the force of the valve spring. The force exerted by the valve spring is acting on the side of the lifter locking pins, preventing them from moving until the intake valve has closed. When the intake valve lifter reaches the base circle of the camshaft lobe, the valve spring force is reduced, allowing the locking pins to move, deactivating the intake valve. However, when cylinder deactivation is commanded ON, the exhaust valve for the deactivated cylinder is in the closed position, allowing the locking pins on the valve lifter to move immediately, and deactivate the exhaust valve.

By deactivating the exhaust valve first, this allows the capture of a burnt air/fuel charge, or exhaust gas charge, in the combustion chamber. The capture of exhaust gases in the combustion chamber will contribute to a reduction in oil consumption, noise and vibration levels, and exhaust emissions when operating in V4 mode cylinder deactivation mode.

During the transition from V8 to V4 mode, the fuel injectors will be turned OFF on the deactivated cylinders. To help prevent spark plug fouling, the ignition system secondary voltage or spark is still present across the spark plug electrodes on the deactivated cylinders. If all enabling conditions are met and maintained for cylinder deactivation operation, the ECM calibrations will limit cylinder deactivation to a cycle time of 10 minutes in V4 mode, then return to V8 mode for 1 minute.

Switching between V8 and V4 modes is accomplished in less than 250 milliseconds, making the transitions seamless and transparent to the vehicle operator. The 250 milliseconds includes the time for the ECM to sequence the transitions, the response time for the VLOM solenoids to energize, and the time for the valve lifters to deactivate, all within 2 revolutions of the engine crankshaft.

Last edited by Theta; 07-14-2014 at 09:23 PM.
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Old 07-14-2014, 10:16 PM
  #48  
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In going back and reading several of the replies from today, I want to thank many of you for the support and kind words. It's difficult to do this job (as it is for the moderators and admins), especially when you get dozens of requests and PMs per day. Arguing facts becomes a tiresome (and rather bothersome) process that takes away time from my family and others that need help here on the boards. It pays to remember that at times.

To all that have been discussing the possibility or viability of a switched system, it is, indeed, doable, as I have it set up on my own car. Initially, I wanted to make it wireless, but that wasn't the most reliable implementation.

Unfortunately, the Mild2Wild will not work with the C7, even with a fuse size change - this has been confirmed by the creators of the M2W.

I would encourage everyone here looking at doing a 'switch-type' mod on Fuse 41 to view the previously-mentioned thread:

http://forums.corvetteforum.com/c7-t...ck-result.html

We went through quite a bit of discussion and research before settling on a wired design. It really comes down to where you'd like to put the switch. Some are putting it in the engine bay (or directly on the fusebox cover), while others like myself are wiring it into the cabin via the 'clutch-grommet'.
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Old 07-14-2014, 10:17 PM
  #49  
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First of all I am not trying to fight with you. The comment I made about damaging the engine was in reference to removing the AFM exhaust valves. Under V4 mode this could have bad effects. At no time did I state that what you suggested was harmful. It is probably the most direct way to inhibit the NPP system with little or no harmful effects. The only thing I can think of would be the valves never cycling and over time they may freeze up but, maybe not. Having an automatic, it is my opinion that removing that fuse is not necessary. That is my opinion. Which is just that, My Opinion. My purpose was not to attack you but to make everyone aware that there are some problems with the deactivation of NPP and V4 mode. Those with manuals can just never use Eco mode and that’s that. Those of us with automatics have to contend with the V4 sound because there is no mode that it doesn’t activate. My C7 will go into V4 mode at 35 mph in any mode and without NPP it sounds bad. That is the reasoning behind my statement that it is not necessary to remove that fuse. All I can think is that those who like it must not have auto’s. Anyone can pull that fuse and not worry about any harm. I’d recommend everyone to do so and make their own choice. Theta did an excellent job at coming up with the least harmful way of deactivating NPP in a way that is so simple anyone of us can try it. Him and several other members have test this method for months with no negative results. I my self have tried it and decided its not for me.

The reason for the AFM discussion was several members brought it up with some questions and if you have an automatic it is a major factor and consideration in NPP deactivation. The OP never stated which trans he has so it became part of this discussion. I believe the misunderstanding between Theta and I comes from us owning two very different vehicles. Unfortunately deactivation doesn't bode well with automatics.

I apologize to all who think I was attacking Theta. I am a technical person by nature and career and sometimes come across to directly. My focus was not to attack but to bring forward the problems with AFM associated with NPP so that every member especially those with automatics could make an informed choice.
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Old 07-14-2014, 10:23 PM
  #50  
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Originally Posted by Klyde
First of all I am not trying to fight with you. The comment I made about damaging the engine was in reference to removing the AFM exhaust valves. Under V4 mode this could have bad effects. At no time did I state that what you suggested was harmful. It is probably the most direct way to inhibit the NPP system with little or no harmful effects. The only thing I can think of would be the valves never cycling and over time they may freeze up but, maybe not. Having an automatic, it is my opinion that removing that fuse is not necessary. That is my opinion. Which is just that, My Opinion. My purpose was not to attack you but to make everyone aware that there are some problems with the deactivation of NPP and V4 mode. Those with manuals can just never use Eco mode and that’s that. Those of us with automatics have to contend with the V4 sound because there is no mode that it doesn’t activate. My C7 will go into V4 mode at 35 mph in any mode and without NPP it sounds bad. That is the reasoning behind my statement that it is not necessary to remove that fuse. All I can think is that those who like it must not have auto’s. Anyone can pull that fuse and not worry about any harm. I’d recommend everyone to do so and make their own choice. Theta did an excellent job at coming up with the least harmful way of deactivating NPP in a way that is so simple anyone of us can try it. Him and several other members have test this method for months with no negative results. I my self have tried it and decided its not for me.

The reason for the AFM discussion was several members brought it up with some questions and if you have an automatic it is a major factor and consideration in NPP deactivation. The OP never stated which trans he has so it became part of this discussion. I believe the misunderstanding between Theta and I comes from us owning two very different vehicles. Unfortunately deactivation doesn't bode well with automatics.

I apologize to all who think I was attacking Theta. I am a technical person by nature and career and sometimes come across to directly. My focus was not to attack but to bring forward the problems with AFM associated with NPP so that every member especially those with automatics could make an informed choice.
You're correct there - I don't have enough aural experience with the automatic, nor do I know where the drone points are, etc. I do know what you mean (in a generalized sense) having owned multiple versions of the same car (in both manual and automatic). The drone points are different, and what sounds 'right' in one vehicle may not be right in another.

It's all a matter of opinion, and different strokes for different folks. It gets even more complicated if you use a Fusion system, etc. as that changes the drone points.

Where I took offense was the implication that I was spreading data that was potentially harmful. That's never my intention, and in fact, I hold quite a bit of information back (especially with regard to SRS, Airbag, etc) in order to protect users from damage, liability, or harm.

Other than that, we're all good. Question's been answered, and we've drawn some new people into the Fuse 41 fray. Now, the good news is that if you hate it (drone, etc), you simply pop it back in!

If you like it / love it / gotta have it (little food reference there), take a look at the other thread for switch ideas, etc.
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Old 07-14-2014, 10:58 PM
  #51  
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Well, after all that, Klyde accused me of slandering him, etc. So I guess I'm the bad guy here, folks.

No good act goes unpunished on the forums...
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Old 07-14-2014, 11:09 PM
  #52  
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As this question has now been answered and that answer accepted, this thread has run its course. Requesting a lock before this goes any further downhill.
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Old 07-14-2014, 11:16 PM
  #53  
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I've read this thread in it's entirety. There is a lot of excellent information here.


The only thing that I see negative about this thread is the personal attacks.


I will honor your request for a thread close. Keep it clean-no personal attacks.
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