[Martinjlm]

Originally Posted by MakCamaro

I have it and I think it's a great feature. I never notice it when it switches from V8 to V4 and back. I don't see why people want to deactivate it.

Exactly my experience. If I'm not watching the indicator light, I have no idea if it's switching or not. I've watched the indicator switch back and forth and can not hear a difference. There have been times where I've been on the highway in the mid 80s and it's still in V4 mode.

Doesn't hurt me on the performance end either. I've managed to consistently get 12.6 - 12.8 quarters at Milan Dragway, even with a sucky 60'

My last outing I managed 12.8 - 13.4, bone stock + CAI, in 3,200 - 3,400 DA and mid 90 degree temps.

[Petrol Head]

Originally Posted by ember1205

Mmmm... not really.

There are a number of variables like trim level, specific dash configuration, and which screen you're viewing in addition to there possibly being some differences between model years. On mine (2020 2SS, 6MT), as one example, it always shows "V8" when viewing the trip odometer using the standard instrument configuration.

I just noticed that. I never put it in fuel economy or trip odometer mode, and I always keep it on speedometer. The V8 symbol only appears in trip Computer mode which I’ve just glanced at a few times and never looked closely. So that V8 symbol only appears in fuel computer mode on the manuals.

[ember1205]

Originally Posted by Petrol Head

I just noticed that. I never put it in fuel economy or trip odometer mode, and I always keep it on speedometer. The V8 symbol only appears in trip Computer mode which I’ve just glanced at a few times and never looked closely. So that V8 symbol only appears in fuel computer mode on the manuals.

What?! You don't constantly switch around your dash cluster configuration?!?! lol

I have the speedo info in the HUD, so I leave the dash in Trip A mode. I've trained myself over a lot of years of driving to watch that average MPG as a way to keep my right foot a little lighter and keep the numbers as high as I can...

[squish72]

Just want to shed some light, both manual and auto trans engines (lt1) have afm in them. The computers of both have the functionality of engaging it, it's simply just not turned on or activated with the manuals.

Not sure why the op has a manual and says the gauge would change to show v4. I wouldnt think its actually doing what it says it is but obviously something is telling the computer to display that.

Afm is actually a really cool thing when it's working. The issue with afm is that the lifters that change length in order for it to work, get stuck when collapsed. Any time you look up issues with afm there's a huge amount of forums and posts of people that have had problems or issues with it. Most saying it's basically a ticking time bomb of not "if" but "when" it fails.

I have my car tuned and I'm one of the rare cases of still using afm. I no longer have it kick on as early as it used to from the factory. It would constantly kick in and out just driving around town at 40 or so mph. I now have it where it won't engage untill the car is going over 60 mph. When it fails or I have issues I will change it out with non afm parts but untill then I'm going to enjoy traveling and getting 30+ mpg.

So my take away from all this is be aware that the benefit of it doesn't come with out a caution or even a cost down the road, but don't be afraid of it. Just be aware.

[ember1205]

Originally Posted by squish72

Just want to shed some light, both manual and auto trans engines (lt1) have afm in them. The computers of both have the functionality of engaging it, it's simply just not turned on or activated with the manuals.

Not sure why the op has a manual and says the gauge would change to show v4. I wouldnt think its actually doing what it says it is but obviously something is telling the computer to display that.

Afm is actually a really cool thing when it's working. The issue with afm is that the lifters that change length in order for it to work, get stuck when collapsed. Any time you look up issues with afm there's a huge amount of forums and posts of people that have had problems or issues with it. Most saying it's basically a ticking time bomb of not "if" but "when" it fails.

I have my car tuned and I'm one of the rare cases of still using afm. I no longer have it kick on as early as it used to from the factory. It would constantly kick in and out just driving around town at 40 or so mph. I now have it where it won't engage untill the car is going over 60 mph. When it fails or I have issues I will change it out with non afm parts but untill then I'm going to enjoy traveling and getting 30+ mpg.

So my take away from all this is be aware that the benefit of it doesn't come with out a caution or even a cost down the road, but don't be afraid of it. Just be aware.

OP specifically stated he has only seen the V4 indicator show up in online videos, never in his own car.

Yes, the ENGINES have AFM mechanical components in all cars, but the manuals lack the AFM actuators on the exhaust to create the necessary back pressure for when the car would drop to V4 mode. So, the computer has it tuned out.

To compensate for not having AFM in manual transmission cars, GM changed the final gear ratio and added the CAGS system to force the skip second gear under light acceleration from a stop as a way to ensure it could hit the numbers required by the EPA to avoid a gas guzzler tax.

AFM has issues. While I have it in my Silverado and I have not specifically encountered any engine issues -yet- from it, previous versions in the 5.3L engine cause them to burn oil and have general issues with proper lubrication. While the current iterations of it seem to be better, the reality is that there still are not enough high-mileage vehicles out there to prove that it's stable over the long haul.

[UnknownJinX]

Originally Posted by MakCamaro

I have it and I think it's a great feature. I never notice it when it switches from V8 to V4 and back. I don't see why people want to deactivate it.

Old cylinder deactivation mechanisms are not great by any means. And this is not just GM. Honda messed it up, too, when they first put the VCM mechanism on their J35Z V6 engines.

Deactivated cylinders rely on air spring with the gas inside the cylinder. The problem is that there is no such thing as a perfect seal. Over time, the gas inside will leak past the rings or even valves if there is enough carbon buildup. Eventually, the pressure inside will be low enough that it will start sucking in things it's not supposed to, like oil. This is where all the oil burning and the consequent spark plug fouling and catalyst problem come from. OHV engines then have the additional issue with the lifters.

I have heard that GM supposedly combat this issue by having a combustion event once in a while in the deactivated cylinder just to keep the cylinder pressure high. Honda also eventually fixed theirs.

It's one of those things that car companies have to do because of CAFE, but to most end users, it doesn't really matter too much, especially if it has the potential to cause headaches down the road, as it has historically been.

BTW, there are 4-cylinder engines that start doing this as well, like GM and Mazda, which I find pretty ridiculous but that's CAFE for you.

[Nothing like an SS]

Originally Posted by ember1205

OP specifically stated he has only seen the V4 indicator show up in online videos, never in his own car.

Yes, the ENGINES have AFM mechanical components in all cars, but the manuals lack the AFM actuators on the exhaust to create the necessary back pressure for when the car would drop to V4 mode. So, the computer has it tuned out.

To compensate for not having AFM in manual transmission cars, GM changed the final gear ratio and added the CAGS system to force the skip second gear under light acceleration from a stop as a way to ensure it could hit the numbers required by the EPA to avoid a gas guzzler tax.

AFM has issues. While I have it in my Silverado and I have not specifically encountered any engine issues -yet- from it, previous versions in the 5.3L engine cause them to burn oil and have general issues with proper lubrication. While the current iterations of it seem to be better, the reality is that there still are not enough high-mileage vehicles out there to prove that it's stable over the long haul.

I have a 2007 Monte Carlo SS with AFM on the 5.3 LS4. I am just about to clock 100K on the odometer and no issues, car still runs fantastic. The oil burn, well that happens regardless as oil pressure is part of the valve control for AFM (at least on the LS4) and it burned since day 1, it was noted from factory as such, some warning about oil consumption or another. Oil consumption is just the way it is for these. I also have a friend, same car and engine, tuned AFM out YEARS ago, still goes through oil the same rate as I do, so tuned out doesn't change that aspect.
We also did comparison over time, the actual MPG difference with/without AFM? 1-2 mpg on average, not exaclt world changing is it? lol

My Camaro of course does not have it as it is an M6

[ember1205]

Originally Posted by Nothing like an SS

I have a 2007 Monte Carlo SS with AFM on the 5.3 LS4. I am just about to clock 100K on the odometer and no issues, car still runs fantastic. The oil burn, well that happens regardless as oil pressure is part of the valve control for AFM (at least on the LS4), it was noted from factory as such. Oil consumption is just the way ti is for these. I also have a friend, same car and engine, tuned AFM out YEARS ago, still goes through oil the same rate as I do, so tuned out doesn't change that aspect.
We also did comparison over time, the actual MPG difference with/without AFM? 1-2 mpg on average, not exaclt world changing is it? lol

My Camaro of course does not have it as it is an M6

Yep... Plenty of examples of it working just fine in the previous iteration of the 5.3. But, quite a few examples of issues, too. If there weren't as many issues as there are, GM wouldn't have made the significant changes to the engine that they did.

As far as MPG differences being "world-changing"...

My Silverado has 76k miles tracked with an overall average of 16.9MPG. If I got 16MPG instead over that duration, that's a difference of 254 MORE gallons of gas. This would mean that myself and a little over 38 others tracking the same total mileage could fill a tanker truck with gas in what we saved.

15MPG? That would equate to 572 more gallons of gas. At this level, it would take me and only about 16 other people to fill that same truck.

So, yeah... it absolutely can be world-changing when scale is accounted for.

[Nothing like an SS]

Originally Posted by ember1205

As far as MPG differences being "world-changing"...

My Silverado has 76k miles tracked with an overall average of 16.9MPG. If I got 16MPG instead over that duration, that's a difference of 254 MORE gallons of gas. This would mean that myself and a little over 38 others tracking the same total mileage could fill a tanker truck with gas in what we saved.

15MPG? That would equate to 572 more gallons of gas. At this level, it would take me and only about 16 other people to fill that same truck.

So, yeah... it absolutely can be world-changing when scale is accounted for.

All very true, but to be honest, MPG was never a concern for me, even considering the $$$. I would not have had the Monte or the Camaro if that was even a consideration.

So MPG is a matter of perspective, if it matter to you, then it is absolutely important and every little bit will help. If you are not concerned, it just does not matter. The only time I even track MPG is on long road trips, not to see if I can save fuel, but more just curious how it does. I typically drive it like I stole it, so I am not making any MPG records, unless there is a prize for LOWEST MPG! LOL

Cars, all about what matters to you, all good in the end!

[Petrol Head]

Originally Posted by ember1205

What?! You don't constantly switch around your dash cluster configuration?!?! lol

I have the speedo info in the HUD, so I leave the dash in Trip A mode. I've trained myself over a lot of years of driving to watch that average MPG as a way to keep my right foot a little lighter and keep the numbers as high as I can...

MPG? What's that? They seem to advertise this "MPG" whachamacall it a lot with the Prius. Perhaps that would interest you more than a Camaro

[cellsafemode]

Originally Posted by Nothing like an SS

All very true, but to be honest, MPG was never a concern for me, even considering the $$$. I would not have had the Monte or the Camaro if that was even a consideration.

So MPG is a matter of perspective, if it matter to you, then it is absolutely important and every little bit will help. If you are not concerned, it just does not matter. The only time I even track MPG is on long road trips, not to see if I can save fuel, but more just curious how it does. I typically drive it like I stole it, so I am not making any MPG records, unless there is a prize for LOWEST MPG! LOL

Cars, all about what matters to you, all good in the end!

he wasn't saying that everyone would care.

What's not a matter of perspective is the reality that even 1mpg differences quickly add up to significant amounts of fuel in short amounts of time.

I can not care about entire countries existing ...that doesn't mean them existing doesn't impact me in a way i'm not aware of or dont have a reference to.

We may not buy the camaro because it is slightly more fuel efficient than some alternative sports car. But it's able to be faster and be as powerful as it is by being more efficient in burning every drop of fuel and that equates to better mileage/power at any rpm band. So it matters even if you average single digits, since what he's counting at the opposite end is connected to the same thing allowing you to drive it like you stole at your end.

[ember1205]

Originally Posted by Nothing like an SS

All very true, but to be honest, MPG was never a concern for me, even considering the $$$. I would not have had the Monte or the Camaro if that was even a consideration.

So MPG is a matter of perspective, if it matter to you, then it is absolutely important and every little bit will help. If you are not concerned, it just does not matter. The only time I even track MPG is on long road trips, not to see if I can save fuel, but more just curious how it does. I typically drive it like I stole it, so I am not making any MPG records, unless there is a prize for LOWEST MPG! LOL

Cars, all about what matters to you, all good in the end!

Understood. My point was that the MPG Police are focused on scale and not individuals, while as individuals we often lost sight of the scale of things. Is the specific MPG of my truck saving the world? Nope. Not a chance. But if the AFM helps ME to lower fuel consumption, then that might be making some useful difference at scale.

Incidentally, I love to listen to people cry about the cost of premium fuel in a 50k vehicle because it's actually quite laughable. I've spent $10,000 on gas to drive 76k miles using 87 octane. If I had to use 93 (like the Camaro), that cost would be about $13,000. Not all that earth-shattering when you look at it in perspective.

Originally Posted by Petrol Head

MPG? What's that?

I keep the speedo on both places just so I don't end up in jail.

I hear that!

[ember1205]

Originally Posted by Petrol Head

MPG? What's that? They seem to advertise this "MPG" whachamacall it a lot with the Prius. Perhaps that would interest you more than a Camaro

I wonder how much it costs to feed those squirrels that run the drivetrain, though. All they ever talk about is saving on fuel and fuel costs, but they never mention the habitrail...

[Nothing like an SS]

Originally Posted by cellsafemode

he wasn't saying that everyone would care.

What's not a matter of perspective is the reality that even 1mpg differences quickly add up to significant amounts of fuel in short amounts of time.

I can not care about entire countries existing ...that doesn't mean them existing doesn't impact me in a way i'm not aware of or dont have a reference to.

We may not buy the camaro because it is slightly more fuel efficient than some alternative sports car. But it's able to be faster and be as powerful as it is by being more efficient in burning every drop of fuel and that equates to better mileage/power at any rpm band. So it matters even if you average single digits, since what he's counting at the opposite end is connected to the same thing allowing you to drive it like you stole at your end.

Totally agree, but my comments were a little more off cuff and sort of tongue in cheek, but I guess that escaped you. Like the comment that followed "What's MPG?" It was more an LOL than anything else, but thanks for the comprehension lesson.

Things get uptight around here quick!