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Having driven several cars with start/stop, and currently owning one with cylinder deactivation, I don't understand what all the fuss is about. Yes, it is a little weird at first to be stopped at a light, and have no vibration or sound.
What the fuss is about? The fuss is that even the best start/stop system has lag. Meaning, the time between when you release the brake pedal and put your foot on the gas and go forward. I've tried many of the systems out there and none can disengage the brake, start the engine, and engage throttle faster than you can let off the brake and hit the gas. That lag, even a fraction of a second is noticable and quite annoying. Also, try entering a parking space, realizing you need to go forward a little bit, and then fight the car to allow you to do so. No, just no.
Last edited by Atari_Prime; 02-18-2020 at 03:34 PM.
Having driven several cars with start/stop, and currently owning one with cylinder deactivation, I don't understand what all the fuss is about. Yes, it is a little weird at first to be stopped at a light, and have no vibration or sound.
Wife has had 2 BMW X5 SUVs. Her 2014 was like her new one- Stop[/Start is seamless! The engine starts faster than your foot can get from the Brake to the Throttle. In fact, with the sound system playing don't even hear it start.
Some companies are using a sophisticated starting assist method. They shut the engine off when the piston is just over TDC where combustion occurred. The pressure in that cylinder helps get the engine started with "the assistance of the starter motor!" It reminds me of the emergency method used on some WWII airplanes. A large caliber black was fired in a cylinder to turn and start the engine!
Don't know if BMW is using that approach but it's seamless and I seldom "shut it off!" The only time I do is when my wife is not with me and I put in in Sport Mode to have fun! It also has an interesting simple method to recover some braking and costing energy. It has a second large AMG battery and the alienator only charges when coating of braking. Every little bit helps get more than the about 14% of the energy in gasoline that gets to propel the car! The rest is wasted! We can do better before being forced into foolish EVs, IMO!
All cars are not as good! The cheap model rental cars I have driven with it were poor!
Wife has had 2 BMW X5 SUVs. Her 2014 was like her new one- Stop[/Start is seamless! The engine starts faster than your foot can get from the Brake to the Throttle.
What the fuss is about? The fuss is that even the best start/stop system has lag. Meaning, the time between when you release the brake pedal and put your foot on the gas and go forward. I've tried many of the systems out there and none can disengage the brake, start the engine, and engage throttle faster than you can let off the brake and hit the gas. That lag, even a fraction of a second is noticable and quite annoying. Also, try entering a parking space, realizing you need to go forward a little bit, and then fight the car to allow you to do so. No, just no.
Yes, thanks to that lag (in my 2018 Malibu) I almost got flattened by a dump truck when pulling out of a side road. Now I always drive without 'engine off' mode.
The pressure in that cylinder helps get the engine started with "the assistance of the starter motor!" It reminds me of the emergency method used on some WWII airplanes. A large caliber black was fired in a cylinder to turn and start the engine!
I believe this is incorrect. The Coffman starter system did not use the engine's cylinders but rather its own cylinder driving a screw gear.
Also, if you use the paddles and shift manually, it does not enable cylinder de-activation. This will work for me at first, as I will hardly drive the car in automatic mode anyway.
I, for one, despise the technology and plan on getting the Range device for my car as soon as it becomes available for the C8 generation of 'Vettes. On those rare times when I do want to drive it in auto, I won't have to worry about that damn feature coming on.
If you read, an if you understood prior post about AFM information already posted, that I'm re-posting, you can see Tadge reply to your same question, with all the ways to do it. The part I highlighted, seem to do what you want, when your driving. My plan is to use it, if I should have a problem with the feel of AFM or for that matter stock shifts programing. I see no need for an aftermarket product like you've posted.
I'm sure Z mode programing will be a challenge for me at1st, but I believe I can figure out how to do, if not with the help of others, program Z mode to shift in a manner I like the feel of with AFM disabled.
That when I get in the car, an start it my Z mode programed shifts will be available at start.
Will the C8 be running in AFM mode by default?The original answer thread is here.
fatsport asked:
Quote: Can AFM be turned off by putting the car in manual mode? How long before it goes back to auto mode?
Assuming I purchase a Z51 with magnetic ride, can I disable AFM by putting it in PTM? Tadge answered:
Quote:
We know some customers are not fans of AFM (Active Fuel Management, otherwise known as cylinder de-activation). They worry it will sound bad, or feel bad as it transitions in and out of V4 mode, or just don't like that the engine doesn't always run on all cylinders. Manufacturers around the world are being put under tremendous pressure to reduce fuel consumption and greenhouse gases. As a result, you see a massive move to electrification, hybridization and small displacement charged engines. General Motors is fully embracing the initiative and has a stated goal to get to a zero emissions future.
So how does Corvette fit into this picture? Even before global greenhouse gas concerns became mainstream, Corvette prided itself on efficient operation. After all, low mass, low drag and efficient engines make for a better sports car. There are a lot of ways to get fuel efficiency and some of them negatively impact the driving experience. Our manual transmission skip-shift we had for years was not a customer favorite, but it helped economy and kept us away from gas-guzzler taxes. The bottom line is that we have to make choices that balance the owner's experience (including operating cost) and our impact on the planet.
Our AFM system is very effective on the small block V8. It lets us close the valves on the de-activated cylinders so the cylinders act as air springs. When the engine rotates we get energy back as the compressed air in the cylinder expands. Other manufacturers just stop fueling the de-activated cylinders and so don't get much fuel savings. The reason 4-cylinder operation is more efficient is that the active cylinders are worked harder with a greater throttle opening. That's like taking a restrictor out of the system saving pumping losses. On Corvette, AFM saves more fuel than start/stop, a feature becoming very prevalent in the marketplace. For many cars, start/stop is a great choice because it is almost transparent to the occupants. Not so on a Corvette. Our engine has a lot of character, so when it stops running it is very noticeable. We have received a lot of very strong input from customers that they would not like it.
One of the innovations on the 2020 Stingray is the integration of AFM with a DCT. We a quite proud of how seamless we've been able to make it. We believe we are getting the efficiency benefit with virtually no compromise to the driving experience. Numerous drive impression articles have been written and I do not remember reading any negative comments about it. Bottom line is that we must balance conflicting demands and make smart choices so we can continue to offer the driving pleasure of a naturally aspirated V8 engine.
________________________________________ ________________________________________ ________________________________________ ________________________________________ ________________________________________ ________________________________
So now to the heart of your question. Yes, when you are in manual mode the engine stays in V8. That is true either by hitting the "M" button or by entering "temporary tap" by pulling one of the paddles. Temporary tap will revert to "Drive" after about 5 seconds if you don't request an additional shift in that time. AFM is also de-activated in "Track" mode. Since PTM is only available in Track mode, the answer is yes to that one too. If you are in PTM, it will be V8 only. New for 2020 is the "Z" mode which will come from the factory set up as an extra sporty mode including shift schedules pulled from the "Track" mode, so that will be V8 only. Of course, you can customize "Z" mode any way you want, so if you elect another shift pattern, AFM will return.
The 2020 Vette does not have start/stop technology (thankfully), however it does have cylinder deactivation (unfortunately). Does anyone know if the deactivation feature can be turned off either temporarily or permanently?
Thx.
It turns off nicely on the M7 C7...but I digress.
Last edited by Big Lebowski; 02-18-2020 at 05:30 PM.
Hey all. (first post!) In my experience, I would say that the level of frustration from start-stop varies wildly from car to car. My wife's Jaguar F-Pace (S Model, 2018) is extremely annoying when it transitions. It's slow, and clunky. You can actually feel it from the drivers seat when you're slowing to a stop and it turns on and off. I've long since learned to press the button to turn it off as part of my start up routine in that car. But by comparison, we just recently bought a new 2020 Kia Telluride (needed a 3 row suv) and its start-stop function is SO smooth and un-noticeable that I'm actually not sure it's working! I see the light turn off and on from time to time but that's about it.
My C8 will be the first car I've owned with cylinder de-activation so I have no opinions on that yet. Is it really noticeable when cruising on the highway? Does throttle response or the sound of the exhaust change when it switches in and out of 4 cylinder mode?
^^^^
People that hate cylinder de-activation come up with all sorts of reasons to hate it. In reality, it's seamless.
I had a 2013 Camaro with it. Engine failed 6 months out of warranty. I had it fixed (by a dealership) and it failed again before a year was up for the same reason. There's a damn service bulletin about looking for the issue. No thanks, no cylinder deactivation.
Hey all. (first post!) In my experience, I would say that the level of frustration from start-stop varies wildly from car to car. My wife's Jaguar F-Pace (S Model, 2018) is extremely annoying when it transitions. It's slow, and clunky. You can actually feel it from the drivers seat when you're slowing to a stop and it turns on and off. I've long since learned to press the button to turn it off as part of my start up routine in that car. But by comparison, we just recently bought a new 2020 Kia Telluride (needed a 3 row suv) and its start-stop function is SO smooth and un-noticeable that I'm actually not sure it's working! I see the light turn off and on from time to time but that's about it.
My C8 will be the first car I've owned with cylinder de-activation so I have no opinions on that yet. Is it really noticeable when cruising on the highway? Does throttle response or the sound of the exhaust change when it switches in and out of 4 cylinder mode?
My wife drives an F-Pace too and completely agree with you. Stop/start is noticeably annoying, so much so I disconnected it completely so we no longer need to remember to push the button on startup. You can find instructions online and on one of the Jaguar forums; not hard to do. Stop/start is particularly annoying (on any car) in rush hour traffic.
I'm glad stop/start is not a feature on the C8. Cylinder deactivation, on the other hand, is not a big deal and pretty seamless when cruising (not like the old Cadillac days). If the C7 is any example, the C8 should be good.
^^^^
People that hate cylinder de-activation come up with all sorts of reasons to hate it. In reality, it's seamless.
I'm no tree hugger. My street rod with a 502 CID BB gets ~10 mpg! Don't drive it often! However for my DD willing to do what I can to save some wasted energy. If we don't it just reinforces those who will push gasoline prices up until EVs (which IMO are a bad solution) are the only choice. Understand many folks don't understand (or some don't care) but this graphic presents the latest AVERAGE USAGE DATA showing where the energy in gasoline goes! It is an average so yep all highway driving doesn't save much BUT 11% of the energy is gasoline is wasted idling. Much of that can be saved. Also 5% of the energy that gets to the rear wheels is ultimately wasted braking. Much of that can be captured. It total ONLY ~14% of the energy gets to propel the car forward!
Some who hate all this "stuff" and will be the first to say, "What Happened" when gas tax gets like Europe and we're paying $10/gallon and are "economically forced" to what I think is a poor solution- EV's. Best to do all we can to postpone that choice.
the problem with these software based deactivation devices is that while it will not activate, it does not prevent a failure of the deactivation system.
My opinion? Unless they can be flashed AND the associated hardware removed/changed out for aftermarket parts, keep it on and enjoy the extra 1mpg on the highway.
orrrrr use manual shift mode.
“It [Range] does not prevent a failure of the deactivation system.”. <<=. Sorry, that statement makes zero sense. What exactly is a failure of the deactivation system? How does it manifest itself?
As for the Range device you really need to read up on how it works. Here’s the short version. AFM works under certain light load driving conditions to maximize fuel economy by deactivating 4 of the engines 8 cylinders. The engine control module (ECM) commands the AFM system to deactivate 4 cylinders. The Range device simply intercepts the control modules AFM command (signal) so it’s not passed onto the AFM system.
My wife drives an F-Pace too and completely agree with you. Stop/start is noticeably annoying, so much so I disconnected it completely so we no longer need to remember to push the button on startup. You can find instructions online and on one of the Jaguar forums; not hard to do. Stop/start is particularly annoying (on any car) in rush hour traffic.
I'm glad stop/start is not a feature on the C8. Cylinder deactivation, on the other hand, is not a big deal and pretty seamless when cruising (not like the old Cadillac days). If the C7 is any example, the C8 should be good.
we don’t drive an F Pace, but wife and I both drive MB. The start stop is seamless and barely noticeable. There is a dash switch to turn it off but we leave it on. I just hit the gas and it goes. It is a good feature with some of the extraordinarily long lights we have here. The engine starts in a split second so I’m not sure about a n extra load on the starter or battery.
It annoyed me at first, but now I dig Start Stop for long lights and drive thrus. Most of the cars I've driven over the last few years (quite a few rentals) have had it. Most of them a simple half-lift on the brake and re-press triggers the motor to come back on and stay on (learned this on a truck I had as a rental in cold weather and I wanted the heater to warm up). When the crosswalk goes to red or the cross traffic goes yellow, lift the brake for a fraction of a second and the motor is ready.
My wife's Hybrid Lexus there's no lag at all, and driving can even swap off the motor and uses battery when cruising. Still seems a bit odd having a car that gets better mileage in the city then on the highway.
I know technology can be hard for some of older folks, but you can always ask your grandkids (OMG just kidding).
02-18-2020, 03:33 PM
Wife has had 2 BMW X5 SUVs. Her 2014 was like her new one- Stop[/Start is seamless! The engine starts faster than your foot can get from the Brake to the Throttle. In fact, with the sound system playing don't even hear it start.
