Manually Controllable Cylinder Deactivation

[Saint_Shroomie]

Does anyone know why there isn't a vehicle, at least that I'm aware of, that allows the driver to control how many active cylinders there are. I realize there are cars with cylinder deactivation, but from what I know, the ECU decides when to deactivate cylinders, based on driving conditions.

After doing some thinking the only thing that stops me from buying an SS as my daily driver is the idea of a high torque RWD vehicle in snowy Maryland winters. If I had the ability to deactivate cylinders (and by extension torque) at will, then I could just drop some snow tires on my car as usual and ride out the winter on 4 or 6 cylinders. Then come spring go back up to 8.

Is there any sort of engineering reason that makes something like this prohibitively expensive or simply not feasible?

[DGthe3]

Every car comes with a built in driver controlable, infinitely variable, torque modulation device. It allows you to control the approximate percentage of an engines maximum torque from near 0 to 100%. It is called the 'accelerator pedal'. Leave your foot off it, and the car will produce enough torque to keep itself running. Push it all the way to the floor, and the engine will give you all the torque that it can. Most drivers back off on the accelerator when they notice that they are spinning their wheels and do not need a separate input system to control their engine.

[Saint_Shroomie]

Fair enough, but do you know the answer to my actual question?

[Sir Nuke]

Originally Posted by Saint_Shroomie

Fair enough, but do you know the answer to my actual question?

actually the reason that there isn't a "manual" deactivation set up is for basically two core reasons.
1. Not enough interest.....if the public wanted it....the aftermarket would have most likely hade it happen.
2. Its not as simple as turning off 4 cylinders.....which is why the AFM system is computer controlled.

[FenwickHockey65]

Yes it's possible with a lot of caveats, so no it will never happen.

[Buster452]

Can one just load a super economy mode tune that detunes the power output?

I haven't done reprogramming in years, but my old diesel allowed multiple maps to be loaded and switched by jumping two pins on the odbii port. Can our camaro do that?

[DGthe3]

Originally Posted by Saint_Shroomie

Fair enough, but do you know the answer to my actual question?

From a purely technical perspective, it would be dead simple to have a 'force on AFM on' switch. It would basically be a manual over-ride for the otherwise automatic system. But there are probably a bunch of reasons, ranging from engine longevity to emissions control that likely prohibit GM or any other automaker from implementing it (aside from lack of demand)

Originally Posted by Buster452

Can one just load a super economy mode tune that detunes the power output?

I haven't done reprogramming in years, but my old diesel allowed multiple maps to be loaded and switched by jumping two pins on the odbii port. Can our camaro do that?

With a diesel, you can set a different boost level (which therefore requires a different amount of fuel). If you somehow dial the boost all the way back to 0, and you essentially get a naturally aspirated engine. At that point, there is only so much that can be done to reduce fuel consumption via electronic tuning.

Additionally, one of the things that a tune does is lean out the air/fuel mix. They tend to run rich from the factory as a way to prevent pre-ignition and to improve emissions. The consequences of this are slightly reduced power & a slight drop in fuel economy. So its not as easy as less power = better fuel economy

But beyond that, the way you drive has a much bigger impact on fuel economy than anything that a selectable tune could offer.

[trodecke]

Originally Posted by DGthe3

Leave your foot off it, and the car will produce enough torque to keep itself running.

When I got caught in the ice/sleet/snow storm earlier this year, for the first time in my life, just the idle of the car was enough to spin the tires and send me on a slow motion (very slow motion) spin towards a concrete barrier on I-44. I was on an onramp that was banked to the right while it turned to the right. I was going uphill, turning to the right, while on about a 10 degree embankment sliding at about 1 mile an hour towards the barrier. While I wasn't freaking out I was wondering how difficult it would be to get out and shove against the wall to try to get my car away from it.

[Saint_Shroomie]

Originally Posted by trodecke

When I got caught in the ice/sleet/snow storm earlier this year, for the first time in my life, just the idle of the car was enough to spin the tires and send me on a slow motion (very slow motion) spin towards a concrete barrier on I-44. I was on an onramp that was banked to the right while it turned to the right. I was going uphill, turning to the right, while on about a 10 degree embankment sliding at about 1 mile an hour towards the barrier. While I wasn't freaking out I was wondering how difficult it would be to get out and shove against the wall to try to get my car away from it.

Did you have snow tires on her?

[trodecke]

Originally Posted by Saint_Shroomie

Did you have snow tires on her?

In Oklahoma we get 5 - 10 days of snow a year. Except for January and February, the temps rarely get below 32. For the days that snow is predicted (or already on the ground), I find another way to work. That particular day was kind of a surprise to all of us.

[derklug1]

While cylinder deactivation is an easy engineering solution, I doubt it would be popular enough to justify the switch and two wires. Some cars have a second gear start button which basically does the same thing. I wonder if you had a switch to manually go 4-6-8, would the manufacturer have to certify the emissions and fuel economy in all three modes. Could end up being a regulatory nightmare for the company.

[matt55]

http://carsofchange.com/top-stories/...icient-driver/

Kind of the same , remaps the engine and trans to get better mpg ...

[matt55]

But the short answer is the manufacturer thinks they knows better than the driver does when to cut cylinders. 99% of the time they would be right .

[truth411]

Originally Posted by DGthe3

Every car comes with a built in driver controlable, infinitely variable, torque modulation device. It allows you to control the approximate percentage of an engines maximum torque from near 0 to 100%. It is called the 'accelerator pedal'. Leave your foot off it, and the car will produce enough torque to keep itself running. Push it all the way to the floor, and the engine will give you all the torque that it can. Most drivers back off on the accelerator when they notice that they are spinning their wheels and do not need a separate input system to control their engine.

LMAO!!!