Another good video from Speedkar99..
Why Cylinder Deactivation Can Cause Engine Failure (Honda)
- Thread starter carviewsonic
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IMO, cylinder deactivation is garbage.
Agree. Sacrificing a lot just to squeeze out mpg.
Honda took possibly one of the best and most reliable V6 cylinder engines ever made and turned it into a piece of trash with this to save very little.
I believe government mandated fuel efficiency regulations drive manufacturers to pull out their bag of tricks to achieve each small gain in efficiency.
You forgot to add "with the least amount of R&D and cost". GM has been using the technology for years no?
Some clown made a comment on that video about not buying a 2006 VCM Ody. Normally that guy isn't the sharpest knife in the sock drawer.
See The Critic's pictures/commentary here as well.
See The Critic's pictures/commentary here as well.
Learn something new every day. Thanks for posting. I thought cylinder deactivation just shut down injectors. Didn't know Honda was closing the valves as well. Seems dumb to create all that compression & vacuum for nothing.
They still including this system on their new cars?
They still including this system on their new cars?
The air in the cylinder can act as a spring. Close the valve at any point. If it tries to pull a vacuum, then when the piston comes back up the vacuum helps pull the piston back up. If tries to compress, then when the piston goes down the air pushes down.
It's not 100% efficient but the air (or lack thereof) can act like a spring in these cases.
Was there something they were trying to accomplish / avoid by closing the valves, versus just letting the combustion chamber breathe normally while not feeding it any fuel? Is the 'spring effect' what they were seeking? I would love to understand Honda's logic behind this. They really undercut their reliability reputation with this one. Hope it was worth it.
Pure speculation. Because its a port injected motor and you don't want vapors that might be in the intake running through a non-running cylinder and a potentially cold converter.
Again, pure 100% speculation on my part.
Yeah that's what I was thinking as well.
If the valves are moving a vacuum is still generated brining gas/air into the cylinder in port injection.
Both of which are problematic.
Even in direct injection you would have air being brought into the cylinder possibly, which your now wasting energy compressing air and causing possible pressure issues in the system.
Yes, the spring effect is basically the whole point. Otherwise you have pumping losses sucking fresh air in and shoving it back out. But it is the cause of all of the problems associated with cylinder deactivation. GM has problems with their system: in their case, they use special hydraulic lifters that are activated/deactivated by oil pressure, which is controlled by a solenoid valve. These lifters are prone to failure.
Simply turning the fuel injectors off has already been implemented in just about every vehicle engine made in the last 20+ years (even ones without cylinder deactivation). Any time you take your foot off the gas and let the vehicle coast in gear, the computer shuts all of the injectors off. The only thing keeping the engine spinning is the wheels, until/unless you either step on the gas again, or if the RPM gets too close to idle speed, at which point the injectors will start squirting again.
To reduce the work needed to be done by the rotating assembly to maximize fuel efficiency and minimize engine load while running on 3 cylinders.
Is this true? My impression is that there is always air being introduced even when throttle is closed and therefore should be injecting some minimum amount of fuel while coasting.
Yes, it's true. Just because there's some air being introduced doesn't mean you have to inject fuel too.
Yes it’s true, you can hear it in some cars with noisy injectors. My sons civic for instance does it on the down stroke if you rev it. The strategy varies for mfr to mfr, and auto vs manual transmissions. They will also make sure the engine stays above a certain rpm even decelerating, as needed, to keep power steering and alternator spinning, and it’s a higher “idle” speed while rolling, such as 1300. But if the trans is spinning it above that they will often just shut the injectors off.
Yes, cylinder deactivation is total junk. A previous co-worker of mine had a Honda with this feature and it had major problems with very few miles on the engine. The C-7 Corvettes have had problems with this as well and other GM pickups, Cadillacs and other vehicles. It just doesn't seem to work that well.
