Cylinder Deactivation

[Snax]

I don't follow how valves could burn up without any fuel going into the cylinders. That effectively reduces them to being air pumps - and still a parasitic drag on the motor.

Another idea which might be more practical to retrofit without sacrificing power capacity would be to incorporate injector shutoff along with butterfly valves the close in the intake runners to the affected cylinders. Exhaust reversion back from the header may actually help to push the cylinder down if enough vacuum is created. That might make for some funky header tuning which actually encourages some restriction at the collector for improved economy.

I'm just thinking out loud here though.

[atomgonuclear]

ok OMGWTFBYOBBF

you are wrong in a lot of what you said

you obviously have VERY little to no technical knowledge on engine management whatsoever and I'm actually angry after reading all of the bull**** you just posted

THE DIY version of this is impossible for anybody to do, it has to be incorporated into the car at the factory when it is built(or unless you have a very good machine shop and know your ****), you cannot just disable fuel injectors and hope that it works it will not. There is no way to control the opening and closing of the valves with a possitive driven system.

Right now there is very little to no cars that have Variable valve timing that would be able to completely keep the valves closed, right now they only run staging systems which uses offset lobes to change timing (Sorry Vtech guys). If you wanted to completely control open and closing of the valves you only see that in the highest end cars by Lotus, which use solenoids instead of a camshaft for an infinite amount of positions using PWM. The biggest part of the system you left out was the airspring.

for two
A lot of cars currently are designed for batch or bank firing injection. This means that all the injectors are firing at a time or half of them are. Sequential injection is only something seen on some modern cars, but not all. Depending on the firing order, it would be impossible to balance the crank by 180 degrees of the opposite firing cylinder without sequential injection. Say byebye to those cheezy import rubber motor mounts.
also
Its impossible on a stock TBI injected engine since you only have 1-4 injectors, but not specific to the cylinders, so you would be running rich and need new fuelmaps.

btw..... megasquirt only supports batch and bank firing, not sequential, I just built one last week

three,
no..... the pressure in the crankcase is hardly even affecting the cylinder going down, you went on and on and on and on about static delta sigma cappa flappa mappa pressures in the crankcase offset the pressure in the cylinder...... THEY DONT, didnt you ever hear of a crank case vent?? I guess not. What about a pcv valve? Nah? figures.... because both of these things compensate for that pressure. Thats why it blows off in boosted engines with bad pistons rings.

"Anyway, as for your first experiment, cutting fuel to two cylinders, you should see some increase in mileage. Removing the injectors from those holes should net a larger increase in efficiency."

no you cant pull out the fuel injectors that would be a huge vaccume leak, not to mention the way you put it made it seem like the injectors go right into the cylinder. hahaha

you cant just stop using the injectors because you'd get wack readings on your oxygen sensor

did you ever have a coilpack go bad?? I guess not, you get crazy vibrations

But all in all....... there is many many more topics I would like to touch on but I cant think of them right now(like how boost gives you more pressure than your engine can handle and you dont need to worry about pumping loss). I'm not saying that this is impossible but I'm saying the average DIYer can and will never accomplish this task. If it was so easy I'm shure the great minds behind billions of dollars worth of companies would have thought about it already.

btw never compare diesel to regular petrol its a whole different animal

might as well compare gunpowder to rocketfuel

[trebuchet03]

Originally Posted by atomgonuclear

you obviously have VERY little to no technical knowledge on engine management whatsoever and I'm actually angry after reading all of the bull**** you just posted

Way to start with a personal attack The rest of your post just isn't worth reading after that

[Snax]

Dude! Two words: Anger management.

Just remember that there are people on this board who are not the 'average DIYer'. We are willing to try some extreme, odd, and just plain silly **** to satisfy a curiosity.

Sometimes the joy in inventing is the process of discovery, not the achievement of success.

Also don't discount the ture interests of billions of dollars of research. GM didn't kill the EV-1 because of a lack of demand or a failure of the technology. Similarly, consumer demand has not made FE a priority. Just watch what happens when fuel starts costing twice what it does now. People will stop demanding every option in favor of a car that they can actually afford to fuel.

Cylinder deactivation is very valid concept worth exploring. If it takes sequential injection to make it work dynamically, then that is what it takes. Don't assume that people will not be able to implement it. Likewise, a proper tune for open loop operation makes the oxygen sensor superfluous. There's no reason open loop could not be the default there.

We see allot of pie-in-the-sky stuff on here, but a few gems like wheel skirting and grille blocking offer undeniable benefit to some on vehicles where the manufacturers just never bothered to consider offering them.

[GasSavers_Red]

Random blurb. A 2000 Toyota Camry w/ 1MZ-FE V6 engine can start and run on 3 cylinders. The key seems to be taking out cylinders 1, 2, and 5 for some reason. My dad slagged the ignition coils on them somehow and according to him it was running fine. Less power, but could cruise at 65 MPH w/out problems

[v6camrydriver]

Thoughts and feedback welcome on the following scheme:
Engine: 1994 Toyota Camry 3VZ-FE CAT (3L V6 non-VVT-I)
Transmission: 4-speed automatic FWD transaxle with lock-up Torque Converter
Odometer: 340,000Km
Fuel injection system: Sequential multi-point fuel injection EFI
Oxygen sensors: 3 total: 1 on each engine exhaust manifold and 1 sub-oxygen sensor mounted downstream of the Catalytic converter (CAT)
Firing order: 1-2-3-4-5-6
Current average fuel economy: 10L/100Km
The plan:
Through testing of the engine I have found that it stills runs reasonably well on 3 or 4 cylinders for cruising.
I intend to have three modes of operation:
Normal (all 6) for start-up, warm-up and acceleration
V4 (4 cylinders) for high-speed cruising
I3 (3 cylinders) for low-speed cruising.
For 3 cylinder mode I will deactivate cylinders 2, 4 and 6 (the front bank) and for 4 cylinder mode I will deactivate cylinders 2 and 6. I have found these configurations the smoothest.
I also intend to deactivate the oxygen sensor for the disabled bank and the sub-oxygen sensor. The sensor for the running bank (cylinders 1, 3 and 5) will remain untouched.
The reason for this is it will either:
A: trick the control computer (ECU) into thinking everything?s normal and not just dumping more fuel into compensate, negating any economy gains; or
B: put the ECU into ?Limp-home mode?, which will cause the ECM to substitute pre-programmed values for the turned-off sensors, which since my engine is well maintained should run like normal when at operating temperature.
The method by which I will deactivate the cylinders/oxygen sensors is by rigging up a bank of centre-console switches to turn off power to the appropriate fuel injectors and Oxygen sensors.
The intake and exhaust valves will not be deactivated so the deactivated cylinders will act like air pumps.
The idea is to rig everything up and then do fuel economy tests in various modes to find out what effect it has on fuel economy. But before I do I want to make sure the engine will handle everything (i.e. by not blowing up), both short and long term, so would like opinions/constructive abuse on whether it?s a good idea.
Potential worries to consider:
-uneven wear
-uneven cooling
-deactivated cylinders not being lubricated properly
-burning intakes valves due to no cooling fuel passing over them
-extra oil consumption due to lack of sealing pressure on deactivated piston rings
-shorting or arching when flicking the switches, at best blown fuse, at worst blown ECU
-mechanical failure of connecting rods, pistons, bearings, engine mounts
-Fuel economy gains offset by engine overcoming pumping losses

[GasSavers_RoadWarrior]

All I've seen "proven" is that anemically powered 4 cylinder cars with anal ECUs don't like to have injectors disconnected.... who'd a thunk, it needs all 4 hamsters running to move it at all...

[theholycow]

Well, since this ancient thread has already been bumped...

Originally Posted by rh77

Some of today's modern V-8 and V-6 engines utilize a complex mechanism known as "cylinder deactivation" or "displacement on demand". This feature is reserved for the newest models [...]
This author has brainstormed with this idea before it has become mainstream

That makes it sound like it's a new, novel idea. It was actually used on production vehicles decades ago.
http://en.wikipedia.org/wiki/Variabl...cement#History
Cadillac sold it in 1981 but it sucked at the time.
Mitsubishi sold it in a 4 cylinder engine in 1982 and it didn't suck, but nobody cared. They started again, and again using a 4 cylinder engine, in 1993, and apparently it was even better, but still nobody cared so it was dropped in 1996.

GM failed in 1981 due to lackluster engineering. Mitsubishi failed in 1982 due to market share and the fact that their 4 cylinder engine was probably already not wasting much gas anyway. Mitsubishi failed again in the 1990s because gas was so cheap and again the 4 cylinder thing.

Then I read this: "The Hefley Engine Company is currently developing a unique variable displacement engine that has the ability to change compression ratios and can run on regular gasoline at low compression, then change to diesel where high compression is required." LOL, WTF? Okay there, Dr. Frankenstein, that sounds like a practical and worthwhile engine for a mass-produced car...however, after reading the article, I imagine some of the technologies could be used for actual practical purposes, too.

[suspendedhatch]

Originally Posted by trebuchet03

Way to start with a personal attack The rest of your post just isn't worth reading after that

atomgonuclear has no tact, but some of what he posted IS worth reading because it's true. I didn't read all three pages but I see no reason for him to be offensive. A more confident and mature person would have set a constructive tone.

Where he's wrong is when he implies that only the newest high end vehicles use sequential injection. The Honda Civic has had it since about 1990 across all of the available FI engines. And this is an economy car. Toyota was slower to adopt it on their low end cars but I assure you that all of their USDM 4 cylinder 96+ cars feature sequential fuel injection. It certainly sounds like he is quoting an unrevised text book on that one.

He's also wrong in his assumption that there is nothing to be gained from such an experiment and that if there were mpg gains to be had, the manufacturer would have implemented them. Such an implementation would have been very expensive to develop and manufacture and there would be very low demand for it. It's likely to cause hiccups in drivability that are not acceptable for a production vehicle but which may not matter to someone on this forum.

[suspendedhatch]

Originally Posted by rh77

During coasting, this model of vehicle pulses fuel into the cylinders.

I'm sorry but this is wrong. All fuel injected Hondas and Acuras from 1990 and later do in fact utilize DFCO, Deceleration fuel cut off, which is the strategy this person describes. All fuel injectors remain shut when throttle % is 0 and RPMs are above 1000 RPM.

Besides knowing this to be fact I have witnessed it having installed an AEM wideband gauge type O2 sensor on my own personal 93 Honda Civic DX automatic and later on my 92 Civic VX.

All USDM cars from 96 and on (and many cars older than that) utilize DFCO.