...and deactivated cylinders separated by two strokes instead of one.

My car probably wouldn't work well for this, since it's an automatic; with more throttle, the ECM unlocks the TCC clutch and FE goes to Hell. Any efficiency gains would be soaked up by the torque converter.

...and deactivated cylinders separated by two strokes instead of one.

My car probably wouldn't work well for this, since it's an automatic; with more throttle, the ECM unlocks the TCC clutch and FE goes to Hell. Any efficiency gains would be soaked up by the torque converter.

Yeah... That's the problem with automatics and their kick-down crap. In a situation like this turning it off from the cab would be the best bet since the driver could cut fuel under low load/flat ground/low speed, so the automatic wouldn't upshift. But, this is something that's ultimately best for a M/T... Sure wish my pickup wasn't carb'd, I bet this could result in some serious FE increases with the right setup. :(

I mentioned earlier that my `78 (carbureted) Malibu got its best mileage with a couple of cylinders effectively deactivated by worn-out cams...if you wanted to simulate this on your P/U and can tolerate a serious decrease in power, just pull the rocker arms on a couple of cylinders. If it won't start, pull the plugs on those cylinders as well.

You may want to try pulling plug wires on a couple of cylinders first to verify which pair gives the smoothest operation.

re: deactivating cylinders, seems to me that a flat 4 engine could be split into two flat 2 engines that had a clutch (or in-out box) between them that are both reasonably balanced in themselves.

So I can do this with a carb'd engine? Does the carb just mix a certain amount of fuel with a certain amount of air, so with two valves not opening, the carb just won't mix any fuel in? Regarding ECUs, they're kinda wonky ime. For instance, it took ~50-100 miles for the CEL to go off when I hadn't properly installed my heated O2 sensor. I was able to pass smog by reseting the ECU a day before the check.

The carb just sits on top of the engine and mixes air and fuel. It doesn't care much where it goes.

GM did a concept car based on this a few decades back, though it was two larger engines instead and each was at a different end of the car to optimize F/R weight ratio. The main problem was that the second engine, which was only used for acceleration, was always too cold to work efficiently.

Sweet. And I just need to make sure that I'm deactivating two cylinders that move together, like 1 and 4 or 2 and 3.

That'd be my recommendation.

I'd tend to think deactivating 1 and 4 would be preferable over 2 and 3; 2 and 3 should run a bit hotter than 1 and 4, since they're adjacent to each other, and engines like to run hot.

Like I said, try pulling some plug wires first and trying some different combinations before you commit to minor surgery. You may decide that even if you use the correct 2 cylinders, it's still too rough or underpowered.

Having traveled this road and beat it up pretty badly, here's my 2 cents.

First, just eliminating the ignition to one or more cylinders doesn't do anything except make the car run like garbage.

Second, in order for this to work, you have to disable the valves opening and closing on the cylinder or cylinders which you are attempting to disable. However, pulling the pistons is a problem because crankshafts have oil journals from one crank to the next. If you pull a connecting rod and piston, you will lose your oil pressure and syanora. (Don't know the spelling) If you pull your rocker arms, you have the same fundamental problem, they rocker arm is hollow, allowing oil to flow, under pressure, to all of the rockers. If you pull a rocker, again, no oil.

Their are at least two possible alternatives, although I'm sure their are more.

One, if you remove the rocker, replace the rocker with a modified rocker, which is shortened on both ends, to maintain the oil pressure. This presumes you do both the intake and exhaust valves, on any given cylinder.

Two, if you took a VTEC engine, maybe you could get the camshaft reground, to allow the timing to stay the same, but just disable one or two of the cylinders. I believe this is what Honda is probably doing on their V6 engines

Short of those two, or something similar, just eliminating the fuel or the ignition to the cylinder is just going to give you a rough running engine.

I know this is an old thread. But given the fact that a new link was made to it from a new thread about cyliner deactivation, I thought that I should clear something up here. Specifically, this is NOT right about the firing of an inline four cylinder engine. Cylinders 1 and 3 do NOT fire simultaneouly, or even move in the same direction with one another (ie TDC and BDC does NOT occur simultaneously). The same goes for cylinders two and four. Rather, cylinders 2 and 3 move together with each other, and cylinders 1 and 4 also move with one another. BUT, cylinders 2 and 3 are 180 degrees out of phase with cylinders 1 and 2. So while 1 and 4 are at TDC, 2 and 3 are at BDC.

Also, although 1 and 4, and 2 and 3 both move as pairs, they do NOT fire together. Basically, when one cylinder of the pair (1 and 4, or 2 and 3) fires, the other is in intake stroke. In this manner, you get the firing order of 1342 (NOT 1324) for a typical inline four.

Therefore, in order to deactivate two cylinders in the smoothest manner possible, it is necessary to deactivate every other cylinder to fire. This means deactivating either one and four, or two and three. Deactiating one and three, or two and four will result in EXTREMELY rough running.

It's been forever since I did that test, and background research.

If I remember properly, I tried a variety of cylinder pairs and ended up with the smoothest two.

The main conclusion to draw from the whole experience is that the Oxygen Sensor is expecting more burnt-fuel to pass by, so more fuel enters the equation. If an engine management computer in involved, there might be some potential here...

RH77

Head temps
 

Another issue that is sure to eventually rear its ugle head is head warpage due to thermal gradient issues. Aluminum heads aren't going to tolerate one cylinder being cold without gaskets failing prematurely.

My thought (although clearly not a DYI) would be to continuousy rotate which cylinders are being "killed". But that would get seriously complex given the mechanical issues.

Now back to thoughts of retrofiting my Gen 2 Camry (wagon) with a plug-in Hybrid ...

Sorry to jack the thread but... I read some folks opinions on removal of connecting rod and pistons for deactivation and wanted to share an experience. My dad who taught me all of his redneck engineering, once made a 2 cylinder VW that lasted over a year only because it was on its last legs to start with. (Case threads were stripped). At any rate, he pulled two pistons out because of a spun bearing on one journal so it would not shake so badly. He used a hose clamp and a strip of beer can around the journal to keep oil pressure to the other journals. The car took almost a half mile to get up to 55mph, but he drove it for over a year before the case studs gave up for good. It ran smoothly, idled fine and got well over 30mpg. Thanks for everyones efforts here...cheers.

snedden -

This is pretty cool. I assume you are talking about a classic Beetle (pre-VW Rabbit). Can you remember which 2 pistons were removed?

Here's a stretch :

VWs are flat-4 air cooled "boxer" motors
Subarus are flat-4 water cooled "boxer" motors

I wonder if there is something in the balance of a flat-four that lends itself to stable cylinder deactivation.

This implies to me that you could :

- Take a classic VW bug
- Remove the body down to the belly pan
- Put on a super-light body shell (dune buggy or ?!?!?)
- Add light-weight bucket seats
- Remove 2 cylinders
=> Have thrifty 2 cylinder VW

Reference - Flat engine
https://en.wikipedia.org/wiki/Flat_engine

CarloSW2

Absolutely. Any buddy pair could be deactivated for balanced operation. That's one of the reasons Subaru has been such an advocate of the boxer motor. They don't have to reinvent the wheel every time they want to add or remove cylinders.

theclencher -

The e-vile petrol manufactures stole it!!!!!!! Why won't you believe me?!?!?!?!?!?! It's cool to know that someone already made it. It's a natural, I guess. I wish the Kit-Car market was still bug-based instead of custom-tubular-chassis-super-expensive-design-based. If it was a Master's thesis, it should be on file in the archives.

This is also why I wish Subaru would offer econobox 2WD cars. They have 4-banger cylinder-deactivation sitting in their lap!!!!!

Regarding lost cars, I have the same problem with the "Ford Gnat" I saw at an LA auto show in the late 70's early 80's. It was designed by Ghia and now that I think of it, was practically a pre-CRX, or a pre-Metro. It was maybe a little bigger than a Fiat 500 and it was super tiny cool. I couldn't even find it at the Russian concept car site you used in other threads.

CarloSW2

What? You don't want to see this of Ferraris and Porsches? ;)

As far as Subaru is concerned, they went to the AWD-only platform in 96 or so. There are definately some pre-96 FWD Imprezas out there that might be worth exploiting.

Snax -

The thought hadn't occurred to me, but whyyyyyyyyy not!?!?!?!?!

I didn't know that. Subaru is so funny. They have their "niche", but if they want an MPG contender, they need a 2WD option. Econo-boxer-engines for the rest of us!!!!!

CarloSW2

Hmmm jumping in here late I guess, but I have a few things to add.

First off, unplugging the injector is just a bad idea all together for your engine. Your valves will still be opening and closing and believe it or not they need fuel to cool down. If you run it long enough like that you are going to burn your valves up.

Displacement on demand will actually stop the valves from moving so they don't burn out. Its also really lame (at least on SUV's) it more or less will only kick on when you coast, if you blow on the gas pedal it will go back into v8.

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.

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

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

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.

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

3VZ-FE cylinder deactivation system advice
 

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

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...

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

That makes it sound like it's a new, novel idea. It was actually used on production vehicles decades ago.
https://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.

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.

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.

IMO it's problems are that it's "noticable" to the luxo cruiser drivers whose cars it has ended up in and "unnoticable" in the EPA gas-brakes-gas-brakes test scheme. Anyone prepared to put up with a minor stumble as it switches in and out, and who will drive at steady highway speeds would benefit from it... NVH scores more than MPG... even in economy cars... look at all the 3cyl and 4 cyl motors that got inertia hogging, HP losing balance shafts, look at the "silencer" in the 2nd gen ford escorts airbox... there are numerous examples...

I shall :p
Getting a good baseline and testing emergency aero mods 1st though. One guy with a minivan same as mine reckons it's good for 35-40mpg on the highway...

IIRC the primary reason for closing valves on deactivated cylinders is so that you are not pumping an excessively lean mixture into the catalytic converter
Satisfy my curiosity on this issue when you are doing injector-kill tests and measure catalytic converter temps with a noncontact thermometer. I would expect the temps to be much higher if youre pumping all that extra oxygen downstream. the only way I could think of getting around it is to have a separate exhaust system for your deactivated cylinders in lieu of disabling valves

That's a possible, might find one of those cutouts if I have issues.

Dodge 5.7 cylinder deactivation
 

Just had a valve drop into the piston braking the rod and stabbing a hole in the block. After taking some time reading this post I thought I would give it a go. Here's what I found, I removed the oil pan and found some parts so thinking about it I noticed deep scratches on the cylinder wall and a stuck piston, it's destroyed right? Wrong wrong wrong. I cut the stub or the smashes rod off and left the rod in place. Then cleaning old pan up and patching the hole in the block with job weld "size of a fist". Then removing passenger valve cover and removing spring and clips from the dropped valve. Then removing both Rockers and push rods on the damaged cylinder. Again plugging the exhaust valve hole with job weld seeing how now that the valve is into the piston. And I left the intake valve alone seeming show it's not going to move anymore. Put the valve cover back on.Next step unplugging injector and coil for the damage cylinder but leaving coil in place to give the stock look. Filled the finely tuned motor with new oil and starting it. Now having more than 5000 miles on it, it's still running just fine and only a very trained ear could notice a slight miss, seeing I have after market muffler it gives it a rumble and sounds good. As for power it's not really noticeable unless you tow a trailer but it has always been doggy. That's my two cents. I have about 40$ into oil filter, oil, and ten tubes of job weld. In short it works and it's a seven cylinder and I did not notice any gas savings or more gas uses it is almost the same.

Best engine repair story, ever.