Injector Shutoff

[slothman86]

I was sitting at school today and wondered what would happen if you could shut one of the injectors so that only 3 cylinders are operating. I dunno. I was really tired and it seemed like a good idea at the time. This could be a way to improve fuel economy even more...LOL. I think its a long shot at best.

Any thoughts?

[bobolinko]

Originally Posted by slothman86

I was sitting at school today and wondered what would happen if you could shut one of the injectors so that only 3 cylinders are operating. I dunno. I was really tired and it seemed like a good idea at the time. This could be a way to improve fuel economy even more...LOL. I think its a long shot at best.

Any thoughts?

Will cause more problems than anything else. The pistons are still going up and down, and the fuel in the cylinder will be expelled as unburnt exhaust gasses...
Stay in school, and get a complete education before you start trying to design automobiles. lol Good "idea" but that won't work for anyone's benefit.

[slothman86]

Originally Posted by bobolinko

Will cause more problems than anything else. The pistons are still going up and down, and the fuel in the cylinder will be expelled as unburnt exhaust gasses...
Stay in school, and get a complete education before you start trying to design automobiles. lol Good "idea" but that won't work for anyone's benefit.

I'm sure it'll cause problems....that's why I said it was a long shot at best, at least for our existing car. I don't think there will be any fuel injected into the cylinder because the injector will be shut off...like this...

http://en.wikipedia.org/wiki/Active_Fuel_Management or this...http://en.wikipedia.org/wiki/Variable_displacement

I was just talking about adapting this existing tech to an existing engine. I just wasn't exactly sure what it was called in the OP.

I'm not sure what you mean, of course the pistons will continue to go up and down. The yaris already has DFCO which is sorta like this.

BTW, this all started because we were talking about this existing tech, and I thought it was a good idea....but instead of deleting half the work load...only one cylinder...

[H3LlIoN]

Originally Posted by bobolinko

Will cause more problems than anything else. The pistons are still going up and down, and the fuel in the cylinder will be expelled as unburnt exhaust gasses...
Stay in school, and get a complete education before you start trying to design automobiles. lol Good "idea" but that won't work for anyone's benefit.

Wow. You clearly have never heard of "Displacement on Demand." Then again, I guess the crazy guys over at Cadillac should have stayed in school. Also, how is fuel in the cylinder going to be expelled as unburnt gas if you shut off the injector? There wouldn't be any fuel to expel. Smooth going, ace.

[H3LlIoN]

Originally Posted by slothman86

...only one cylinder...

One cylinder wouldn't be able to handle it...you have to have enough firing to blow the crank up, then back down. Generally, it takes half of the cylinders to fire. I've had the head off a 1NZ...you could probably make this work by firing 1,3 or 2,4, since 1 and 4 are on the same stroke, and 2,3 match as well. You could test by plugging two injectors. It will throw a CEL but, if it runs at all, you at least know it's feasible. Tuning will be an issue though...you'd have to go standalone and write custom stuff.

[slothman86]

Originally Posted by H3LlIoN

One cylinder wouldn't be able to handle it...you have to have enough firing to blow the crank up, then back down. Generally, it takes half of the cylinders to fire. I've had the head off a 1NZ...you could probably make this work by firing 1,3 or 2,4, since 1 and 4 are on the same stroke, and 2,3 match as well. You could test by plugging two injectors. It will throw a CEL but, if it runs at all, you at least know it's feasible. Tuning will be an issue though...you'd have to go standalone and write custom stuff.

oh no, i mean only starving one cylinder...lol. I have a few pals at school, that have custom piggybacks that they built from scratch. Tomorrow I'll run it by them and see what they think. Thanks. Maybe the o2 sensor would see this and pour even more fuel into the remaining cylinders? Isn't that their job?

[H3LlIoN]

Yeah, that's why you'd have to write new programming. BTW, a custom piggyback and a full standalone aren't the same......A piggyback isn't going to work for what you are talking about. Troll the performance forums a bit for info on tampering with the toyota ecus, it's a PITA. Also, a piggyback is for adjusting fuel, A/F, timing, etc...you are talking about rewriting the program so that it shuts down two cylinders in "cruise mode" and essentially would fire back up @ WOT. This is in production in GM vehicles, and some others too. Not new tech, just complicated to write.

[yaris-me]

The amount of work wouldn't change. You would be asking three cylinders to do the work of four. The same amount of energy if not more would be required, because you have to keep one cylinder turning.

[Loren]

A 4-cylinder engine is balanced to run as a 4-cylinder engine. If you disable one cylinder, the remaining three will not run smoothly. You could DO it, but there's no way you could sell such a car because on 3 cylinders, it wouldn't idle smoothly and it wouldn't run smoothly.

In reality, it would probably take MORE fuel to run a 4-cylinder car on 3 cylinders due to that inherent imbalance which would need to be overcome.

Cutting cylinders works in something like a V8 engine (I think I read that the new Chryslers like the Charger are doing it for economy, so it's not just the historic Cadillac failure) where two or four cylinders can be dropped and still retain a somewhat balanced cycle.

[H3LlIoN]

Originally Posted by Loren

(I think I read that the new Chryslers like the Charger are doing it for economy, so it's not just the historic Cadillac failure)

Yeah, Chrysler, Honda and GM all have some type of this tech in effect and available on new cars.

OP...I was thinking about this last night...for some reason, I seem to recall that it only works on a V style engine. Smallest I can find is V-6.

[127.0.0.1]

it would not work for long without major reprogramming of the
ecu, and all new engine components

you'd immediately code with engine misfire, and be running in disabled mode
VVTi would not engage

to make the engine actually last like a normal Toyota engine:
engine would be out of balance, eventually destroying the crank bearings prematurely
emissions systems would need new components...
you would need a different alternator
you'd need a differently designed transmission

and the list gets longer

don't run a 4 cyl as a 3 cyl, that is wrong. power pulses would
go against the overall design of the 4cyl.

variable displacement engines look good on paper, but are incredibly NOT simple
to build and make them last. refer to GM and the early Cadillacs with variable displacement
and the nightmarish early designs and failures.
"But the system was troublesome and a rash of unpredictable failures led to the technology being quickly retired"

To have variable displacement -work-, you start with an empty engine bay, and design
the entire motor from scratch. you must be able to operate the valvetrain on the 'dead cylinders'
differently than the live ones. merely operating the dead cylinder as a pump will not work
for very long before major damage occurs

[minnyar]

FWIW, I unplugged three plug wires on a rental Taurus once, it drove fine, probably used less gas as well. Would I do this to my own car, HELL NO!

[YarisOwnersDad]

Originally Posted by minnyar

FWIW, I unplugged three plug wires on a rental Taurus once, it drove fine, probably used less gas as well. Would I do this to my own car, HELL NO!

How could it use less gas just because the spark plug wires were disconnected? The fuel would still be going into the cylinders, but it would be unburned and would contribute nothing to the energy to propel the car.

[minnyar]

Originally Posted by YarisOwnersDad

How could it use less gas just because the spark plug wires were disconnected? The fuel would still be going into the cylinders, but it would be unburned and would contribute nothing to the energy to propel the car.

I just assume it would use less gas as the engine would not rev beyond 2000ish rpm. Up to that point it probably uses just as much as normal.

PS: Don't EVER buy a used rental car.

[127.0.0.1]

Originally Posted by minnyar

PS: Don't EVER buy a used rental car.

this.

I have abused the hell out of rentals. positively slamming the transmission
into gears that should not be used in the direction I was headed.

I ain't proud of it...I am just saying I, and others, have done such things.

it's guaranteed that any used rental has had one or more abusers drive it.

[Yaris Hilton]

Shutting off the fuel to one cylinder, while letting it still breathe air, will throw off the mixture feedback from the oxygen sensor. The car will go into "limp mode."

Unplugging spark plug wires while letting fuel flow through wastes fuel. The remaining cylinder has to work harder to make the car go, and the other ones get the increased fuel flow, too.