Dynamic Cylinder Deactivation

[Piwoslaw]

Originally Posted by euromodder

VW will be introducing dynamic cylinder deactivation on their new direct injection 1.4L TSi.
According to VW, their 2 cylinder mode is active in 70% of the NEDC cycle, so expect some seriously improved fuel economy - at least the oficial numbers will look better.

http://www.youtube.com/watch?v=yxjGTBF-dVY

[Piwoslaw]

I there was an article on VW's cylinder deactivating TSI in a magazine (Serwis motoryzacyjny, 11/2011) and it had the following BSFC graph, illustrating an example of how cylinder deactivation can help reduce fuel consumption:


The red line '1' graphs constant engine power, in this example 30kW. By going to an rpm and load closer to the BSFC sweetspot the fuel consumption can be lowered by 20%. Deactivating half of the cylinders helps to increase the load, but among the things the article didn't state are:

• Is that BSFC for the engine in 4-, or 2-cylinder mode? Or maybe combined?
• What would be the effect of only shifting gears?
• What would be the effect of only deactivating 2 cylinders?

Anyhow, the article claimed that only deactivating the cylinders reduced fuel consumption by 0.4 l/100km in the NEDC cycle, while with the Start/Stop system 0.6 l/100km. At steady, low speeds and loads the fc can be reduced by 0.7-1.0 l/100km. The cylinders are deactivated when engine speed is between 1400 and 4000 rpm, and torque between 25 and 75 Nm (the max torque is 250 Nm).

[pete c]

Very interesting thread.

Does it work?

Dunno. I'm not nearly smart enough to know.

Here's what I do know.

This guy is long on claims and sort on demonstrated proof.

It is a very simple concept and I am certain that car makers have played with it. it is much simpler and cheaper than mechanical valve deactivation, but none have brought it to market. My guess is they have found out that either it doesn't save fuel, won't pass emissions or eats cats. The last few posts in this thread mention that vw may have changed this. We shall see.

As for comparing it to limp home mode as GM introduced with the northstar V-8 quite a few years back, I am not sure this is a valid comparison. Remember the purpose of that system was to get you home in the event of a cooling system failure, not to save fuel. I would assume that such a system would run in a rich condition to assist in keeping things from melting down.

Personally, I like the idea. I hope it does work. DCD does work, but it complicates an engine quite a bit. And I abhor complication, unless it provides a considerable return.

[reb01501]

I'm confused. If this is snake oil, why isn't it in the Unicorn section? Can no one agree that it is or isn't possible?

[Ecky]

Forgive me for my ignorance, but was the o2 sensor issue ever addressed? It would seem that this could work perfectly on OBD-1 and older vehicles, and on OBD-2 vehicles as long as the knock sensor doesn't pick it up, but wouldn't the computer still flip out over the o2 in exhaust? Might still be worth it if your open loop maps were good, but it's very far from a good implementation.

[shovel]

I just stumbled on this thread and got to about page 7 before getting bored of the negativity being thrown at this guy.

We're his intended market, and he's trying to make something commercially viable and he was all but attacked over it.

I think a product like this should work - not as well as an OEM solution that addresses the valve opening/closing, but still it should work quite well. Perhaps I misread something but I don't see how this would put the engine in open loop mode, if the engine's ECU believes it fired the injector, and the DCD box takes input from the wideband o2 sensor, compares it against the number of deactivations it knows it made, and produces a voltage the ECU was expecting from its ordinary o2 sensor... then what's the problem? Sounds like a closed feedback loop to me.

I hope this product gets made, and I may just buy one if/when it's available for my car.

[Frank Lee]

You need to keep going past pg 7.

[t vago]

Originally Posted by shovel

I just stumbled on this thread and got to about page 7 before getting bored of the negativity being thrown at this guy.

We're his intended market, and he's trying to make something commercially viable and he was all but attacked over it.

I think a product like this should work - not as well as an OEM solution that addresses the valve opening/closing, but still it should work quite well. Perhaps I misread something but I don't see how this would put the engine in open loop mode, if the engine's ECU believes it fired the injector, and the DCD box takes input from the wideband o2 sensor, compares it against the number of deactivations it knows it made, and produces a voltage the ECU was expecting from its ordinary o2 sensor... then what's the problem? Sounds like a closed feedback loop to me.

It all sounds so wonderfully simple in theory, doesn't it?

Tell me something - if it's so wonderfully simple to deactivate ignition and fuel to individual cylinders, without also deactivating the associated intake and exhaust valves, then why haven't any of the major automakers done it yet? Points will be deducted for invoking conspiracy theories.

Bonus question - How will hee-hee-tech's gadget not interfere with the stock engine computer's hunting algorithm that it uses to determine whether or not the car's catalytic converter is operating properly?

Another bonus - Why doesn't hee-hee-tech still not have any demonstrated product, 4 years after he first announce it to the world?

[shovel]

Originally Posted by t vago

It all sounds so wonderfully simple in theory, doesn't it?

Well, kinda, yeah. Like the E85 kit I installed on my blazer a few years ago just intercepts the injector signal, extends its duration a bit, and lets the car's ECU make up the difference. Dead simple in theory, and whaddayaknow? It just plain works. I understand that DCD isn't exactly the same as enriching to compensate for an oxygenated fuel but it's not so drastically different either.

Originally Posted by t vago

Tell me something - if it's so wonderfully simple to deactivate ignition and fuel to individual cylinders, without also deactivating the associated intake and exhaust valves, then why haven't any of the major automakers done it yet? Points will be deducted for invoking conspiracy theories.

My employer manufactures a lot of electronics, and our engineers come up with all sorts of neat features we could add to them. In the end, we don't really add most of the features our engineers come up with. Sometimes we leave a feature off a $1000 product because it would add four cents to the manufacturing cost. Sometimes we leave features off because we think they might increase warranty claims due to consumer incompetence, or because there are some circumstances where that feature pushes the product too close to a failure limit. Sometimes we leave features off because we run out of time to properly test and implement them in the final revision cycle. It's not a conspiracy to make worse products, it's just how product development goes.

My guess is, the engineers who have the luxury of designing a vehicle system like cylinder deactivation at the OEM stage can design a complete system which includes the valve deactivation, and since they can, they do. If you're going to call that a conspiracy theory... well, rock on dood. I'm not here for "points"

Originally Posted by t vago

Bonus question - How will hee-hee-tech's gadget not interfere with the stock engine computer's hunting algorithm that it uses to determine whether or not the car's catalytic converter is operating properly?

Beats me, what makes you think this is impossible? The stock ECU's expecting a signal, you give it a signal, it's happy. People spoof devices and translate data all the time. I spoofed my jeep radio to think it still has a CD changer so I could hijack the cd changer input for mp3.. machines are just machines.

Originally Posted by t vago

Another bonus - Why doesn't hee-hee-tech still not have any demonstrated product, 4 years after he first announce it to the world?

Business is rough like that, where's your product? I tried to open up a coffee shop when I was 18, and now it's not in business anymore - doesn't make me an a-hole.

What's your beef, anyway?

[Heihetech]

Originally Posted by shovel

Well, kinda, yeah. Like the E85 kit I installed on my blazer a few years ago just intercepts the injector signal, extends its duration a bit, and lets the car's ECU make up the difference. Dead simple in theory, and whaddayaknow? It just plain works. I understand that DCD isn't exactly the same as enriching to compensate for an oxygenated fuel but it's not so drastically different either.

Shovel,
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ones that believes traditional, outdated solution than DCD.
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