2002/Black/SS

iTrader: (3)

because i standalone can control each injector seperatly, could u make it so half wont spray fuel at certain times, therefore making it like the new multidisplacement HEMIs etc? seems like it would work

njn63

you'd still have the cylinders trying to compress the air which would be an insane amount of wasted power. The DOD motors also have things that change in the valvetrain to keep the valves open (i think, someone correct me if i'm wrong).

GOaT Cheese

They have hydraulically unlocking lifters that stay closed during DOD opperation. I just went through training on that sytem a couple months ago, very elloborate oiling and control system.

Kenova

iTrader: (4)

This way, all of the effort the engine puts into compressing the air in the cylinder is returned on the down stroke. Think of it as having an air spring inside the cylinder.
Ken

njn63

interesting, i was trying to figure out why that was a good idea but that's a good way of putting it.

BigMikeGXP

The newer GM E40 computer runs DoD on a few vehicles. It is pretty much the same computer as in the GTOs, Trailblazer SS, C6 Vette... except it is disabled from the factory in those vehicles. They are going to start using it on more vehicles in the near future.

The mechanical system of DoD is fairly simple. Just ground 4 solenoids and kill 4 injectors and you are running on 4 cylinders. However the timing that goes into activating it is somewhat complex.

Scroll about a 1/3 of the way down this page.

ArcticZ28

iTrader: (14)

Wouldn't this technology cause decreased life of the springs and lifters by keeping constant pressure on them and holding them closed for extended periods of time? Or am I misunderstanding this?

treyZ28

you'll have to worry about your O2 sensors thinking you're ultra rich as well

GOaT Cheese

You don't have any idea how the system works do you? The lifters on four cylinders are hydraulically deactivated so the valves don't open at all during DoD opperation. And if you were to ground the injector drivers, the injectors would stay open and fill the runners with gasoline. The injectors on the deactivated cylinders simply aren't comanded to fire during DoD.

GOaT Cheese

GM is a little smarter than that. They have the system pretty well dialed.

BigMikeGXP

Ummmm.... nobody said anything about grounding the 4 injectors.

The page I linked to goes into great detail how the system works.

There is less stress on the valvetrain components while DoD is engaged. Also the computer will go back to 8 cylinder mode for at least 1 minute if DoD is active for over 10 minutes.


The O2 levels stay the same... They don't get skewed since the 4 cylinders are not pumping.

GOaT Cheese

You are right, I appologize, I completely misread your post. My bad, I'm always so ready to blast people here that I see what I want some times. Next time I will make sure I read more better.

BigMikeGXP

I thought about blasting back... but i figured you just misread. No problem... i do the same thing on a regular basis.