"variable cylinder shutoff"??

[Mr. Wyndham]

Originally Posted by TAG UR IT

:eek: Yeah...that was a goof up! Sorry bout that...it was a 6 cylinder to 3 cylinder!!! Thanks for pointing that out. And if you're still interested...I rented it at Alamo rental in Cali.

Oh, that's nice Tag, just great...you drove an V8 malibu, and now your lying about it, instead of sharing the experience! Great...you think you know a guy... - had to, sarcasm's my game!

But I like to consider myself very knoledgeable about this particular topic...I don't build them...like some of us ...but I read a lot

MOST OF THIS IS REPEATED, I just love to type, right?:p

It's called AFM, active fuel management. It DID used to be called Displacement on Demand (I like this name better). I seem to have noticed that it's a mostly concentrated feature in Chevrolet engines, other branches have it, I do know that (just not which ones). It shuts off 4 of your cyllinders, either from a V6, or a V8. Got this from chevy.com:

Active Fuel Management™ deactivates four of the six or eight (depending on the engine) cylinders with seamless precision

It's been around for a while (in idea-form just before recently). I was told by someone much older than me, though not a very reliable source, that when it was introduced way back when, that mechanics rejected it - because it was a bite to repair. 8 to 6 to 4, come on, right? Todays setup is much simpler, both overall and because it's only in 2 stages. Most of the reason it's easy is because the ECM (engine control module), or the on-board computer, takes care of it's activation. I've heard from one of GM's sites...actually I think it may have been THE GM site, that said AFM offers significant fuel economy gains, but those who do a extensive highway driving can expect even higher gains. Virtually a 4 cyllinder at 55mph, following me?

This technology is really neat, it works like this, so I understand: when activated, half the engine's valves (those of the AFM cyllinders) are "separated" from the camshaft. There are pressurized "connectors", that allow the pushrods to move without effecting the valves. Stopping intake, and exaust valves from moving, thereby taking a load off the engine (allbeit a small one). The injectors are also shut off (hence the fuel savings). Since the computer controls it, it's activation in measured in 100ths of seconds, seamless - and virtually undectable (except for the instant power thing). The activation is triggered under "light-engine load" though what that is defined as.... I wonder, form those with experince behind the wheel of one of these, does it activate under idle conditions?

The Camaro has been reported by GM as expecting 30 mpg highway, and I've heard 33, too in other reports - so I'm sticking to GM's 30. Though, expect a little more with extensive highway driving.

Silverado's have it, and still make MASSIVE power numbers! so I Like it!

[3whiterag]

Originally Posted by Dragoneye

Oh, that's nice Tag, just great...you drove an V8 malibu, and now your lying about it, instead of sharing the experience! Great...you think you know a guy... - had to, sarcasm's my game!

But I like to consider myself very knoledgeable about this particular topic...I don't build them...like some of us ...but I read a lot

MOST OF THIS IS REPEATED, I just love to type, right?:p

It's called AFM, active fuel management. It DID used to be called Displacement on Demand (I like this name better). I seem to have noticed that it's a mostly concentrated feature in Chevrolet engines, other branches have it, I do know that (just not which ones). It shuts off 4 of your cyllinders, either from a V6, or a V8. Got this from chevy.com:
It's been around for a while (in idea-form just before recently). I was told by someone much older than me, though not a very reliable source, that when it was introduced way back when, that mechanics rejected it - because it was a bite to repair. 8 to 6 to 4, come on, right? Todays setup is much simpler, both overall and because it's only in 2 stages. Most of the reason it's easy is because the ECM (engine control module), or the on-board computer, takes care of it's activation. I've heard from one of GM's sites...actually I think it may have been THE GM site, that said AFM offers significant fuel economy gains, but those who do a extensive highway driving can expect even higher gains. Virtually a 4 cyllinder at 55mph, following me?

This technology is really neat, it works like this, so I understand: when activated, half the engine's valves (those of the AFM cyllinders) are "separated" from the camshaft. There are pressurized "connectors", that allow the pushrods to move without effecting the valves. Stopping intake, and exaust valves from moving, thereby taking a load off the engine (allbeit a small one). The injectors are also shut off (hence the fuel savings). Since the computer controls it, it's activation in measured in 100ths of seconds, seamless - and virtually undectable (except for the instant power thing). The activation is triggered under "light-engine load" though what that is defined as.... I wonder, form those with experince behind the wheel of one of these, does it activate under idle conditions?

The Camaro has been reported by GM as expecting 30 mpg highway, and I've heard 33, too in other reports - so I'm sticking to GM's 30. Though, expect a little more with extensive highway driving.

Silverado's have it, and still make MASSIVE power numbers! so I Like it!

Well Done!!!

[TAG UR IT]

Originally Posted by 3whiterag

Well Done!!!

That's what I was saying! And from a powertrain man himself! Kudos to you, Dragon.

Yes, I drove a Malibu, no it wasn't a V8... Since we talk so much about the V8, it just came out that way. But, I didn't even realize the engine was shutting off 3 of the 6 valves while driving. It was a while after driving that I was messing around with the odo contols to see what all the Malibu had. We were on the 101 doing about 80 or so and it said something like "3 cyl _____" Don't remember what else it was...maybe "off?" But, I'd hit the gas....NO LAG AT ALL....and bam, we were moving again w/out any hesitation. Really, like GM said, it was seamless. You couldn't tell at all.

As for the idling, I couldn't tell you for sure, but I'm 99% positive it will not deactivate the cylinders while idling.

Again, I really liked that write up. It was informative!

[TAG UR IT]

Oh, and it constantly went from 3 to 6 on the hwy. Press the gas and it's 6. Let off the gas and it's back to 3. Tap the gas just a tad harder than you should and it's off again. But, it does work...and it does save gas.

[Mr. Wyndham]

Originally Posted by 3whiterag

Well Done!!!

Originally Posted by TAG UR IT

That's what I was saying! And from a powertrain man himself! Kudos to you, Dragon.

Again, I really liked that write up. It was informative!

Right, and Thanks!!! To you, Tag - and to 3Whiterag (it was an honor coming from a powertrain guy). I do a lot of reading on this stuff, can you tell? I really get facinated with these kinds of things. Again, Thanks!

btw, did I cover it all whiterag?

[Power Junkie]

Umm... now i like the idea of saving fuel, but what about the exhaust note, obviously with all the V8's cylinders pumping away we should get a nice sound but what will happen when 4 shut off??

Will it quieten down or will it keep it's muscle tone??

[CamaroSpike23]

Originally Posted by Power Junkie

Umm... now i like the idea of saving fuel, but what about the exhaust note, obviously with all the V8's cylinders pumping away we should get a nice sound but what will happen when 4 shut off??

Will it quieten down or will it keep it's muscle tone??

i would imagine it would quiet down a tad, but when you are cruisin long distances I would think it better to be quiet. I drove From SC to IL and back a couple times in my 94 with the cutout open and closed and my exhaust is loud as is and after a while it starts to wear on you.

but with the AFM, just drop the hammer and activate all 8!

[Mr. Wyndham]

Right...everything will be effected with only half your cyllinders running. And at the strict parameters that are set for deactivation, I don't think you'll find an exaust note welcome at those times, anyways. I.E. Highway cruising, rolling down a hill, cruising through a city street (no gas).

And if you do want the note...pop it into a higher gear, and hammer it. You'll get all eight back up (That'd be considered a high-load)

AFM is definitely a win/win

[Jak]

Just think of the fun you could have. Everyone knows horses don't like loud noises, you go from very quiet (4 cylinders) coasting through town to a growl (8) and scare the little mustangs into a stamped, when ever your around.

[Justcallme61]

the only thing im not sure about is...how reliable is "AFM" or "DoD"? i mean is it likely that it will eventually stop shutting down cylinders (which i guess isnt a bad thing, hearing that beast all the time ;-) ) or go out like a tranny?


on a side note, i want a camaro.

[Mr. Wyndham]

I shouldn't think so...
there aren't any "moving parts" so-to-speak...it's mostly fluid working it's hydrolic magic.

[Justcallme61]

oh really? yeah i didnt really know how it worked haha. i guess thats good then, awesome!

[Mr. Wyndham]

there are moving parts...I mean, there's a little cyllinder in between the cams and pushrods - from what I understand, and fluid compresses something inside the cyllinders to "connect" the pushrods to the cam...and releases when AFM activates...

The rest: fuel, spark, and valve deactivation signal - are all computer controlled.

[Justcallme61]

i figured it was something like that, but wasnt sure. thanks for clearin it up