1987 voyager with displacement on demand...

[mightymulhern]

Actually that sounds like the AIS is opening to introduce more air (more air blowing through it would be the whistle). That would be the equivalent of opening the throttle slightly or the accelerator dipping to the floor when your speed is too slow for the engine to keep up.

Running lean would make the exhaust hotter. Running rich, cooler. I was theorizing that your ECU would "think" you were running lean and intruce more fuel so you are really running rich. ...again this is just a best guess.

Supposedly engines are the most efficient running all out at their torque peak which jives with what your'e suggesting about 70mph just being about perfect (ie just enough for the engine to maintain speed). On a 5spd you could probably do the same in 4th gear at 55/60.

Moving the O2 to another location would be relatively easy. Holding an exhaust valve open continually... substantially more difficult. In any case, great idea. If you use the numbers you suggest 26 and 35, and assume gas at $3.25/gallon (chicago), you're looking at a saving of $32 per 1000 miles which isn't that much in the context of a road trip but would really add up over the course of a year for someone with a long daily commute. Well done!

[Phatfoto]

If you could rig it to switch over to 3 cylinders when the ECM locks the torque converter, that would be cool. Back to six when you step on the throttle enough to unlock the TC...

[sgt. minivan]

yeah im the same person that was on allpar. adam delp

[lookin]

Quote:

Originally Posted by Ondonti anyone know the effects of not having combustion in 3 cylinders long term? increase cylinder wear? scuffing? what? Anyways, you need 1 whole bank firing (obviously you know this) otherwise the engine shakes like crazy because its imbalanced. I drove my spirit once 50 miles on cylinders 1 2 and 4. Not good. Ive done a lot of idle testing with 1 2 and 3 cylinders on my duster though with all my fouling problems.

I think the unfired cylinders would have less ring seal, since they would not be pressurized to then fully expand, and so cylinder wear 'may' even decrease since they would still be getting oil. Then again, those unfired pistons would be sloppy in the cylinders, and scuffing may very likely result. I dunno. Maybe not.

[lookin]

Quote:

Originally Posted by ShelbyDodgeImp Are you the same guy who was doing DOD who was posting on Allpar for a while back or are there TWO of these vans running DOD these days? As to gender and cars, you'd be pretty surprised how many girls are on some of these boards. I know a few who don't really make it known that they're girls because of the attention (not all of which is good) that it can generate. There was a girl on DI.net that basically stopped posting because she kept getting crap about her car, people saying it isn't a "girl's car" and she needed to get something that wasn't a "guy's car" Generally speaking its not as bad on these boards as some of the military related boards out there... the more stereotypically male you get the more problems there are probably going to be, if I were to venture a guess. Its a field wide problem to be honest, my roommate used to be a mechanic but had to leave the field work/career wise because every job she got, no matter what shop it was, either tried to push her into secretary work or- when that wasn't a problem, parts suppliers kept thinking since she was a girl they could pull whatever tricks they wanted on her. Now she does metal fabrication and only does cars as a hobby, no matter how much past shops want to grab her back (especially with the fabrication expierence now).

You said a mouthful. All very true. I usually keep my gender a secret on the net, but the cat was already semi out of the bag here anyways. I am not a feminazi by any means, and yet the sad truth is that we really are pigeonholed and stereotyped by 'some' men. If we don't like that, and say so, then some jerks accuse us of wanting to be men. There are plenty of good men out there though, and there is no shortage of less than good women also. Sexism is not the answer to sexism, and men are not the problem, sexism is.

The reason I got into cars, is because I got tired of being ripped off by mechanics. I always found out in hindsight, when guy friends would say stuff to me like, they charged you how much ..... for a what?!!! Honey, .... there is no such part on your car, and this part is something they just made up! .... So I began to learn. Then about 5 years ago, I asked on the internet how I could pep up my 3.0 Caravan, because it was a total dog, and now I am totally into it and completely hooked for life.

[lookin]

Quote:

Originally Posted by sgt. minivan yeah im the same person that was on allpar. adam delp

Are you ever. .... and see how well you fit in here? No worries.

[Ondonti]

Quote:

Originally Posted by lookin I think the unfired cylinders would have less ring seal, since they would not be pressurized to then fully expand, and so cylinder wear 'may' even decrease since they would still be getting oil. Then again, those unfired pistons would be sloppy in the cylinders, and scuffing may very likely result. I dunno. Maybe not.

So the one real problem I see is combustion helps clean oil off the cylinder walls.

Anyways this sounds like it would be very effective for 5 speed cars.

BTW, 3 cylinders not getting any fuel wont make a difference in how your o2 sensor reads.
o2 sensors measure the amount of unburned hydrocarbons NOT AIR. The engine has no idea what you are doing. Now, if the fuel injectors were still firing but you werent getting spark, thats a different story.

The engine rpm is dropping because it loses momentum when 3 cylinders stop pushing on the crank. The AIS opens up a little bit to get more air into 3 cylinders and keep idle reasonable.

[c2xejk]

I am curious how you performed the mpg estimate?

Quote:

Originally Posted by sgt. minivan il sure all of you are raising eyebrows at me thinking wtf is this guys major malfunction, well il tell you what, at 70mph im getting ~ 35mpg, where as i only get 26 normally,

[sgt. minivan]

Quote:

Originally Posted by c2xejk I am curious how you performed the mpg estimate?

26mpg has been obtained after i did the wieght reductions and some mods, it was only 21mpg stock hwy 26 is a great baseline since back when i lived in illionis i travled 40 miles one way all hwy to work and 40 miles back, also i made a few trips here to ky (300mile one way) and recorded it at 26mpg, it was very consistant, then after i wired up that switch, i took it on two 60(one way) mile trips, and both times i got between 34 and 36 mpg consistantly, i filled up 4 times, so thats only 240 miles and 4 fill ups logged so far... but you cant hide a gain of almost 10mpg.

[Ondonti]

Talking to a real smart DSM guy (mechanical engineer to) and rear DoD systems switch cylinders every time you move the throttle position and every few thousand rotations.

It would probably be best to have both banks wired to switches so you can not aways rely on the front or rear bank but can switch.

[the machine]

the other bank not getting any fuel will eventually cause valve seat wear/valve guide wear and ring wear, not to mention plug fouling after oil gets past the rings, this is where the caddiliacs failed in the 80's,

the way to do it is to wire both banks to direct current switch (1 switch, one wire), and then wire a different series of switches that directs the power through a set of blinker solinoids(2), seperate switches and powerlines so they dont pulse at the same time, just flip one a second before the other.

i was going to try something like it on my grand prix but it shit the trans out befor i could fix the headgasket leak.

[Ondonti]

Not understanding valve seat/guide wear or ring wear.

Plug fouling yes.

The others dont sound plausible at all. Lets hear the reasons. Combustion has nothing to do with valve guides or valve seats (except that the exaust valve seat removes heat from the exhaust valve which doesnt matter when the cylinder is not firing).

Lack of combustion pressure will mean the rings are not pressing against the cylinder walls with any pressure except innate ring tension that already pushes against the cylinder walls.

Cylinder glazing is a problem that can happen in a poorly broken in engine but in an engine that already has decent ring seal I dont think this would happen.

[87GLHS465]

Quote:

Originally Posted by Ondonti BTW, 3 cylinders not getting any fuel wont make a difference in how your o2 sensor reads. o2 sensors measure the amount of unburned hydrocarbons NOT AIR. The engine has no idea what you are doing. Now, if the fuel injectors were still firing but you werent getting spark, thats a different story.

sounds like someone needs to learn how an O2 sensor works

[Boogieman142]

Quote:

Originally Posted by Ondonti BTW, 3 cylinders not getting any fuel wont make a difference in how your o2 sensor reads. o2 sensors measure the amount of unburned hydrocarbons NOT AIR. The engine has no idea what you are doing. Now, if the fuel injectors were still firing but you werent getting spark, thats a different story.

Sorry brent gotta disagree with ya on that one, they are called oxygen sensors because they measure oxygen content in the exhaust as compared to its ambient air reference. it will see lots of o2 in the exhaust and will think lean so it will richen it up to what the tables "allow" it to do so. so the 3 cyls that are running will run extremely rich and foul plugs, carbon up cyls etc... The other 3 i would think would suffer from increased wear as the pressures from cumbustion/heat help to rid of deposits in there. the fuel going in there helps to cool the valves/seats as well as the top of the piston but then again there is no combustion so there won't be as much heat in there. And the 'working' 3 will be dragging the non working 3 thru all cycles so they would hafta work harder. i think it would be good if fuel, spark were shut off and the valves held a crack opes to dispose of compression. they would hafta alter open, during compression and exhaust open the exhaust during intake and power open intake but all of that isn's really feasable on our engine but if you can make it work more power to ya.

BTW, my last tank of gas - 38mpg

[Boogieman142]

beat me to it i see...