Retarded?

[poniesviii]

You know, it wouldn't bee too difficult with our friendly firing order to cut spark and injector to half our cylinders while highway cruising with the cruise set to save some f'n gas with the gas prices.

Anyone have input?

 

[unity]

On a Gen One you could only kill the injectors. I though of this many time, but the car would have to be running on a dyno in real time to see whats going on. Things at idle are never the same with a little load.

The Gen ones wire the spark plugs in series. I though the Gen 2 did also, but from what I was told the EDIS provides 8 true trigger wires. So on a Gen 2 is may be very possible.

It would be interesting to what someone could come up with to balance the firing order right to achieve this. Or for that matter, has someone already?

 

[poniesviii]

I'm glad you responded man.

.. anyways, .. ... but what if the gen 1 is converted to the COP, that's still series?

edit: Series doesn't change the possibility actually. But it could be a cleaner job.

And, the EDIS, easy swap to '96 obd II?

 

[unity]

My Gen 1 is converted to cop. Still in series. If you are in series and bypass a plug the single plug may not fire right, somehow both COPs or coils provide a certain resistance thats critical for proper spark.

But really, I dont think you have to kill the spark plugs. All they will do if fire away with nothing to ignite if you just kill the injectors. Right?

As for an EDIS swap, I am sure if can be done but then you will have to rework the engine harness and umbilical plug. Not hard, just some work.

 

[96hotrodlincoln]

Think about it, if you just killed the spark, you'd still be pumping fuel into the cyclinders, what would happen when you applied spark again, you'd have a bunch of excess fuel in the cylinder or dumping out in the exhaust, it could be quite catastrophic to your motor.

You'd want to kill the injectors!

 

[unity]

Think about it, if you just killed the spark, you'd still be pumping fuel into the cyclinders, what would happen when you applied spark again, you'd have a bunch of excess fuel in the cylinder or dumping out in the exhaust, it could be quite catastrophic to your motor.

You'd want to kill the injectors!

We know that. The original thought was to kill both the injector and spark at the cylinder. I am just not sure if thats needed, killing the injectors only may be easier and it would be the least amont of work. We certainly dont want to kill just the spark! The idea is to save fuel when idling along he highway.

 

[unity]

By the way, this is easy to test.

Anyone have the firing order? I forget.

All we need to do is unplug injectors to see if the right combination can me made to have it run smooth.

I know for a fact though, if I unplug #5 it runs rough. I have a bad harness connector and it slides off pretty easy.

 

[Moes8]

i've considered this too, the only problem beside actually cutting fuel/spark is that having a some cylinders not firing while the engine is spinning away is that those cylinders will be cold and the metal is not at operating temperatures,running an engine or parts of an engine way below normal temps will cause incorrect tolerances and possible premature wear,

this is why on engines made today that deacitvate cylinders,they alternate which cylinders are on or off as the engine runs,you dont want hot spots and cold spots in the engine, like doing this would cause.

but i would love to see someone try it for a little non harmful distance and see what the MPG is !!!

 

[unity]

Never thought of the temp issues, but relatively speaking, would it big a BIG difference with all that ambient heat being transfered? I honestly have not clue, but my first thought is that the entire engine would run cooler.

But that does bring to mind piston head and connecting rod stress. is there any potential damage with the pistons being pulled down instead of pushed. This happens normally but a valve is open. But when combustion is suppose to take place there may be a slight vacuum even after compressing the air?

 

[Moes8]

i also think i read on new deactivating engines,the valves are held open(by way of the variable valve timing system) on the cylinders not firing,
there is a lot going on in those new type engines besides just no psark/fuel

 

[brentalan]

I think the valves are actually held closed. The air is held in the cylinder and used as a sping to push them back down when they have compressed it.

 

[unity]

I think the valves are actually held closed. The air is held in the cylinder and used as a sping to push them back down when they have compressed it.

Thats what normally happens though, right? Compressed, ignite, push down piston. My though was without detonation the cylinder is being more pulled than pushed even with compressed air behind it.

 

[Blenderhead]

The valves are left closed in a displacement on demand system. Basically what they do is they have a solenoid that controls oil pressure to the individual lifters, so when they want to deactivate a cylinder, they cut off that lifter, it collapses, and no air enters or leaves the cylinder. This way it just creates a vacuum in that cylinder when going down, and then the vacuum helps suck the piston back up and since there is no air in the cylinder, there is also no compression, and you waste power generating compression without getting power out of it. If you were to just kill fuel and spark on half the cylinders, you would probably get worse gas mileage than leaving it running on all 8, cause now you are just putting more load on those other cylinders because they now have to do the work that the others were doing.

 

[crownvicjim]

If you were to just kill fuel and spark on half the cylinders, you would probably get worse gas mileage than leaving it running on all 8, cause now you are just putting more load on those other cylinders because they now have to do the work that the others were doing.[/QUOTE

then how to these other cars get better gas mileage? you still have the same load and "they" make it work.

 

[Blenderhead]

Read the entire post. The other cars keep the valves shut. This means they don't have to compress any air. Have you ever tried spinning over a motor with no spark plugs in it, then put the plugs in and spin it over? When you don't have to compress any air, it takes very little force to spin the engine over. When you need to compress air however, it suddenly takes a lot more effort. If you were to leave the valves working properly and just cut spark and fuel (or even just fuel would work the same) then all you have effectively done is create a misfire. That means that work is going into sucking the air in and compressing it, but you aren't getting any work out of it. Translation: energy and fuel wasted on just keeping the engine running, let along trying to move anywhere. If you have ever driven a car that is misfiring on one cylinder, you would know that power and gas mileage both go to hell. Now how bad do you think its going to be when its misfiring on half the cylinders? In vehicles that have this system from the factory, they also disable the valves. This means no air gets sucked into the cylinder. This means that there is no force required to compress the air that isn't in the cylinder, which means the only amount of wasted energy is equivalent to what it takes turn a motor over with no spark plugs in it.

 

[unity]

Would oil then not get sucked up past the rings on the downstroke?

 

[Moes8]

I think the valves are actually held closed. The air is held in the cylinder and used as a sping to push them back down when they have compressed it.

thank you,i had it backwards

 

[Blenderhead]

Would oil then not get sucked up past the rings on the downstroke?

Some oil will get on the cylinder walls, however it will be scraped off by the oil control rings same as normal. However the way piston rings work, the pressure of compression is channeled behind them to push them against the cylinder walls, which makes them seal much better. So without any pressure pushing them out, they don't seal as well, and therefore don't produce enough vacuum to suck the oil out of the pan.

 

[poniesviii]

Read the entire post. The other cars keep the valves shut. This means they don't have to compress any air. Have you ever tried spinning over a motor with no spark plugs in it, then put the plugs in and spin it over? When you don't have to compress any air, it takes very little force to spin the engine over. When you need to compress air however, it suddenly takes a lot more effort. If you were to leave the valves working properly and just cut spark and fuel (or even just fuel would work the same) then all you have effectively done is create a misfire. That means that work is going into sucking the air in and compressing it, but you aren't getting any work out of it. Translation: energy and fuel wasted on just keeping the engine running, let along trying to move anywhere. If you have ever driven a car that is misfiring on one cylinder, you would know that power and gas mileage both go to hell. Now how bad do you think its going to be when its misfiring on half the cylinders? In vehicles that have this system from the factory, they also disable the valves. This means no air gets sucked into the cylinder. This means that there is no force required to compress the air that isn't in the cylinder, which means the only amount of wasted energy is equivalent to what it takes turn a motor over with no spark plugs in it.

I don't necessarily agree with the misfire theory, because when an engine's misfiring, it's because timing is off, -or, spark is way too weak to fire on every cycle. In short, the fuel mixture is getting FIRED at a MIS opportune moment. So, we wouldn't have that problem, or the bad mileage or a poor running engine because of that. simply because we wouldn't have fuel in that cylinder. misfire-impossible.

Your trapped air theory.. It could create alot of suction. However, I bet compressed air will expand without much effort. I could be wrong, but, have you ever used a portable air tank or air compressor? I understand it's alot faster process in the cylinder, but my theory's feasable eh?

The only extra work I can see the engine doing.. is on the intake stroke for the dead cylinders. Sucking air,,.. what would be the air fuel mixture- in, in prep for the compression stroke. but, with valves open it's still not much extra work. We're talking cruising down the highway, cruise set, in an aerodynamic car that's using maybe 100 horse to hold highway speed.

Anybody else? My car's down with the tranny and driveshaft out. I wish I could test this today.

Thanks for the responses..

 

[Moes8]

I don't necessarily agree with the misfire theory, because when an engine's misfiring, it's because timing is off, -or, spark is way too weak to fire on every cycle. In short, the fuel mixture is getting FIRED at a MIS opportune moment. So, we wouldn't have that problem, or the bad mileage or a poor running engine because of that. simply because we wouldn't have fuel in that cylinder. misfire-impossible.

Your trapped air theory.. It could create alot of suction. However, I bet compressed air will expand without much effort. I could be wrong, but, have you ever used a portable air tank or air compressor? I understand it's alot faster process in the cylinder, but my theory's feasable eh?

The only extra work I can see the engine doing.. is on the intake stroke for the dead cylinders. Sucking air,,.. what would be the air fuel mixture- in, in prep for the compression stroke. but, with valves open it's still not much extra work. We're talking cruising down the highway, cruise set, in an aerodynamic car that's using maybe 100 horse to hold highway speed.

Anybody else? My car's down with the tranny and driveshaft out. I wish I could test this today.

Thanks for the responses..

just an FYi, i read somewhere it takes 8-10 hp to maintain 60 mph in an average modern car weighing roughly 3000 lbs

 

[Blenderhead]

The valves aren't held opened. They are held closed. And you don't need fuel to have a misfire. Ever have a dead injector? Or a collapsed intake lifter? Both of those things will prevent fuel from entering the combustion chamber, and will create a misfire. The definition of a misfire is not firing at the wrong time, but when a problem prevents that cylinder from making power after it has used energy to compress air. If the valves are held closed, then there is no air to compress, and the piston rings will not seal well, so it will take hardly any work to turn that cylinder over. If you leave the valves operating as normal, but cut fuel and spark from a cylinder, you still have to do all the work to keep 8 cylinders running, only now instead of getting some of that work back from each of the 8 cylinders, you are only getting some of it back from 4. The result is that it is less efficient, and will get you worse gas mileage. If you don't believe me, try it yourself. Unplug half your injectors, leaving 2 pairs of cylinders that are 180 crankshaft degrees from each other, and try driving it around like that and see how many miles a tank of gas lasts. Plain and simple, it doesn't work without the valvetrain mods. If you can figure out a way to disable the valves at the same time as the injectors, then you can make it work, but that is far more complicated than just disabling injectors, and without it you will only hurt your mileage.

 

[chicken]

The valves aren't held opened. They are held closed. And you don't need fuel to have a misfire. Ever have a dead injector? Or a collapsed intake lifter? Both of those things will prevent fuel from entering the combustion chamber, and will create a misfire. The definition of a misfire is not firing at the wrong time, but when a problem prevents that cylinder from making power after it has used energy to compress air. If the valves are held closed, then there is no air to compress, and the piston rings will not seal well, so it will take hardly any work to turn that cylinder over. If you leave the valves operating as normal, but cut fuel and spark from a cylinder, you still have to do all the work to keep 8 cylinders running, only now instead of getting some of that work back from each of the 8 cylinders, you are only getting some of it back from 4. The result is that it is less efficient, and will get you worse gas mileage. If you don't believe me, try it yourself. Unplug half your injectors, leaving 2 pairs of cylinders that are 180 crankshaft degrees from each other, and try driving it around like that and see how many miles a tank of gas lasts. Plain and simple, it doesn't work without the valvetrain mods. If you can figure out a way to disable the valves at the same time as the injectors, then you can make it work, but that is far more complicated than just disabling injectors, and without it you will only hurt your mileage.

i totally agree, hell just try keeping your car running with half of the cylinders unplugged, unless you have some way of disabling the valve train for the disabled cylinders, i think this theory is mute, it gets tossed around every couple years

 

[MediumD]

AFAIK, when switching to 4 or 6cyl mode, the valves on the cyls that are being deactivated are switched to always-closed after the intake stroke... So the compression stroke occurs, and the compressed air acts kind of like a spring and pushes down on the piston during what would normally be the combustion stroke. So a strong vacuum never occurs in the cylinder...

 

[unity]

AFAIK, when switching to 4 or 6cyl mode, the valves on the cyls that are being deactivated are switched to always-closed after the intake stroke... So the compression stroke occurs, and the compressed air acts kind of like a spring and pushes down on the piston during what would normally be the combustion stroke. So a strong vacuum never occurs in the cylinder...

The valves are closed on combustion. Intake in, compress & combust thrust down piston head, exhaust valve open on upthrust followed right away by intake valves opening at top.

 

[poniesviii]

Well, I'll try it anyways. It'll be awhile until the car's back together but I'll post with results.

3-7-2-6 Would be a balanced firing order, but it'd be a paused firing order, with possibly too large of pause. I'll try that though, and if it idles [healthy] I'll take it onto the interstate then cut the inj's off to all but those cyl's and see what mileage reporting is on the puter. It shouldn't lie.

I'll also try cutting only two cyl's, the two I select to cut due to our firing layout will be 3 & 5. So my firing order will be 1-7-2-6-4-8.

We'll see if all that extra power it's gonna take to turn the dead cylinders makes the live cylinders fight more than normal to pull the car down the interstate. I doubt they'll be worked any harder than normal, while cruise is set, but I can see it going either way.

We'll see.