disconnet injectors for fuel savings?

[mr.b]

disconnect injectors for fuel savings?

what if you disconnected 2 or 4 injectors and closed the gap on the spark plug? Could this work as the drop on demand like chrysler or other engines out there? tell me some pros and cons. Just thinking about this on the way home as I rode by a gas station with 3.60 a gallon gas.

 

[Jeff7477]

Doubt it. The computer would probably try to compensate for it by dumping more fuel into the other cylinders.

 

[Mustang5L5]

you'd be lucky if the engine ran

 

[HISSIN50]

Those motors use a complicated design and processing to make this happen. The absolute best someone could do would not be unlike the systems used in the 80's, which left a lot to be desired.

I would toss a vac gauge in the car and never let it dip below 15" (assuming 20" HG at idle).

When I lived in Germany, the stop lights would turn yellow before turning green. This allowed everyone to turn off their cars while waiting at lights.

 

[90mustangGT]

Wow in germany I bet they change starters at service intervals. Not a bad idea, it would stop people from sitting under green lights as much. If things were my way, we would all have light trees at intersections and staging lights. I can't stand when people sit way behind the line not tripping the sensors and when they sit there for three seconds. After the light turned green, if the RT was more than 1.5 seconds, the lisence plate would be photographed and a ticket would be sent in the mail for "poor R/T". Failure to stage and you have to sit until the next light!

No, disconnecting injectors will not work. Your motor would still have to make compression which would take energy. Then the firing cylinders would have to make up for it. The O2 sensors would read lean and would then dump fuel. Those engines that cut injectors also as well cut off the valves so compression is not made. They also alternate cylinders I belive. Not to mention you would have one very hot cylinder and some cold cylinders, might end up warping something. If you want gas milege, sell the car and get something else, or keep it and get a different D/D.

 

[txstang84]

not to mention that removing fuel from any cylinder would make it a "dead" cylinder, and make it run like s***...

 

[srothfuss]

You would use more gas by doing that...

To save gas try slowing down.

 

[bseries4life]

what if you not only disconnected the injectors, but also pulled the spark plugs out of the same cylinders? This would cause those cylinders to move freely w/o compression, wouldn't it?

Someone should try this

 

[J_Squared]

lol, i try not to do more than 1/4 throttle at all times, seems to help a bit, get an extra mpg or so. kinda a pain going up hills though, grrr. yea u would def hurt something by cutting off the fuel at the injectors, EEEVILLL!

 

[vristang]

If I remember right the Chrysler motor seals the chambers. The intake valves are a huge restriction to efficiency. Air being pulled past the valves creates a large amount of drag on the pistons. Also, the air that is compressed in the cylinder returns the energy lost, almost completely, when it expands.

Do not try to do this by unplugging an injector, and definitely don't pull a spark plug. The motor will barely run if at all. You will not get the desired result in increased efficiency. The computer will only see that there is only enough fuel going to each bank for 2 cyl (via the O2 sensor), and further enrich the 2 cyl that are running. I would assume that the computer would then see that duty cycles for the 2 running cyl were doubled (in reality they would hit 100%, since they probably run at 80-85% now), and completely freak out. Codes would be thrown, and even if mechanically the car could run, the electronics may prevent it.

Pulling the plug out will be just as bad. Even if the computer doesn't flip out, you will be loosing a great deal of efficiency by pumping air through the small spark plug hole, on both the compression and exhaust strokes.
The details of this system are a little fuzzy right now, I will have to read up on it again. I'll post when I find the article.

I like that you guys are thinking outside the box, but this won't work without some trick electronics, and a fair amount of mechanical planning.

Anyone know if the chrysler motor is still available? Last I heard it was not selling near as well as expected.

 

[vristang]

lol, i try not to do more than 1/4 throttle at all times, seems to help a bit, get an extra mpg or so. kinda a pain going up hills though, grrr. yea u would def hurt something by cutting off the fuel at the injectors, EEEVILLL!

In theory you should get best efficiency with about 3/4 throttle. You want to get the TB as open as you can without triggering WOT. The throttle plate is a restriction (that is how it works to limit engine speed), and thus hurts efficiency. This is part of the reason diesels are more efficient. 1/2 to 3/4 should do you better than 1/4. Just don't get to wot, where the computer enrichens for max power.

 

[blackstangt]

this gas price thing is rediculous, it's not that bad, in the mid nineties it was like 1.50, now its about 3 after some really bad crap has happened, and people make a lot more money now, cars are more efficient, and money can be saved elsewhere. If people were to stop buying unhealthy mcdonalds or starbucks coffee, they could make up the difference and become skinnier, making it possible to get better gas mileage out of their cars at the same time. but seriously, If you could afford a drop in gas mileage by making your car faster with gears, you can afford it now. I don't want to have to explain that my car is capable of 25mpg everytime I see someone who knows i drive a stang. I have 3.08's and a .64 fifth. I raced twice tonight and passed by the gas station by my house with only a gallon or two less gas, a few dollars isn't going to stop me from enjoying my car as much, with the money i put into it, i better get maximum useage out of it.

 

[mr.b]

I was reading on Chevy’s displacement on demand. They drop 4 cylinders (disable injectors) and they have special lifters that prevent the valve from opening. They said the drive by wire allows this to happen smoothly because it bumps throttle open more so you want notice the drop in power, then it adjusts it back down. Said their fuel efficiency went from 30mpg to 35mpg on the vehicle they used it on. And this motor made 300 hp. It said their V6 made 240hp and had DOD. They would be using it to replace the supercharged Pontiac motor. One added note, they said there was an exhaust butter fly valve that would activate on DOD to adjust the exhaust quieter so you wouldn't notice the cylinder dropping (different exhaust note). Their whole goal is to have DOD and the driver not be able to tell when it happened. Don't get me wrong, I am not a Chevy worshiper, it's just this is the only good article I could find and was really impressed with the technology.

 

[Daggar]

In addition to what mr.b posted, the crank on motors like that one are cut to operate smoothly when running on a reduced number of cylinders. Our cranks are not designed that way. Drop a couple of cylinders on a 5oh and you might as well plan to drive with a tooth guard in place.

 

[mr.b]

i guess what is the most upsetting is this technology is nothing new. And all these domestic car makers could be having alot more sales with better gas mileage from their vehicles while still having the brute power we all love. Just look at the hybrid market, toyota and honda have the most their also. So i am sure they are not seeing any sales drop for those vehicles. I know ford has at least one hybrid (the escape) but they have nothing that gets 60 or 70 mpg like the others.

Just venting!
this 3 dollar gas pisses me off

 

[txstang84]

In theory you should get best efficiency with about 3/4 throttle. You want to get the TB as open as you can without triggering WOT. The throttle plate is a restriction (that is how it works to limit engine speed), and thus hurts efficiency. This is part of the reason diesels are more efficient. 1/2 to 3/4 should do you better than 1/4. Just don't get to wot, where the computer enrichens for max power.

whoa, hold up a sec...if you drive at 75% throttle then you get better efficiency?..in theory? lets think about this, at that throttle setting, you'll be revving up fairly quick, yeah, you might not hit full rich calibration for WOT, but you'll still be running alot of fuel through the system...

I subscribe much more to the practice of accelerating lightly, and shifting sooner (like around 2000-2500). with a carbed car, this practice works like a champ, and i'm very prone to believe that if it works with a carb, then it should work even better with FI. 1EVIL88VERT is running 4.10's in his car with a 302 and your typical assortment of boltons (H/C/I, cai, MAF, TB etc)...he managed 24mpg in town with his car...that says alot to me for someone who's probably pushing close to 300 at the wheels...

another option is to have a tweecer program that runs the car a little leaner, then you can switch back to performance tune when you need to wax those pesky f-body pukes...

 

[Euphoric306]

yea, txstang is right... the throttle plate is a restriction, yes, but it restricts air going into the system which makes more fuel go into the system... restrictions like bent exhaust, low tire pressure, bad electrical connections/grounds, clogged air filter, etc. are all restrictions that DONT make less fuel go into the engine, they reduce the efficeincy of the fuel thats giong into the engine regardless of those restrictions.... the throttle position controls basically every aspect of the engine's tune... and therefore cannot reduce effieciency by being restrictive.

thats like saying that if you bump the FP up, there will be less restriction on the injectors and pump to put fuel to the cylinders, so you will get better gas mileage.... not exactly i know but thats the best analogy i could come up with in 3 minutes.

mr. b try that and let us know how it works

 

[ninety15.0]

You guys are crazy...the least amount of air that enters the motor results in the least amount of fuel sprayed out the injectors...hense the best efficiency. The most efficient speed and rpm for any given car depend on the gears, powercurve, and aerodynamics of the car. driving around at 75% throttle will most definately not get you better milage....you will simply be using 50% more fuel that you would be at 1/4 throttle.

 

[Dbeck002]

You guys are crazy...the least amount of air that enters the motor results in the least amount of fuel sprayed out the injectors...hense the best efficiency. The most efficient speed and rpm for any given car depend on the gears, powercurve, and aerodynamics of the car. driving around at 75% throttle will most definately not get you better milage....you will simply be using 50% more fuel that you would be at 1/4 throttle.

actually you would be using 200% more fuel at 3/4 throttle as opposed to 1/4 throttle!!

but you are right more throttle means more fuel.

 

[Euphoric306]

actually you would be using 200% more fuel at 3/4 throttle as opposed to 1/4 throttle!!

but you are right more throttle means more fuel.

ahem....