I have heard that some engines can shut down a cylinder or two to save fuel or limp home without overheating. How is this done? Is it simply making the injector for some cylinders not open so no fuel is used in that cylinder? If that is the case, could someone open the hood, uplug an injector or 2 for a while, when power is not needed, and save some fuel? What made me think of this was the previous post about cylinder deactivation and my 99 V-10 developed a bad injector a couple years ago, one cylinder was getting no gas, it was hardly noticeable when I was not towing, did no damage to the engine, although I did replace it as quick as I could.
Re: Shutting down a cylinder or two for fuel economy
Turing off injectors is how they cool an overheated engine. That cylinder just pumps air in and out without fuel, which cools the engine.
The other cylinders work a bit harder to pump the air. That burns a bit more fuel than if it ran on all it's cylinders.
The engines that disable cylinders to save fuel also disable the valves so that the cylinder is not pumping air in and out. The disabled cylinder compresses and expands the air that's trapped inside it. By not opening the valves when the air is expanded almost all the energy used to compress it is recovered. That won't happen if the valves are not disabled.
Re: Shutting down a cylinder or two for fuel economy
It is a valving issue as well. You get very little advantage if the engine is still sucking in air into a cylinder and then compressing it.
You need to either leave the valve open or close it so there are no forces acting against it.
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1996 F-250 extended cab long box five speed. Home made Tymar, 203 Stat, 60 gal in bed fuel cell, 315/75's, no muffler, ebpv welded open 3" to 3" DP, Babies. 290K, still chugging, and still smoking when cold.
UPDATED 1/1/09 Replace so far. 1 LUK flywheel+clutch, 2 thermostats, 2 set of brakes, 1 set of calipers, 5 CPS, 3 sets of tires, 2 Transfer pumps, 1 Injector modual, 1 Computer, 2 Alt, 2 sets of batteries, 1 Water pump, 6 Belts, 1 PS hose, 2 Sets ball joints, 2 set u-joints, 2 carrier bearing, 2 Speed sensors, 1 oil pres sender, 1 temp sender, 4 sets of e-break cables, 1 front fuel tank, 2 rear fuel tanks, 2 set of glow plugs, 7 Glow plug relays, Oil galley o-rings, Turbo pedistal o-rings, EBPV o-rings, 3 sets of Injector O-rings, 1 Vac-pump, 1 new carpet, 1 total paint job.Total $$$ in repairs v/s miles driven = 4.6 cents per mile. Add fuel to that it jumps to 16.5 cents per mile over the life of the truck.
Re: Shutting down a cylinder or two for fuel economy
Mark and Casey are right, shutting down a cylinder is not as easy as removing fuel. You would have to leave open the intake valve, retime the ignition system for the remaining 8 cylinders and shutdown the fuel. On the V10 it would certainly save some money on highway cruising, but would make for a dog on acceleration and probably cost as much fuel anyway. 1 gallon of gas contains a certain amount of energy, and it takes a certain amount of energy to accelerate your trucks weight. The best thing you can do to save fuel is reduce your acceleration rate, and maintain your desired speed when you get there. Better yet, get a Diesel??!!!
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2001 F350 dually short bed - Dual Alts, Aux idle control, Banks power elbow 4" exhaust, ATS Trans, Gear Vendors OD, Dynotech driveshaft, 2" rear lift blocks, Covermaster cap, Mag-Hytec rear diff cover and trans pan, Bilstien shocks, K&N Filter, Western Diesel chip and gauges, Transfer Flow 70 gal aux tank, alpine fosgate kicker polk 800w 10 speaker system, 2-way alarm w/remote start and turbo cool down function, hella aux lamps.
2000 Excursion - Bilstien shocks, Banks power elbow 4" exhaust, K&N air filter
Re: Shutting down a cylinder or two for fuel economy
First of all, if you unplug an injector your car is going to run like shiit, your check engine light will come on, and you will lose power, if anything it would be a pain in the a** if you want better fuel consumption get a car.
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1993 F-250 5-speed 4x4 7.3L Non-turbo Silver/White Standard cab longbed, American Raching 16.5" wheels, brush guard,Loud duals.
Re: Shutting down a cylinder or two for fuel economy
I believe the vehicles that use the variable cylinder system, are designed to leave the valves closed, with no spark or fuel in the unused cylinder. It would take a valve train redesign and reprograming the computer not to inject fuel and not to spark.
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2008 F250SD Lariat
CC SRW Long bed
V-10 and Torqshift auto
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