switch to run on 4 cylinders

[lexxxx]

hey guys i had a question i have been thinking about for sum time now. as we all know the new trucks switch to economy mode when on the high way and only use 4 cylinders. i was wondering if anyone had any insight on this question. OK i have a 04 ram 1500 4.7L. and i was thinking about having a switches hooked up to 4 fuel injectors and 4 spark plugs, i wanted to know do you think this would hurt the engine. now besides the obvious stuff of the check engine light being on and having to figure out the right cylinders to do and the o2 sensors. would it actually hurt it just to use for highway travel to save gas or would i use more to keep it at the same speed with 4 cylinders. thanks all.

[hundahunta]

it won't work...when they cut cylinders it usually is done electrically and mechanically...cutting fuel and spark won't help as your cylinders are still pumping air you also need to seal the cylinders or you will get a back pressure exhaust pulse into the intake and so forth...it's more complicated.....it will run rough and the fuel mileage will probably get worse.

[lexxxx]

thats what i thought thanks

[wafrederick]

Plus run the oil that is recomended when doing an oil change or it will not work right.

[thisnametooktolong]

This is what they do to shut down cylinders at the factory

The engineers Just shut off the fuel injectors but.... they have changed the ECM so that it knows that there is extra air coming from the "dead" cylinders or they shut down one bank. As an example the firing order on ford is 142536. Gm goes 123456. In any event they shut down one bank and ignore any data coming from that bank for the O2 sensors. Mostly they do this on 8 bangers but it should work on a 6 banger.
In most engines they do not lift the valve rockers, they just turn off the fuel and let the spark waist. That is the same thing they do in all engines today with coil packs that have two wires going to two cylinders. Cady tried lifting the rockers with tons of problems and abandoned the idea. They no longer do that. The energy lost to pumping air is not that much at partial throttle because they do not get that much air in the first place. The only energy loss is due to heat and flow (almost nothing.) the compressed air stores energy like a spring and bounces the piston back down. Does it save? At idle yes… tooling down the road… not enough to tell. So unless you drive in a traffic jam all the time it is not worth doing. (Been there and don that)

Fooling the ECM so that it thinks that the injectors are firing and adding and switching o2 sensors is very easy if you are an electrocution.... This is the problem. I tried it on a “car-van” by adding a valve to bypass the fuel around one bank. (wwhat can I say I was board) I had to live with the misfire codes because I did not tune the computer to ignore the dead cylinders… fuel savings was almost ZIP. I reset the codes every time I turned that valve on and off
Now I added water and lost the cats on a Sable…….. 37 highway…..29 city the epa says 27/23. Now that is shit hot. It shaved ½ a second on the 0-60 time. 9.5 sucks but it is better than 10 flat