Creating a Switch to Shut Off Cylinders on the Fly

[Flatland2D]

Remember there are several thousands of volts across the spark plug wire. If you used a switch to directly cut off current to the plug, the high voltage would surely jump the contacts of the switch and short it out.

[SVOboy]

Surely there is someplace to control power to the plugs besides the actual wires? I would think so, but snuggling into the ecu might not be the best idea for something meant to be simple, or mehbe this is actually a hard thing to do. I figure someone just needs to do it and leave the plugs firing to see if it helps mpgs before we get all complicated with it.

[Flatland2D]

That's a good point. There's no reason to get complicated if the principle just won't work. I really don't see why you would need to worry about the sprak plug still firing. Even if they did wear out slightly faster, they are only $1.50.

I'm not an expert on ignition systems, but I would think most of the control is being done by the distributor. I know the ECU can affect timing but I'm not sure how. Maybe the ECU can only shift the timing but not cut it off completely? The entire system might be high voltage.

Come to think of it, you could effectively turn off the spark plugs by shorting them out. You'd put a switch in parallel with the plug and when it's closed, there would be no gap. You'd also need a resistive load in series with the switch, but this would probably be the simplest way of doing it.

[kickflipjr]

Any person who mods turbochargers will tell you that if you go too lean it will destroy the engine.

I assume it would be ok if the spark plugs were shut off along with the fuel injectors. But i'm not doing that, don't turst my wiring ability with spark plug wires.

[SVOboy]

That's true about being to lean, of course, but I don't think this would really lean it out, you'd still be taking in 14.7:1, just only blowing it up in two cylinders instead of four.

[GasSavers_Diemaster]

we could devise a method where, at highway speed, the injectors (mpfi) shut off for 1 & ,3 a pice of cardbord gets wedged between the contacts in the dizzy to keep the plug from firing, and a metal plumimg valve would open or vent between the spark plug and the head.
this would elimate all drag from the 2 unused cylenders. we could get advanced and evrey other fring order the 2 would switch. so 1-3-4-2 would die then next 1-3-4-2 would die. :P

in thearoy this is posible all within the ecu, except the vent valves but it could work

my car has I-VTEC & I-CCSY (cylender canceling system) :P

[SVOboy]

Wow, when you say in theory that this would work, I understand a bit from the ecu point of view, but not the mechanical point. So I'm wondering would you be able to chip for that and then not vent and see an improvement or would you have to do the whole damn thing?

On a related note, is chipping the pm5 possible? I want to lean out idle and some cruising speeds. ^_^

[GasSavers_Diemaster]

yes it is possable but your onn your own whin it comes to reprograming it. i spent 2.5 years looking and i couldent find ****.

[SVOboy]

Yes, I looked on pgmfi and the thing was just like: dpfi, the bastard that is like no others. I figure I should at least be able to find a base map to work from right?

[Flatland2D]

Remember that when the engine is being overdriven (coasting but still in gear) the ECU detects this condition and usually cuts off the injectors itself. There is obviously no short term effects of turning off injectors and leaving the plugs firing. I doubt there would be any significant long term damage also.