Kill switch signal cutting options

[doviatt]

With out the cut off circuit we turn the key from ON to ACC, and then back to ON when engine has completely stopped. Then it is in the ON position waiting for a bump start or key start. This is a completely normal situation for any car.

Does interrupting the ignition wire at the key switch accomplish this seeming normal way of doing this?

Doesn't this ignition wire at key switch control the fuel and spark at the same time?

I've heard concerns of fuel with no spark and spark with no fuel as potentially problematic with the spark ignition only, or the fuel injector kill only options. Are these concerns even valid? I guess in either case you get a few extra sparks or some fuel pumping, but only till the engine is dead...then all things are truly stopped? Sensors and computer codes seem to be the only potential victims here.

Maybe my naivete keeps me from understanding that your solutions are probably providing the same solution. Since mine is old enough not to know what a computer code is I probably have less to worry about?

[dcb]

keying off also messes up the gauges in the saturn, the speedo takes several seconds to "come back online". The metro starts beeping at you. The mpguino also stops tracking speed/distance while the key is off and I'm sure a scangauge wouldn't be real happy either.

[doviatt]

Got it. Thanks for the clarification. The dilemma makes sense now also.

[Bearleener]

I second MetroMPG's and dcb's approach, interrupting the signal on the wire coming from the Hall sensor on the distributor. In my car it's a yellow-and-green wire. Been using it for about 2 years without any problems. (At first I was afraid I might be damaging the catalytic converter, but the car just passed the emissions inspection with flying colors.) Should work on any engine, it will cut both fuel and spark. I bumpstart whenever possible but I also installed a start button, tapping a relay into the wire going from the key's starter switch.

Other options: My car doesn't have an injector fuse. Cutting the fuel pump would give a delayed response and I suspect the ECU may try to compensate for waning fuel before it dies.

[doviatt]

Originally Posted by MetroMPG

My switch is inline with the coil pickup in the distributor. Is this what you're referring to as "camshaft sensor", dcb?

The engine occasionally stumbles when it's used. That could be dieseling from fuel still coming through the throttle body - I don't know. I've never tried any other method.

My repeated advice - regardless of method chosen - use a momentary switch, not an on/off one. (Safety implications. You would think after hundreds of uses that you'd always remember to turn it back on, wouldn't you? )

I installed mine last weekend.
I followed this advice and it worked perfectly! Thanks!
I went with the black/white wire off the distributor on the Metro. According to the schematic they both should work as stated but black/white seemed a better choice.
I did use a small normally closed momentary which I mounted like a trigger on my shift knob. I was a bit concerned about the long term reliability of this momentary switch so I also added a bypass or override toggle switch in parallel before the momentary. This way if the momentary ever fails open (no start) I can flip the toggle it closes the circuit and things are running again.

Looking forward to effortless EOC. Now my blinkers still work in EOC, no beeps, and once I get my MPGuino finished it will also stay on.

[Daox]

Just an FYI, the guino will always stay on since it is wired to 12v constant. The problem is that when you key off, the sensors don't have any power going to them so the guino reads no signals from them. Glad it worked out for you! My turn next I guess.

[Piwoslaw]

For anyone who finds this thread, I'll add that there is a thread dedicated to Killing a diesel.

Originally Posted by Daox

Cut the crankshaft position signal
I think dcb recently posted about using this method. I'm not sure if it cuts fuel and ignition all at once? If so, this would be great one wire solution.

In my case (HDi commonrail turbodiesel) I can unplug the crankshaft sensor with no change in engine functioning. Unplugging the camshaft sensor doesn't stop the engine, only keeps it from starting if already stopped. No codes. Haven't tried pulling both sensors at the same time.

[deepsky]

I know this is an old thread but thought this would be as good a place as any to ask. I bought a 94 metro xfi last month. Would it be better to use the red wire which is the ignition reference high or the white wire which is ignition reference low, or does it matter? My service manual says that at the ecm the red wire = light green pin b1 and the white wire = purple pin b9. Has anyone had problems using the wires under the dash as opposed to near the distributor? I only ask because for some reason many seem to have problems tapping into the fuel injector wire near the ecm when installing their mpguino ( which I received about 2 weeks ago but have yet to find the time to install.)

[JacobAziza]

Originally Posted by dcb

keying off also messes up the gauges in the saturn, the speedo takes several seconds to "come back online". The metro starts beeping at you. The mpguino also stops tracking speed/distance while the key is off and I'm sure a scangauge wouldn't be real happy either.

This is why I love owning pre-computer cars.
I did exactly what doviatt suggested, and it works great. Simple, reliable, effective.

On to the present:
On a car with DFCO, would there be a way to tap into that system, and activate in manually? Since it is built in, seems that might be the way to stop fuel to the engine which the computer and sensors and everything would object to the least

[watercat]

I have been following this forum for some time. I have two 1994 metro's one auto and one manual. I have in my manual metro a brand new motor with 1 mm oversized pistons the compression raised to 11 to 1 ratio. stainless valves bronze guides 3 way cut on the valves and the motor was balanced. all marks on everything is to factory specs. I also did the grinding on the head i think it was call sign grooves? so i know have 1000 miles on it and it gets exactly the same gas mileage as when it had 176k on it. about 43 mpg

i'm documneting every thing in a note book as i drive to keep some records.

So now it begins trying to find the tweaks. my first tweaks i thought would be a kill switch and manual throttle handle.

My idea on the kill switch is to kill the cam sensor or distributor and use the clutch saftey start switch to do it. You dont need to cram the clutch pedal to the floor to shift so i thought why not disconnect the switch and have it interupt the cam sensor since you need to clutch the engine and kill the switch at the same time to be the most effective.

has it been tried yet?