Start/Stop Switch for the Engine

[OdieTurbo]

Just started (read "gained enough confidence") killing the engine and coasting up to red traffic lights. The Saturn restarts very quickly, however when I kill the engine, I lose all lights and gauges. Turning the key back to 'Run' brings them back though. Kinda annoying at night.

Anway, it brought me to thinking about a pushbutton start/stop switch on the dash, that way I could leave the car at 'Run' and kill/start the engine as I needed it.

However, I am not an electrical genius. What kind of switch would work best? A momentary switch to replace the 'Start' ciruit would work, but I don't know how it would work to kill the engine.

I may have to research this a bit.

[jwxr7]

I did that on my geo for similar reasons. I just used a momentary switch and put it in series with my fuel injector. It kills it kinda slow (have to hold the switch for a couple seconds till battery light comes on), but it fires up as fast as ever when I bump start. I did like many others and put the switch on the gear shift. Makes EOC and P&G easier . You probably have multiple injectors though, others (with saturns too) have done this mod with more than one injector. I chose to kill the fuel to save fuel, it seems like if you just kill ignition it could still dump some fuel for a moment when killed.

[Gary Palmer]

I put a shutoff switch for the power feeding to the injectors. The ecu typically pulls the injector low, at least on Honda's, which enables the injector. On my Honda, this leaves the lights on, but it does throw a cel light, which doesn't seem to affect anything operating, but is really annoying at night.

[minic6]

I installed my kill switch to the coil, as gas miser stated it does dump fuel. Sometimes after a long coast it has a very long crank as if it lost prime. This is a real problem with a bunch of cars behind you. Look into mech. for the ecm if possible might be easy to locate a kill point there.
Where is acc. on your cylinder lock, rock back or forward. On the Geo you can kill it with the key by rocking one stop back. The buzzer was always irratating when keying back up until with my daughter in the car it the buzzing stops. If you dissconnect the passenger seat wire the buzzers dead.
Keep at it filled up today 57.3 mpg with nothing but a stock metro. I bought new tires and wheels to change final drive hoping for 60mpg.

[diamondlarry]

I'll see if I can dig up the "How to" that I wrote on how I did my injector kill switch on my Saturn. It only requires running 1 wire inside to a switch.

[OdieTurbo]

Originally Posted by diamondlarry

I'll see if I can dig up the "How to" that I wrote on how I did my injector kill switch on my Saturn. It only requires running 1 wire inside to a switch.

Thanks diamondlarry! That'd be great!

In the meantime, I did some thinking:

• Momentary switch for starting the car (it's an Auto, no bump start)
• Momentary switch to kill the engine

This would allow me to leave the key in "Run" keeping all lights on. The switch for the starter will be easy. Hopefully diamondlarry can get me some info on the kill switch. I'll also look into my wiring diagram from my Haynes Manual.

And to the idea of the switch(es) on the shifter... EXCELLENT IDEA!

[diamondlarry]

I couldn't find it here on gassavers but i did find a post I made at cleanmpg.com.

I got a 5-terminal relay and cut all of the power wires going to the injectors. On my car they were all the same color-pink. Then, strip the insulation off the wires coming from the wiring harness and tie them all together.

Then, strip the insulation on the wires that are still connected to the injectors and tie them together.

Next, take the bundle of wires from the injectors and connect them to the terminals on the relay that are normally closed(on).

Next, take the bundle of wires from the harness(hot) and connect it to the input terminal of the relay.

Next, take the wire that supplies juice to the relay and connect it to the hot(harness side) of the power wires.

Next, connect a wire to the ground side of the power relay and run that into the cabin to a switch.

Find a suitable ground and coonect a wire from there to the other side of the switch.

What happens when you flip the switch is, the relay switches the wires going to the injectors to the set of contacts that aren't being used so the injector won't operate. When you flip the switch back, the relay loses power and it switches back to the normally closed set of contacts and the injectors are again ready to operate when the engine is re-started. On my car, I just put the car in gear and quickly let the clutch out just enough to light the ICE then back in untill the rpm's stabilize then continue with the next pulse. Occasionally, I have to turn the key from run to accessory then back to run before the ICE will start. According to the owner's manual it's supposed to do this all the time for safety purposes but the majority of the time it doesn't. The nice thing is that on my Saturn, the accessory posistion is the next position down from run and the power to the radio, electonics, etc. is never interupted and I don't have to worry about accidentally locking the steering column; not good. This also means that there is no distance lost on the odometer while the key is off and you're waiting for the engine to completely stop. I hope this helps. If there are any questions I'd be glad to do my best to answer them.