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Old 05-08-2009, 11:45 AM   #1 (permalink)
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Kill switch signal cutting options

I've been contemplating doing a kill switch for a while now. I'm just not sure the route I want to take with it. There are several members who have done kill switches and everyone seems to do it a different way! I'd like to take some time to explain the different ways, their pros and cons, and hash out what we think might be the best way.

Cut ignition signal
Cutting the ignition signal is fairly easy. Its a single wire job, but doesn't necessarily ensure that fuel injection stops as soon as you activate the switch. Also won't work for diesels.

Cut fuel injector signal(s)
Cutting the fuel injector signal is a bit more complicated on most vehicles. On throttle body injection this isn't a great option as you still have fuel in the intake manifold and the engine won't die immediately. On batch fire injection, you have two or more wires to cut into and stop signals. On sequential injection you have at least four wires to cut into and stop signals. However, this approach ensures no fuel is used immediately after the switch is activated.

Cut fuel pump power
This is IMO not an ideal way to kill an engine. You have to wait for the engine to die as the pressure is bled out of the fuel system by the injectors. It is, however, a simple one wire option.

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.

So, add your method and/or discuss existing options so we can get an idea of what is best.

Current project: A better alternator delete
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