DIY engine kill switch (via Crankshaft Position Sensor interrupt)

[Loren]

Yes, coasting in neutral with the engine off.

Something like this:

Clutch in, shift to neutral, kill, release the clutch and coast. My kill switch is a momentary switch, so as soon as the engine has stalled, I release it, and the ECU sees it as nothing more than an engine stall. (you could get the same effect by turning the ignition key off to kill the engine, then putting the key back into the normal on/run position)

To restart, clutch in, select a gear that will result in low RPM (1500-2000 or so, not critical) for the speed you're coasting. Quickly release the clutch, and put it back in again. You're just giving the engine a quick kick to get it started.* Once it's running, release the clutch normally and begin accelerating (or cruising, or even stopping if you're like me and just want to avoid using the starter to restart).

* You could just as well release the clutch just once, and you can do it that way if you're in a gear that gives you really low RPM. (like maybe 25 mph in 4th) But, doing it that way is a bit rougher. I find it's smoother to give it a quick kick to start it, and then release the clutch smoothly.

[Space Wolf]

Clutch in, shift to neutral, kill,
<snip>
To restart, clutch in,

That sounds like a description of my Auto Start & Go. Except that AS&G is designed to work when the car is stopped. Yet I tried, but unfortunately it doesn't work. Put the car in neutral at 80km/h on an empty road, but the engine didn't shut off. I let the car coast until it stopped, to see where the engine would stop. Well, it never stopped. When the car stood still, I had to press the clutch and release it again to switch off the engine. Pity.

[Eggman]

That sounds like a description of my Auto Start & Go. Except that AS&G is designed to work when the car is stopped. Yet I tried, but unfortunately it doesn't work. Put the car in neutral at 80km/h on an empty road, but the engine didn't shut off. I let the car coast until it stopped, to see where the engine would stop. Well, it never stopped. When the car stood still, I had to press the clutch and release it again to switch off the engine. Pity.

The power brakes need vacuum for boost and the power steering needs the alternator running in case of emergency maneuver. A manufacturer avoids liability problems by not shutting off the engine while the vehicle is still in motion.