legacycentral bbs

So, my roommate and a friend show up at my house, are tell me that they need my help with their car. So, I leave watching "wag the dog", to walk outside. Her friend informs me that the car wouldn't shut off. Hmmm, just like my turbo timer . Maybe not. It was some old oldsmobile, with peeling paint. I walk up to it, and try and turn the key. It goes back and forth in the ignition (while the car is running) like a hot knife through butter. No clicks anywhere. I pull the key out, nothing happens.
Hmmm.
So, we decide to bring the car to a local dealer, so that she can have it fixed tommorow. We get there, and decide its a good idea to turn the motor off. So, after not thinking and messing around with a couple things (like seeing what would happen if I pull out a bunch of the spark plug wires to see how many it would take to die, I am guessing all of them, never made it that far though), I just yank the ground on the negative end of the battery. And done.
Here is my question.
How would you kill a car that wont turn off, assuming dissconecting the battery did not work for some reason? What would be the easiest fix? Most of the stuff I could think of would not be good to do with the engine on.
just kind of curious......

put a bucket of water under the intake, and rev the engine.

Steve

Pulling the battery terminal's not good for the car. The alternator's voltage regulator isn't meant to do its job without the battery's helping as a stabilizing force. In fact, the only reason I can think of that disconnecting the battery would kill the engine would be a big voltage spike or drop upsetting the ECU.

You can do something similar to what Laurel said with less risk of hydrolock... if you can block off the intake or exhaust (with a wadded-up wet rag or somesuch) you can force the engine to stop. It's safer to do on the exhaust side since the engine could actually try to ingest whatever you put on the intake side. You hear about potatoes in tailpipes...

Pulling a fuse responsible for ignition, engine management, or the fuel pump would do it too.

'Course, if it's a standard, you can just use the brakes when it's in gear to stall the engine.

I've heard of people spraying Halon fire extinguishers into the intake to stop an engine before too.

Disconnecting a key sensor would do it easily as well. Most GM cars are speed density. You could disconnect the electrical connector from the MAP sensor. Or (if it's a remotely mounted sensor) remove the hose from it, which would make it run so rich it would die. On a Legacy, unplugging the MAF sensor is a very easy way to do it.

Yeah I'd have to go with a sensor like maf/map or something. Maybe plug wires or something but that sounds more dangerous.

take out a spark plug and stick a pipe in the hole

this is a serious problem with diesels.

Oh yeah, it's super scary when a diesel goes runaway... If oil starts leaking into the combustion chamber, even cutting off fuel won't stop the engine. I've heard of diesel-powered construction vehicles rupturing underground gas lines and revving uncontrollably because of the ingested fuel gas.

My vote is

"Pulling a fuse responsible for ignition, engine management, or the fuel pump would do it too. "

that might pull a code on some cars^

taking the coil wire off kills most cars with a external coil.

if u got the intake out u could cover it like some one said

The code would go away after the car started again, since the fault would go away.

The issue with disconnecting coils is that you get your hands near some really high voltages. And if you pull the high-voltage leads the arcing can cause damage to the coil and/or wire terminals.

Plus getting shocked by the coil doesnt feel very good. The fuse idea could even be rigged with a passenger compartment switch!

Hehehe... Most cars come with a switch like that stock, sometimes called the "ignition switch."

Sorry, just playin' with you...

But, yeah, an emergency kill switch is required on racecars, no? I believe those just disconnect the positive leads of the battery and the alternator.