Delayed Ignition Cutoff

[kupcar]

Im having some issues with my delayed ignition cutoff. Once the ignition is turned off, the car will continue to run for up to a couple of minutes. Strange thing is, if I press the brake pedal down, the car will shut off. Anyone have any ideas on why this is happening? Thanks.

[DRACO A5OG]

Ignition switch may be going or connector/s loose for the kill component, which car is this happening to? 76 or 86.

[T77911S]

perhaps a vacuum issue with the engine. the engine is kind of struggling to run so maybe the change in vacuum kills it.
you might pull a vacuum on the hose to the booster to check for an air leak.

if the brake pedal is actually causing it to shut off then try this.
put your foot on the brake before turning the ign off, then turn it off. if it runs on like it should, you either have an air leak or you have nothing to worry about.

I will try it on my 930

[Topocalm]

Originally Posted by kupcar

Im having some issues with my delayed ignition cutoff. Once the ignition is turned off, the car will continue to run for up to a couple of minutes. Strange thing is, if I press the brake pedal down, the car will shut off. Anyone have any ideas on why this is happening? Thanks.

I have the exact same behavior on my 77 930! Will follow this with interest...thanks for asking

[proporsche]

Hi Topo in Germany..have you replaced in your engine compartment the yellow relay.It is exactly for this on your 930

Ivan
this one

here is some reading
1989 930 - Won't Start - No Fuel

[kupcar]

Everyone, thanks for the input. The car is a 76 930. It doesn’t have the yellow relay that the later cars have. When the engine runs after the key is turned off, it will run normal, no laboring or sputtering. It just takes awhile to shutdown. Pressing the brake pedal will immediately kill the motor once the key is in the off position. It’s very strange. I thought maybe the ignition delay relay is sticking. Don’t know why pressing the brake shuts down the car.

[proporsche]

just an idea did anybody installed on your 930 3rd brake light?

Ivan

[Topocalm]

Originally Posted by proporsche

Hi Topo in Germany..have you replaced in your engine compartment the yellow relay.It is exactly for this on your 930

Ivan
this one

here is some reading
1989 930 - Won't Start - No Fuel

Hi Ivan,

I did change the relay - no change to the situation. Almost exact same behavior Kupcar describes - maybe a little sputtering when left running and shutting off itself. When brake pedal is pressed it feels like turning off the ignition.

Matthias

[smokintr6]

I have a 79 SC that continues to run, but only if the headlights are turned on, AND the brake pedal is pressed. Releasing either the brakes or turning off the headlights turns off the car.

[rbogh901]

Engine run on. Could be alternator backfeed. Need a diode. I think John W had one w a similar brake light association. Comes up a couple times a year.

[proporsche]

ok TOPO i will search in my brain....to be continued;-) if i remember correctly this relay should have a little piggy tail brown wire....do you have that on yours? Again i guess it was on later models...
Ivan

[pampadori]

never driven a 930 so i'm not experienced on this but are you guys saying that you've installed a turbo timer and touching the brake causes it to shut off? Or did the 930 come from the factory with a turbo timer?

seems like a nice feature actually to prevent theft when its in run down mode.

[kupcar]

I don’t see a third brake light wire. It’s a US car, so no rear fog as well. Once the key is turned to the off position, the “G” alternator light will illuminate on the gauge. I’ve lived with it forever, just wondering why it does what it does. I though maybe the delayed ignition relay was finicky or sticky. Still doesn’t explain when it will shut off with the brake depressed. Thanks everyone for your thoughts and ideas.

[proporsche]

As has someone mentioned the alternator ...check what is the out put..thinking if you apply brakes it will take some voltage away from the system and stops feeding the fuel pump.As another guy(above) said he has to put the lights on...Check the voltage before you step on brakes and what it does??
Ivan

[75 911s]

If you have the wrong brake light bulb in, it can cause this weird behavior. Did you recently change any of your bulbs? If you failed to put a dual filament bulb in one of the tail lights, the car will stay running until you depress the brake pedal.

[proporsche]

Duane..he said "I’ve lived with it forever, just wondering why it does what it does."

your idea sounds interesting but i doubt it..to be continued...;-)
Ivan

[kupcar]

I haven’t been able to check my alternator readings yet. The light bulb thing seems interesting. I haven’t changed the bulbs recently, but I’ll take a look and make sure the bulbs are correct. Yes, this has been the way the car has been since my ownership many year back. I just have never investigated why it did this. I guess I’m running out of things to do and thought that someone has experienced this issue or knew what the fix is.

[T77911S]

for those that don't know,

the 930 is SUPPOSE to run on after you turn the key off.

to the OP
my 86 does not stop when I press the brake pedal.

I would really look into an air leak in the booster system. either the hose or the booster itself. probably the booster
pull a vacuum on it and see if it holds. do it at the hose in the engine bay.


try the other test I suggested.
put your foot on the brake THEN turn it off

[emac]

I know there are no stupid questions or answers for that matter —so could the run on be to cool the turbo a bit

[T77911S]

i think it has more to do with fuel.
don't know if it is a vapor lock prevention or what.

people think I am crazy when I tell this.
I was working on my 930 one day. it cut off. I jumpered a ground wire to my CD. there was a spark and the engine fired up. NO starter. (I was doing some testing on the ignition sys).
so I figure it is to relieve fuel pressure.

it takes longer than that to cool the turbo.