Engine keeps running with key out.

[Tristian87]

Hi any help will be appreciated, 

     I got in my 2009 TDI VRS This morning to got to work, I drive to work fine but when I got there turned off the ignition and took the key out but my engine kept running. Radio and instrument back lights turned off but a few warning lights stayed on hand brake, esp and power steering. I stoped the engine by stalling but the warning light remained also with the sound of an energised solenoid or pump maybe. I tried to start the car again but it just kept turning over, so I disconnected and reconnected the battery now the car started but again wouldn't turn off. I'm thinking ignition has anybody got any ideas? Thank you. 

[Stuart-h]

Could be the solenoid. Had the car on a diagnostic computer at all?

[skodacarman]

There's no separate electrical ignition system on a diesel, that's why they keep running even after the so-called 'ignition' is turned off.  They are stopped by the solenoid that cuts off the fuel supply.  Like Stuart-h says, check that first.

[cheshire_cat]

can only think the contacts in the switch have "arced" over with wear and carbon -ised  grease    need to come off to check  

[SuperbTWM]

4 hours ago, skodacarman said:

There's no separate electrical ignition system on a diesel, that's why they keep running even after the so-called 'ignition' is turned off.  They are stopped by the solenoid that cuts off the fuel supply.  Like Stuart-h says, check that first.

 

I think your mistaking a modern diesel with one of 30+ years ago.

 

Edited 17 November, 2017 by SuperbTWM

[skodacarman]

17 minutes ago, SuperbTWM said:

 

I think your mistaking a modern diesel with one of 30+ years ago.

 

 

Not at all.

 

In a petrol engine, the fuel/air mixture is ignited by an electrical spark. You stop them by stopping the spark.

 

In a diesel engine, the fuel/air mixture is ignited by the heat of compression. You stop them either by cutting off the fuel (starving them), or cutting off the air (choking them).

 

Either motor can, of course, be stopped by stalling.

 

A diesel's glow plugs are just used to pre-heat the cylinders and make starting easier usually at  a chilly 5C or lower.  They have no role once the engine is running.

[Breezy_Pete]

Might be an idea to check your oil level. 

[SuperbTWM]

6 minutes ago, skodacarman said:

 

Not at all.

 

In a petrol engine, the fuel/air mixture is ignited by an electrical spark. You stop them by stopping the spark.

 

In a diesel engine, the fuel/air mixture is ignited by the heat of compression. You stop them either by cutting off the fuel (starving them), or cutting off the air (choking them).

 

Either motor can, of course, be stopped by stalling.

 

A diesel's glow plugs are just used to pre-heat the cylinders and make starting easier usually at  a chilly 5C or lower.  They have no role once the engine is running.

 

A modern diesel can't run on its own just on compression and fuel like they used to ( unless you get a runaway from the likes of a bad turbo seal)

 

The injectors are electrically controlled, the timing is electrically controlled, the fuel is electrically pumped etc. etc. 

 

There is no magical solenoid that cuts the engine out. 

Edited 17 November, 2017 by SuperbTWM

[skodacarman]

10 minutes ago, SuperbTWM said:

 

A modern diesel can't run on its own just on compression and fuel like they used to ( unless you get a runaway from the likes of a bad turbo seal)

 

The injectors are electrically controlled, the timing is electrically controlled, the fuel is electrically pumped etc. etc. 

 

There is no magical solenoid that cuts the engine out. 

 

Valid and helpful points, Superb TWM.  You're right and I'm wrong - there is no fuel cut off solenoid on the Octavia. Damn! That didn't help, then.

 

Runaway is rare, but it just shows any diesel motors can run on their own just on compression and fuel alone (often sump oil) without any help at all from any of the electric systems. 

 

My point is that the injectors or the fuel pump are not an ignition system - they don't cause the fuel/air mix to ignite.  There is no ignition 'system' in a diesel. 

 

So OPs musing that it could be the ignition system isn't going to help him - he won't be able to find one on his motor. But your post will help him to consider the injectors, pump etc.  Note that PD tandem fuel pumps are driven off the camshaft, not electrically.

 

I forgot, magical solenoids are only fitted to Hogwarts diesels, and you're right, they're at least 30 years old.  

 

 

[pikpilot]

Compression ignition diesel engines will run on if there is another source of fuel after the main fuel source has been shut off.

One cause is that the engine oil is being used as the fuel because of failed bearings in the turbo. As said above, check your oil level.

I had a car in the 1990s where the driver's handbook mentioned the possibility of run on and told you to put the car in gear with the brakes on and to stall the engine.

Edited 17 November, 2017 by pikpilot
Oh, and it had a solenoid valve plus a manual cut off in case the solenoid stuck

[SuperbTWM]

1 hour ago, skodacarman said:

So OPs musing that it could be the ignition system isn't going to help him - he won't be able to find one on his motor. But your post will help him to consider the injectors, pump etc.  Note that PD tandem fuel pumps are driven off the camshaft, not electrically.

 

 

 

 

 

He wasn't talking about an ignition system, he means a problem with the ignition switch.

 

Now of course I could be wrong here, but it sounds to me from the original post that the engine continued to idle as normal. An engine running on engine oil or engine oil contaminated with diesel, would not produce a smooth idle.

 

Also take into consideration that when the engines is turned off the anti shudder valve closes which effectively closes the intake up which would also make it very hard for the engine to idle.

 

And yes, tandem pumps are driven from the camshaft, but couldn't a 2009 car be a CR?

 

 

[Tristian87]

Thanks for all the advice. I have checked the oil and that was ok. 

 

I've took the ignition switch to bits and back together again. Problem solve. I think dodgy connection in the ignition so I have a new one ordered. Easy enough job to do. 

 

Again in thanks for the tips. 

[SuperbTWM]

2 hours ago, Tristian87 said:

Thanks for all the advice. I have checked the oil and that was ok. 

 

I've took the ignition switch to bits and back together again. Problem solve. I think dodgy connection in the ignition so I have a new one ordered. Easy enough job to do. 

 

Again in thanks for the tips. 

Glad to hear you got it sorted mate