Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: shayla on 11 November 2013, 17:32:14

Title: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: shayla on 11 November 2013, 17:32:14

hi all i have got a vauxhall omega 2.5 TD GLS automatic s reg 1998 i recently at to change the clocks on the car as the speedo and counter rev needles stopped working.fixed that  but i have now got another problem which is beyond me and this is where i need your exsperiance . what the problem is when i turn the ignition key to the off position the engine does not turn off. but if i press the break and then turn the key to the off position the engine will then shut down. i have bought a new ignition switch and fitted it but that as made no diff >:( i have also checked if there are any breaks in any of the wires under the cowling but i can not see any. is there anybody out there that can give me any advice on what my problem is i would be very much appreciated as i am pulling my hair out with this . is there a fuel cut off switch that could be faulty? if so can anybody tell me how to get to it. :D

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: TheBoy on 11 November 2013, 18:08:31

When you say you have to press the brake, you are not having to stall it are you?

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: henryd on 11 November 2013, 19:04:41

Quote from: TheBoy on 11 November 2013, 18:08:31

When you say you have to press the brake, you are not having to stall it are you?

Its auto so probably not ::) :y

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: Agemo on 11 November 2013, 20:18:49

It happened to me once, turned the key off & the engine kept going.  :o I accidentally found that pressing the brake pedal stopped the engine  :). Never happened since  :-X. You could always live with it, not that much of a problem.   :-\

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: Webby the Bear on 11 November 2013, 20:22:04

is this a case of the turbo keeping the engine running when turning off?  :-\ (ps don't berate me if im wrong.... im just learning about turbos at the mo :))

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: henryd on 11 November 2013, 20:27:39

Quote from: Webby the Bear on 11 November 2013, 20:22:04

is this a case of the turbo keeping the engine running when turning off?  :-\ (ps don't berate me if im wrong.... im just learning about turbos at the mo :))

Shouldn't think so Webby,take more than the brake pedal to stop a runaway auto,I reckon it's electrical,earth wire broken or similar.

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: 05omegav6 on 11 November 2013, 20:47:07

Does a diesel stop by closing the throttle? If so could be a stuck/sticky valve, the effect of the brakes being applied upsetting the vacuum enough to stall it... are the diesel and vacuum pump the same unit as per VW tdis :-\

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: Andy B on 11 November 2013, 20:54:16

Quote from: ex taxi al on 11 November 2013, 20:47:07

Does a diesel stop by closing the throttle?  ....

Does a TD actually have a throttle?  :-\  :-\  :-\

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: 05omegav6 on 11 November 2013, 20:57:15

Pass. Never had one, but I know that on some diesels the fuel and vacuum pumps are the same unit... in this case the loss/use of vacuum by application of the brakes was enough to either close the air or fuel off :-\

Title: Re: ignition key will not shut down engine unless break is pressed 2.5 td automatic
Post by: Kevin Wood on 12 November 2013, 12:33:59

A diesel stops by the ignition signal to the ECU being cut. ECU will then shut a fuel valve somewhere - probably in the fuel pump, which stops the fuel supply.

So - there's very little current drain on the ignition supply as there's no ignition system to power - just a signal to the ECU. What I am thinking is that, if something is dragging the voltage on the ignition circuit up, the engine keeps running until the load on the ignition switched supply increases - by activating the brake lights, then it stops.

I think it's possible you have an electrical fault somewhere that's causing this. The problem will be tracking it down!