engine doesn't want to stop!

Post by **mogatron** » Fri May 09, 2008 11:19 pm

hi all, having a bit of trouble when turning mogatron's engine off. i turn key and ignition goes off but her engine keeps turning over untill you press the accellorator pedal. gives a funny burning smell too.
anybody any ideas whats could be wrong?

Post by **Kevin** » Sat May 10, 2008 12:30 am

Has it been doing it for a while and has it been getting worse, it could be the timing is way off or carbon on the valves.

Post by **kennatt** » Sat May 10, 2008 7:53 am

its called dieseling,check the timing is spot on,retarding the ignition slightly may help,caused by the build up of carbon on the head/top of the piston.A hot spot forms and ignition is continued via the hot spot.If you can find an old mini or mgb (Probably not) they had an air bleed valve which opened when you turned the ignition off and let air into the system to stop the engine.Not sure but think other makes had a similar system. The cure Would be to decoke,or try red x treatment to clear the build up of carbon.Or simply put it in gear and let the clutch out with the brake on. Once had the same trouble on an mbg and never really cured the problem Good luck with it

Post by **Peetee** » Sat May 10, 2008 7:59 am

Find somewhere remote before you try the redex. What comes out of the exhaust can be a bit antisocial. After I put it in for the full decoke option (stationary, warmed engine) it was like driving the Flying Scotsman down the road!

Post by **mogatron** » Sat May 10, 2008 5:42 pm

its only just started this week. just tried changing the points and timing and no better so i guess redx is the way to go. thanks guys

Post by **Packedup** » Sat May 10, 2008 7:33 pm

kennatt wrote:its called dieseling,check the timing is spot on,retarding the ignition slightly may help,caused by the build up of carbon on the head/top of the piston.A hot spot forms and ignition is continued via the hot spot.If you can find an old mini or mgb (Probably not) they had an air bleed valve which opened when you turned the ignition off and let air into the system to stop the engine.Not sure but think other makes had a similar system. The cure Would be to decoke,or try red x treatment to clear the build up of carbon.Or simply put it in gear and let the clutch out with the brake on. Once had the same trouble on an mbg and never really cured the problem Good luck with it

Unleaded A series Metros have the valve too - Mine's disconnected as it was failing and sounding like a canary stuck in the engine bay on over run!

It's hooked up to the brake servo pipework out the inlet manifold, I'm not sure how easy it would be to plumb one in efficiently unless there's something to stick it on on the manifold.

Post by **chickenjohn** » Sat May 10, 2008 8:49 pm

Another cause of engine running on as well as the excellent suggestions above- try turning the idle speed down. Too fast idel can cause these problems.

Post by **youngun** » Sat May 10, 2008 9:15 pm

Sounds like the hot carbon making it run on......my Toyota field car was terrible for it. I could actually drive around with the ignition off!

Post by **bmcecosse** » Thu May 15, 2008 11:55 pm

Tends to be caused by retarded ignition - may be better if you advance slightly but don't let the engine 'pink'. Also - sometimes a change of petrol make helps, and maybe time for new spark plugs. And of course it maybe just needs a good hard fast run if it's been doing short runs. The Mini lads claim it can be cured by running some water through the engine - they suck it up the little vacuum pipe with hot engine at fast idle and this is said to be less 'offensive' than the Redex trick. Final cure if all else fails is head off and good de-coke.

Post by **simmitc** » Sat May 17, 2008 9:15 am

Not deliberately taking opposite sides, but I've found it caused by ignition too far advanced, so retard it a little. Another cause we had once was a small (pin) hole in the manifold. Really obscure, but as soon as we changed the manifold, the problem went away; adn came back on another car when we tried the old manifold on that. Quite conclusive!

Post by **bmcecosse** » Sat May 17, 2008 10:46 am

Generally retarded ignition leads to hot running - which causes something to glow in the head and therefore keeps the engine running after the spark plugs have been switched off. Interesting about that manifold - because again rich running will cause carbon deposits which can be the 'glowing' thing, and a manifold with a little hole would normally cause weak running with no carbon - unless the mixture of course has been over compensated for the leak at idle - causing over rich running under power.

Post by **kennatt** » Sun May 18, 2008 8:48 am

on the mg it was definitely less of a problem when I retarded the timing

but I do agree that a retarded engine runs hotter.