engines over run

[Matt~Attude]

when i turn the engine off it sounds like its trying to start itself. is this ignition timing
-matt-

[Stephen]

tis called running on.... can often be happen when u use cheap and low octane fuel like tesco petrol. Tends to happen more when u hav a higher compression ratio apparently. Im sure someone else can go in to a bit more depth on that one......

[MiniHaven]

hi matt could also happen if you have been running a bit rich for a while and the piston chamber gets sooted up , deposits of carbon form on the non swept parts of the bore and when engine is turned off these deposits are hot enough to continue burning petrol as the older engines have no ability to "switch off the fuel" as it is carried by the simple induction of air when it is turning over , phrased as over run .
cheak your mixture and shove some redex down her throat to decoke .

[Matt~Attude]

ok shawn i will do she was running rich for a while so im guessing thats wat it is cheers

-matt-

[Miniböttcher]

try getting your emissions checked. some one will be able to check it and set it right. have you up dates to a bigger exhaust or a k&n still filter. if so you will need to get a new needle. before doing the above

do a engine flush. they sell it at car shops very easy to do gives your engine a good clean out and my sovle the problem

or take it for a long drive to give your engine a clean out that always worked on my mini.

dean

[Stephen]

I wouldnt use engine flush on a mini cos a series are already renowned for leaking oil badly and the flush could remove deposits that are helping to keep it sealed up. Have u tried it on a mini? just going by the training from work

Stephen

[MiniGT5]

you could fit an anti run on valve to your inlet manifold as per late spec U/L engines with servos that destroys the induction vacume when the engine is turned off and should solve your probs.

N

[fazman]

One other thing to check is the idle speed if it is too fast this can cause it as well.
FAZ

[monkeyjim]

blimey ,

matt you have most likely answered your own question in the first place .
Pre ignition , the mixture is igniting b4 the spark
You have a standard 998 bar the exhaust .

Check timing,mixture and fuel grade .

Dave

[Matt~Attude]

well iv checked the mixture sorted that out, its spot on now, set the idle speed to 500 rpm. its made a diffrence not doing it so much, just the occational rumble after ignitions turned off. im goin to check the timeing and think about getting an anti run on valve.
cheers
-matt-

[monkeyjim]

Been driving 998's for 18 years now . You will not need the valve a well sorted standard system is all that is required .Sort the timing first , messing with the timing affects the idle speed , the idle speed affects the mixture. Pay Shawn to do it , he can get it done accurately . Then if still a problem look at other things within the engine bay , maybe it needs a decoke .
You have changed the exhaust As Dean has mentioned a change of exhaust can affect things and a differant carb needle may be required. Really only satifactory way to sort the required needle out is to rolling road it.
Dave

[vanman262s]

if it is runing a bit hot will cause this as well