14 replies to this topic

[998 mini]

i have a problem with my mini. when i switch the ignition off after the car has been runnin it keeps runnin on, sometimes it can go on for at least 5-6 seconds or 1-2 seconds.

i just dont no why it does it and can i stop it?

does a 1989 mini have a anti-run-on valve?

[Wil_h]

No, your mini won't have an anti run on valve. These high compression engines seem to have a habbit of running on. I tried everything on mine to stop it but all to no avail.

Fitting an anti run on valve will cure the problem though.

Sometimes carbon build up can cause run on, so this might be worth investigating first.

[Big_Adam]

I had cronic run on till I twiddled the timing. Still get a bit though.

You can stop it via the clutch. Put the car in gear. Turn off the engine and slowly raise the clutch to stop the engine.

[Aus]

Heres a wierd one ! Supposedly if you have an old head that had had plently of spark plug changes the threads get worn and reduce the thermal transfer into the head, hence the plug runs hotter. You could try going down a notch to a cooler plug, might help.

Same thing happens when people fit exchange flowed heads. Occasionally you get onetaht has been "made" on an old casting that was put in as an exchange head that has worn plug threads and causes run on - people have just put it down to having a "tuned" engine.

As said above, check the timing and mixture to illiminate these as possible causes. Might be worth whippng the head off and giving it a de-coke to as extreme build up of carbon deposits can cause run-on too

[minimender]

Modern day fuels do not help as the timing is retarded to compensate and this leads to exhaust valves getting very hot to the point where they are glowing.
Fuel mixtures are set to lean these days in an effort to cut emmissions but older engines don't like it and tend to run hot hence pre ignition (run on ) after switching off.
Ignition timing should be advanced as far as poss to the point of pinking then backed off a bit on an old engine.
The settings in the manual should be disregarded to a point and the engine given what it needs rather than what it should have by the book.
Wear in the distributer and timing chain wear both contribute to retarded timing which then leads to pre ignition (run on).
In summary I would suggest running the mixture slightly rich rather than lean and timing advanced as far as poss without pinking.

[T.Harper]

You can stop it running on by pressing the accelerator pedal as you turn the key off. I know it sounds backward, but it works! I have one of these HC engines and I do this all the time. Don't worry, it doesn't flood it either!

[998 mini]

ok cheers so where can i get a Anti-run-on valve from and how do you fit them?

[minimender]

You can stop it running on by pressing the accelerator pedal as you turn the key off. I know it sounds backward, but it works! I have one of these HC engines and I do this all the time. Don't worry, it doesn't flood it either!

That's a good idea, the extra unburned fuel will cool the valves and combustion chamber.

I always pull the choke at the same time as I turn off at night if the weather is cold, just enough to put extra fuel in inlet, then it fires first time in the morning.

[Pauly]

The engine might need de-cokeing, the hot carbon ontop of the pistons would still be igniting the petrol after you have turned off the ignition. Could also be a timing issue.

Paul.

[swiftminiphoenix]

adjustment of mixture and idle on carb should help - sorted mine

[MiniAuto]

mine had this issue if was running rich and this bult carbon up on the head this carbon remains hot and can light any unburnt petrol which there is always a little bit of well if you have the manual fuel pump anywho .. a good decoke and a quick service (timing)and tune.. now sorted

[T.Harper]

You can stop it running on by pressing the accelerator pedal as you turn the key off. I know it sounds backward, but it works! I have one of these HC engines and I do this all the time. Don't worry, it doesn't flood it either!

That's a good idea, the extra unburned fuel will cool the valves and combustion chamber.

I always pull the choke at the same time as I turn off at night if the weather is cold, just enough to put extra fuel in inlet, then it fires first time in the morning.

it just works. My car is fuelled and timed correctly and still occasionally runs on, so I just do this, and have done it for years now, it's turned to habit!

[andersemil]

I have the same problem where my mini just keeps chucking on after ignition switch-off since I retarded my timing a bit (was pinking slightly).

I came across this document while trying to fix it:
http://www.mgtoronto...tion-run-on.pdf

Wonder if the same trick would apply to a Mini... I'm gonna have a go at it, see if it does anything for me, if not I'll just rip it out and think about advancing the timing again or enriching the mixture slightly.

EDIT: Never mind, I found out this fix is for a different issue... I guess my problem is I retarded the timing too much and will have to readvance it to a slight pinking... sigh.

Edited by andersemil, 07 August 2008 - 08:53 AM.

[1987_ParkLane]

Sometimes carbon build up can cause run on, so this might be worth investigating first.

Yes I'm sure this is one of the main problems

You can stop it via the clutch. Put the car in gear. Turn off the engine and slowly raise the clutch to stop the engine.

This is what I do with mine, I kind of stalls it.

[Strontium Dog]

You can stop it running on by pressing the accelerator pedal as you turn the key off. I know it sounds backward, but it works! I have one of these HC engines and I do this all the time. Don't worry, it doesn't flood it either!

That's a good idea, the extra unburned fuel will cool the valves and combustion chamber.

I always pull the choke at the same time as I turn off at night if the weather is cold, just enough to put extra fuel in inlet, then it fires first time in the morning.

it just works. My car is fuelled and timed correctly and still occasionally runs on, so I just do this, and have done it for years now, it's turned to habit!

This is a very bad idea as you are pouring fuel into your cylinders and washing the oil off of them. Consequently when you next go to start the engine you get increased bore wear due to inadequate lubrication of the cylinders. Bore wash is a major contributor to premature engine wear!

Sorting the problem is down to correct engine and ignition set up. I.e. do a decoke and then set up the points with a dwell meter and only then look at timing. This is assuming that you have already adjusted tappet clearance etc. and that your engine is not fubar'd and isn't drinking oil and carbonising up all the time