7 replies to this topic

[eeae6000]

everyonce in a while when i turn my keys off, the motor will run or sputter for a sec or two before turning off, what causes this, as first i thought my mixture was to rich, but its actually a bit lean now cause i have to pull choke a bit to drive and it still does the key thing, what causes this?

[Badboytunes]

Could be the start of carbon build up and this will make an engine " run on"

[eeae6000]

how to i get rid of the carbon build up?

[Elliskwleisk]

It can also occur if the timing is slightly out. I had the same problem and just rotated my dizzy a tiny bit at a time. If it gets worse rotate the dizzy the other way until it gets better. Sorted it for me?

[eeae6000]

ill do that tomorrow, also ordered a timing light, hopefully i can fix it

[Cooperman]

It's quite normal on Minis, especially 1275's with higher compression ratios. It's called 'running on', or 'dieselling'.

Altering the timing will not make a difference unless it is retarded and getting too hot locally in the combustion chambers.

All you do is put the car in 1st gear with the brakes on as you switch off and let the clutch up as the engine revs die. Then it can't run on. Simples.

[Gulfclubby]

If you turn the ignition off, that's that, the ignition is off. The only effect wrong timing can have is that the engine is running too hot. Hot spots in the cylinder head can then ignite the mixture that is being sucked into the cylinder/s after the ignition is turned off. Hot spots can be carbon built ups, casting burrs or glowing sparkplugs if they're the wrong type, for example.

 

Running on can also be caused by a high compression rate and/or low octane fuel. In this case the fuel ignites as it is being compressed in the chamber. That's why running on is sometimes also known as dieseling.

 

Last but not least, it can be caused by a wrong mixture, or if the choke is stuck open/doesn't close fully.

 

I'd start with the easy solutions first: take the plugs out, have a look if they're dirty and clean them with a copper brush. check the choke is operating correctly and make sure there's oil in the dashpot too.

[iwatkins]

Doing lots of short runs? That doesn't help.

If its too lean, then I would sort that first. Running on the choke all the time isn't going to help.