26 replies to this topic

[Burnard]

Model: Mini Designer
Year: 1988
Any non-standard parts that might be involved with the problem? maniflow exaust with free flow manifold, minispares inlet, AAA needle, Britpart ignition, lucas sports coil.


Description of problem (please be as in depth as possible):
I decided to set my engine up today and fit some of the new parts, i have found that sometimes when i try to turn the engine off, it continues running for about 30 seconds.

I have set the tappets to 12thou, the timing is 10deg advance at 1500rpm (vaccuum disconected).
temp is jsut abouve the blue line on the standerd dial, now sure how reliable that is though.

What could be causeing this and how can i fix it?


Thanks

Chris

[Ouster]

Mixture - it's running too rich.

[Burnard]

It was even richer and it didnt do it then :S

[GreaseMonkey]

Could be a build up of carbon on the head and pistons which stay hot after the ignition is off and ignites.

[ninham]

I second above ^^^

My car does exsacualy the same thing

How do you stop it/fix it?

[il-barba]

do not let it run on for 30 seconds. it will ruin the crank bearings. put it in 4th gear and release the clutch slowly before it begins

[Burnard]

Clean the plugs and head i guess in that case?

[Burnard]

Is there anything else it could be?
It doesnt happen every time, it does seem to be rather random, although the engine has been warm all day rather than running cold with me just driving it in and out of the garrage.


Thanks

Chris

[spiguy]

Model: Mini Designer
Year: 1988
Any non-standard parts that might be involved with the problem? maniflow exaust with free flow manifold, minispares inlet, AAA needle, Britpart ignition, lucas sports coil.


Description of problem (please be as in depth as possible):
I decided to set my engine up today and fit some of the new parts, i have found that sometimes when i try to turn the engine off, it continues running for about 30 seconds.

I have set the tappets to 12thou, the timing is 10deg advance at 1500rpm (vaccuum disconected).
temp is jsut abouve the blue line on the standerd dial, now sure how reliable that is though.

What could be causeing this and how can i fix it?


Thanks

Chris

30 seconds is a hell of a long time to run on for, even if the head was coked up etc.. Does it run on 'smooth' - ie as if the ignition is still on, or is it rough and noisy (as it usually is with hotspot related running on, due to wildly varying times of ignition).

Any chance the coil is getting a live feed all the time (or when it happens at least) , and you have an electric fuel pump so the engine is only stopping once it runs out of available fuel ? (ie the pump is switching off correctly).

Or, is it possible you've connected up the condensor wrongly so its charging and keeping supplying the coil for a while once the ignition is off? (don't even know if that would happen, just a thought)

[Burnard]

Mabe it isnt 30 seconds, i have very bad time counting abilitys certainly feels like it when your trying to work out whats wrong.

Its running on very lumpy, the coil had no live feed, nothing was live, after i turned the ignition off and it kept running, i hit the kill switch.
I have the standerd mechanical fuel pump.
and i dont have a condensor, it it the britpart electronic ignition.

What seems most likly is it either being too rich, only slightly though. or which would be my first thing to check is carbon deposites.

Is there anything i can run through the engine to help clear this, or do i just need to run it for a while to burn it all off?

[96minimig]

Mabe it isnt 30 seconds, i have very bad time counting abilitys certainly feels like it when your trying to work out whats wrong.

Its running on very lumpy, the coil had no live feed, nothing was live, after i turned the ignition off and it kept running, i hit the kill switch.
I have the standerd mechanical fuel pump.
and i dont have a condensor, it it the britpart electronic ignition.

What seems most likly is it either being too rich, only slightly though. or which would be my first thing to check is carbon deposites.

Is there anything i can run through the engine to help clear this, or do i just need to run it for a while to burn it all off?

what your talking about usually happens on very high mileage engine or very rich running engines.. Due to high mileage there is carbon build up and the richness is making is run on as unburnt fuel within combustion chambers is being burnt off.

[Burnard]

55139.6 miles... (im so sad i didnt need to check that)

Ok, so its looking like carbon deposites, and mabe still a little rich.

Is there any way of getting rid of the carbon deposites other than taking the head off?


Thanks

[minimender]

Engine running on is caused usually by RETARDED TIMING or a WEAK mixture.

I'll put my money on timing retarded by a lot, and I'll also wager that someone has set the timing and forgoton to disconnect the vac advance whilst they were doing it. Garages are ofter guilty of doing this especially if they are unused to tuning classic cars. (check your dizzy is advancing propperly as well, could be faulty)

Just my two penneth.

P.S. get the timing set propper and mixture set then go for a blast, that'll burn any exces carbon deposits off for you, don't worry about it.

Forgot to say why it runs on without ignition on.... Exhaust valves get red hot and ignite the mixture..

Edited by minimender, 12 September 2009 - 10:56 PM.

[Sherlock]

My Mini 998 HL has done the same thing since the abolition of leaded fuel, I've polished the chambers cleaned the piston tops, tried colder plugs, which is a good idea with unleaded fuel anyway, tried slightly different timing settings either side of the recommended, nothing makes a scrap of difference, I just stall the engine as I turn off the ignition. The only modification which may work is the air valve fitted to MG Metros to cure this very problem, when you switch off the ignition, a valve opens, allowing air into the inlet manifold, destroying the vacuum within the manifold, hence stopping fuel being drawn from the main jet.

[Burnard]

Engine running on is caused usually by RETARDED TIMING or a WEAK mixture.

I'll put my money on timing retarded by a lot, and I'll also wager that someone has set the timing and forgoton to disconnect the vac advance whilst they were doing it. Garages are ofter guilty of doing this especially if they are unused to tuning classic cars. (check your dizzy is advancing propperly as well, could be faulty)

Just my two penneth.

P.S. get the timing set propper and mixture set then go for a blast, that'll burn any exces carbon deposits off for you, don't worry about it.

Forgot to say why it runs on without ignition on.... Exhaust valves get red hot and ignite the mixture..

Timing is dead on, as per haynes manual (10deg advance@1500rpm with vacuum pipe off) i know because ive only just set it (can i have your money? ), if there is a better setting please recomend.

Weak mixture meaning i need to richen it up a bit?


Thanks


Chris

Edited by Burnard, 12 September 2009 - 11:36 PM.