18 replies to this topic

[Andy 5]

Hi, i have a 1989 mini mayfair with a recently rebuilt engine. The problem that i am having is it is misfiring on cylinders 1 and 3 at all engine speeds and loads. I have done a compression test and checked that all of the spark plugs are working. When the engine is running i have disconected the ht leads to 1 and 3 and it make no difference to the way it runs, but if you disconect the ht lead running to 2 or 4 the engine cuts out immediately. I have tryed swapping the ht leads and spark plugs around and it makes no difference to how it runs. I have checked the firing order and that is all correct, also, the spark plug in cylinder 3 is very wet after only a few seconds running but the other three are dry when removed.

Engine spec as follows:
998cc engine bored out to 1024 with +40 pistons
Reground and ballenced crank
Refurbished standard cylinder head
Metro inlet manifold
Recently refurbished HIF 38 carb
Standard distributor with electronic ignition
Cone air filter
Large bore fletcher exhaust

Compresion readings as follows:
Cylinder 1 - 160psi
Cylinder 2 - 160psi
Cylinder 3 - 180psi
Cylinder 4 - 170psi

Any help and advice would be greatly appreciated, thanks

[sledgehammer]

I would look at the dizzi cap for a crack in the area of 1&3 - or corroded terminals ? look in the dark for sparks in the HT system (engine running)

 

That is the only thing in common with 1 & 3 cylinders - that they are next to each other in the firing order

 

another remote possibility is the dizzi is very worn & is missing the trigger signal on 1 & 3 , 

 

does it have a bright spark on 1 & 3 ?

 

if there is excessive fuel in 1 & 3 that may stop combustion for a short while

Edited by sledgehammer, 30 July 2015 - 08:12 PM.

[Andy 5]

The distributor cap is new and all of the terminals are clean, and it misfire from start up even if it has been sat standing for a while, i have replaced all of the ht leads and spark plugs and it is still the same. I have also put a new mini sport gold coil on to make sure that there is a strong spark. Is there any way of checking if the distributor is missing the trigger sensor on 1 and 3 as the distributor is original to the car?

I have also used the inline connectors that you can put in between the ht leads and the spark plugs and they all light up fine on all four cylinders showing that there is power going to all four spark plugs

Edited by Andy 5, 30 July 2015 - 08:37 PM.

[CityEPete]

Could the dizzy be 180 degrees out?

[Andy 5]

If i swap the leads around on 1 and 3, will that effectively turn the distributor around by 180 degrees?

[Fast Ivan]

Checked your valve clearances?

[Andy 5]

I have checked that the distributor is in the correct way around with the vacuum advance diaphragm on top and that the ht leads are on the correct way around, i will check the valve clearences in the morning, is it 0.3mm for the valve clearences?

I have also taken out the spark plugs and tryed them indervidualy by earthing them on the block and turning it over, and they are all giving bright sparks on all of the ht leads

Edited by Andy 5, 30 July 2015 - 09:29 PM.

[Jon937]

Are you using points or an electronic dizzy?

[Andy 5]

I have converted it to electronic using the accuspark kit

[Tamworthbay]

Have you tried swapping the leads over? I was helping a mate with his when it was running rough, the coil had gone and we replaced that but it still ran rough. Turned out a guy where he works had had a play and got the leads on mixed up. It was rough as anything then perfect when we put them back right (as you would expect). Beyond that I would get a known good cap, don't assume the new one is fine, and then go back to points and condenser and see if that makes a difference. Points ignition is a bit Stone Age but much easier to diagnose than a leccy module. I use accusparl kit and love them but like anything they do fail sometimes.

[Icey]

new mini sport gold coil on to make sure that there is a strong spark

 

Hold the phone.

 

What coil? What's the part number? There are specific coils for electronic ignition (assuming a 65d distributor).

[Andy 5]

This is the coil that i am using - http://www.minisport...ition-coil.html
 image.jpg   60.52K   0 downloads
And this is the electronic conversion kit that i fitted - http://www.ebay.co.u...=item2c61bd328b
 image.jpg   42.21K   0 downloads
And i think the distributor is a 59d unit, please correct me if i am wrong
 image.jpg   66.07K   1 downloads

[petey81]

new mini sport gold coil on to make sure that there is a strong spark

 
Hold the phone.
 
What coil? What's the part number? There are specific coils for electronic ignition (assuming a 65d distributor).

He is using an accuspark one so all ok.

[sledgehammer]

As tamworthbay says - swap the leads 1&3 , see if they fire up

 

if everything else is ok

 

as above - new parts can be faulty - esp a dizzi cap - only needs a scratch / crack to set off a short

[Icey]

 

 

new mini sport gold coil on to make sure that there is a strong spark

 
Hold the phone.
 
What coil? What's the part number? There are specific coils for electronic ignition (assuming a 65d distributor).

He is using an accuspark one so all ok.

 

Of course, helps if you read the previous posts properly.