8 replies to this topic

[stevelane]

Mini city 1992

 

998

 

My engine was recently running lumpy and after a few diagnostic checks I have noticed that it doesn,t fire in cylinder 2. I came to this conclusion by removing each of the spark plug leads and there was no change in the engine sound on this cylinder.

 

I swapped leads over and spark plugs and still the same. I have removed the plug on that cylinder and have earthed it and seem to get a good spark.

 

So next for the compression test to see whether it was head gasket or rings, car had a history of gaskets before the block and head were skimmed. I was expecting the compresssion to be right down on that cylinder but they were all roughly the same, in fact 1,2 and 3 all had 210 and 4 was the only one slightly down with 200.

 

As pleased as I was that the head gasket and rings are ok I am a bit stuck as to where to go from here.

 

Any advice?

Edited by stevelane, 25 June 2014 - 09:19 AM.

[ArneBrys]

- Check the distributor cap

- Check valve operation. Had something similar with a non mini engine (2cv) turned out the be the exhaust vale no longer opened due to a massive camshaft failure.

[stevelane]

Have cleaned up the contact points on the cap and the roter arm and need to see if thats worked, am tempted to replace the cap, leads and plugs just to rule them out.

 

Sorry for my inexperience but how do i check valve operation? I only recently did the valve gaps and both the valves on that cylinder seemed to be moving up and down freely but can double check - do I just turn the engine over to see if they move?

Edited by stevelane, 25 June 2014 - 09:34 AM.

[ArneBrys]

To check the valve operation just check that they open just like when setting the gaps. In my case the exhaust valve no longer opened still giving a good compression reading however not running at all on that cylinder.

 

However i would mostly focus on the ignition as this is most probably the issue here.

[stevelane]

Have checked the valves and the are moving fine. Will renew the cap and the leads, there is a definate spark but really want to rule them out

[stevelane]

Replaced the cap, leads and rotor arm and it started first time with no issues. It was running and seemed very smooth but as a precaution I took the spark leads off one at a time again and now it's not firing in two or four but there is a spark in both

[stevelane]

All done, firing order was set up wrong

[Ethel]

Tough little lump the "A",

 

A compression test is the gold standard for valve function - if you haven't got a gauge stick your thumb over the plug hole for a crude indication.

 

Firing order is 1-3-4-2, the rotor arm turns anti-clockwise with the dizzy cap post nearest No1 cylinder (radiator end) serving the same

 

i.e.

 

31

42

 

as you look at the cap.

[stevelane]

Thanks, I think it was just a lead 1st time but then when I changed it over I mixed up the firing order. Just been out for a run and it seems all good now