Dirty plugs

[southgate]

Been keeping an eye on my spark plugs and have noticed that cylinders 5+6 (2 nearest front screen) plugs are black compared to the others.

I know this must mean its running too rich on those cylinders, but why just those???

[nelly1]

Weak spark or poor compression.

The first possibility would be the coil, as it fires cylinders in pairs.
This is the cheapest option, as a new coil is only 70 quid - see here....

The next possibility is the head gasket or valves affecting those cylinders.
A compression check will tell you the good / bad news!
If the compression is down for these cylinders, sit down and prepare yourself.......

[Basil Brush]

Is that the end of the airbox that the carbon canister vents into?

[southgate]

Basil Brush said:

Is that the end of the airbox that the carbon canister vents into?

Yes I think so. I have been smelling stronger whiffs of petrol recently come to think about it.
Could there be a blockage do you think?