Many times I've said on here there is no known substance that will dissolve carbon. This is still true.
However, the boffins have come up with a system that will clean up the entire fuel system of a petrol car (at least) without dismantling, INC. the CARBON.
It involves disconnecting the normal fuel system, substituting another one using "special" fuel which contains -ve ions that attach to +ve carbon ions in the whole system, including injectors.
It also involves running the engine in this state for an hour at idle plus 50%.
Specialist engineers can do this for you, and it is claimed involves spending £70 or so.
It seems to make a dramatic reduction in unburned hydrocarbons as indicated on the exhaust gas analyser, reducing a 'fail MOT' situation to one tenth or so, therefore a 'pass'.
I simply pass on to you this information, I know nothing else about it, the idea is very new.

Leedsman.

 

Irish - I first saw it on the XK8 episode of WD with Ed China about 2012[ish] Unless you failed a UK emissions test or have bad blue smoke I see no point although any high mileage might well benefit in terms of MPG.

Dealer instruction video here at