Carbon removal from exhaust valves without dismant

[lowtechguy]

Backround
I had fitted a faulty throttle body by mistake (Idle control valve was broken) and as such have coked the engine.

I took the car for a mot and it failed on the emissions only just (should be 0.3 on the fast idle and was as high as 0.90 but as low as 0.45).

My question is what can I do to remove the deposits on the exhaust valves without dismantling the engine?

There are many products that claim the world such as power boost, redex and so on. I have been recommended Forte gas treatment from a local tuner but I wondered if any of you had any products you had good experiences with or perhaps another technique such as filling the spark plug holes with something and then turning the engine by hand or something?

Many thanks,

Cristian

[pnl]

In days of old when Knights were bold we use to whip out the plugs and pore an egg cup full of redex down each plug hole ..let it soak for a couple of days and turn over the engine with a rag over the plug holes befor re-fitting the spark plugs..stand well back and have the fire brigade on standby.. by god it shifts the coke I tell you ..cough cough..