If your at say 40k+ mileage and already have a good build up of carbon, it will clean them abit but never properly get rid of it. The only option is to manually clean it.
This was after using a carbon build up cleaner spray and as you can see it barely did nothing. But luckily I was planning to to fit a new intercooler and RS4 fuel regulator valve, so thought I might aswell clean them manually, while I have everything off anyway.
This is valves/port 2-3 hours later with carb and brake cleaner, wire brushes and cotton buds.
Getting the inlet off isn't hard, but just time consuming getting everything off. I did have the luxury of having the whole front bumper, radiator and front end taken off so had easy access to everything. I'd say the hardest part would be getting the throttle body on and off and the throttle pip as its very tight between the radiator fan and engine.
And it does make quite abit of difference, as now my leon idles much better, does slightly better mpg and I gained around 10BHP (had a dyno run before and after)
If you have a spare weekend and are fairly good with tools, its a simple but time consuming job.
In the end it cost me £20-30 in cleaner and wire brushes and about 4-5 hours and another £10 for a new terminal plug which I snapped the clip getting it off the DV valve
There's an excellent guide on this forum somewhere for it, but forgot the link. Really useful and pretty much a step by step guide and covers everything.
If you remember where this thread is I'd really appreciate it as it's something that would benefit my Cupra as she is at 48k now so no doubt needs it.
Cheers
