I can remember reading something in the forums about a process which the engine management system runs periodically (possibly to do with removing carbon build up in the engine). There was mention about poor running and increased mpg whilst the process was running. I guess I witnessed this the other week during my daily 70 mile commute as it ran like a bag of ****!!!. Can someone explain what this is all about and point me to the posts which discussed this. I cannot remember the subject of the posts I read but I seem to remember a 3 letter abbreviation (like EGR or DPF) but may have been something else.
My car has done 33k.