UK-POLOS.NET - THE VW Polo Forum

Hi

My car was stood for a while and needed some work. Had it all done and booked for MOT on Tuesday but concerned it may fail emissions due to rough idle. Changed the coil pack, had a full service with new spark plugs. Exhaust is fine. Had some leaks but all welded up nicely now. It sits at about 800rpm on idle but sounds more like a diesel than petrol lol. Not an extremely rough idle but was much quieter before. Any ideas what it could be?

Most common rough idle problem for these vehicles is a clogged crankcase breather hose, PCV valve and/or EGR. The breather hose is on the left side of the air filter and goes down to the PCV (positive crankcase ventilation) valve on the back of the engine. The EGR is located on the right front side of the engine and goes through a pipe/hose towards the back of the engine. If one (or both) of these is clogged with muck or sludge it makes the engine run like crap. If you want more detailed information search on youtube for 1.4 'crankcase breather', 'PCV valve' and 'EGR'. Good luck!

Thanks for the advice. I’ll give it a try. Much appreciated.