wonder if anyone can help me please I have a vw touran sport is it the pd engine I've been told 05 plate . It started running lumpy so the aa came out and without checking anything he said it was a burnt valve ??? Then another garage told me it's the injector seals ??? Then I've not been convinced I've look up YouTube etc about checking the air mass sensor so I brought a new one fitted it and it seems like the mass sensor isn't doing a thing same symptoms plugged and unplugged is there a fuse to this ?