Simon back with us in his BMW 635D for new rear springs, swirl flap delete and a snapped wheel stud removed and new set fitted. We always advise preventative removal on most BMW engines fitted with this flawed unnecessary system that they are deleted. This involves taking out the swirl flaps from the intake manifold usually with a blanking kit and seals. The disadvantages of swirl flaps are mainly associated with carbon fouling by exhaust recirculating gasses , this leaves carbon deposits on the flaps and inside the manifold causing them to stick and display an EML or worse still snap and get ingested into the cylinder head, usually causing irreparable damage.