bmws and any openings such as the orings on the dipstick will create an unregulated vacum leak that will have an effect on the idle., In a case like yours where you have installed a mass airflow sensor instead of the afm I would guess that you're probably using a hotwire mass air flow sensor, if thats the case then if you check on most cars equipped with hotwire sensor they have the tube from the valve cover downstream of the mass air flow sensor, this is to keep any oil mist from contaminating that hot wire sensor... If it were mine I would move the sensor closer to the air filter and then connect the hose from the valve cover as far downstream as I could get it, maybe a couple of inches in front of the throttle body....











Quote Originally Posted by 535ise
Sorry for the dumb and slightly off topic question but what's the connection between an (intake) vacume leak and a crank case leak(dipstick o-ring's) ?

The reason i ask is because i use an oil catch tank rather than venting the fumes back into the intake below's and was wondering if I was doing some thing wronge ?

(This picture was taken before i tidied the wiring up)



Cheer's

Andy