device on top of inlet manifold

i have a bosch device sits right on top on inlet with pipes going into plastic air intake..it runs constantly even when car is switched off...it is connected either side of throttle body..ive tried disconnecting electrics but then car wont start..anybody had the problem /what is it doing.and why

i should add its on a v8 4.6 petrol 2000 circa

Photo?

From the description and without checking on mine because it;s****ing down!! I would say it sounds like you ar on about the idle sensing valve, if it is you should not have it doing anything whilst switched off, in fact I can't think of anything that should/does run there whilst switched off???

If it is the isv it is about 3" long and 1.5" dia round? take it of and give it a good clean inside with brake or carb cleaner, they do get gummed up inside and stick, perhaps it is stuck and causing some upset??

like just said...... picture......

Steve

yes you are right its the idle control...some one as jury rigged it so it runs all the time and is turned off and on by a seperate switch...im not too good with electrics so i may be some time...thanks for replies