Its a very easy DIY job. Aint involve something very mechanical. I performed this DIY on my car which is a BMW E36, 316i with M40/42-16 Engine. My car was having this little problem of uneven idle/erratic idle/hunting means in idle state the rpm keeps on going up and down which at times causes engine to shut down, which most of the times is quite annoiying to turn it on again. I asked many people what could be the problem most of the people suggested it could be due to O2 Sensor, some suggested to check my MAF(Mass Air Flow Sensor), FPR(Feul Pressure Regulator) and some other sensors. But after much research I got to know that it might be Idle Control Valve, so lets give it a shot. Idle Control Valve or in short ICV regulates the air flow during idle. As when car engine is hunting or rough idling, it means at times that idle control valve is dirty or got carbon in it, as an internal part of the ICV that is called gate gets a bit obstracted to move freely. I dont know as its present ther in Carby setup cars or not but in cars with EFi usually an Idle Control Valve is ther. It gotta pipe connected with air intake duct and a pipe to intake manifold. It gotta wire connected to it which sends it signal to ON and OFF the gate and electric current.
So, at the start of this week I got Eid holidays, so one afternoon when I got up, I thought its quite a long time since I am postponing this process so lets get on with it.
Here it goes.
Remove the ICV.
Unscrew the clips of hose pipes and gently take the wire jack off the ICV. Then twist the hose pipes a little and remove the ICV.
Clean the ICV
ICV's gate should be black due to carbon and thanks to our leaded feul. One needs to clean it up in order to get the gate open and close smoothly. Firstly, put some cotton towel inside it and try to clean it, then put some alcohol or spirit or nail polish remover in it and shake it so that all the carbon gets liquified. Then try to clean it with the help of some cotton buds. Do remember to clean both ends. Let it dry for an hour then spray some WD 40 in it. Do not put liquid on the terminal. It should be shing inside after getting cleaned.
Then clip the hoses and connect the jack and probably your idling will get better. In my case the problem is over nowand my car revs excellent on idling. Btw, do keep in mind ther could be other reasons aswell for rough idling.
Thnxx..
P.S. Thanks to Storm as I got motivated to make myself a bit dirty after going through his DIY topic. And to my fellow pals at bimmerfest/bimmerboard, who contributed in increasing my understanding of my bmw. People presume that its a difficult car but after couple of DIYs and such jobs I concluded that they are quite easy rather more easy then a Japense counterpart. Firstly, they are spacious, secondly support on internet is immense, thirdly everything is in detail and properly engineered.