BMW Repair: Check engine light comes on & off, mass air flow meter, mass air flow

Question
When engine is idling , the check engine light will come on.When it is in park or when I give it gas the check engine light goes off. The engine runs fine when driving. Sometimes when I start the car in the morning the rpm gauge fluctuates.After some minutes it runs smoothly. The air filter housing has a hole in it, will that cause the problem?  I covered it up with tape, will I need a new one? I just bought a new air flow mass, it runs better sometimes, but the engine light still comes on.
I have a 1993 BMW 318is 2 door coupe. 4 valve 1.8 liter.


Answer
Hi Darryl, Sounds to me like your engine runs rough when cold and after it warms up it runs smoothly correct?  If that is the case, then that is caused by an idle control valve or idle control motor.  And what that does is it controls the amount of air that goes into the intake when idleing.  Especially when cold.  The best thing to do is take it to a shop and ask someone to just unplug it when it the engine is cold and see if it makes a difference the way it idles.  If it does not, then you know that is not what the problem is.  It could also be an idle speed sensor going bad.  It's really hard to tell without actually seeing the car and pluging a scanner into it to pull codes.  Another thing you can do your self is take a spray bottle with water in it and spray around the intake manifold and vacume hoses and the hole in the air filter housing.  That will tell you if there is some kind of vacume leak which can cause it to idle rough.  As far as the hole in the air filter housing, as long as it is before the mass air flow meter then it shouldn't make a difference.  But if it is anywhere after the mass air flow meter then that too can cause it to run rough.  But in my experience working on different types of cars with those symptoms, it's usually the idle control motor or idle control valve as some people would call it.  Especially if it does when it's cold.  Think about it.  When the car is idleing the check engine light comes on.  When you give it gas it goes off because the car is no longer ideling. And then when you come off the gas, it goes back on when the rpm's kick down.  Bare in mind though, this is just an assumption that I am giving you without actually seeing the car.  I could be wrong.  It's best to have someone pull the codes off the computer to really determine the problem and that usually runs about $45.00 at any shop and $1000 at bmw dealership because they are ridiculous.  But it is a good place for you to start and it's pretty cheap.  Now for the air filter housing, the best thing to do is take the tape off and go to any auto parts store and get some rtv silicone gasket. ( MAKE SURE IT IS NOT THE KIND THAT WILL HARM SENSORS.)  They make silicone that is sensor safe because some silicones will damage the mass air flow meter and the o2 sensors.  Just take the silicone and spread it over the hole and let it dry.  If you want you can take some black touch up paint and paint it to kind of cover it up a bit.  In expensive way of fixing it.  I hope this helps you out.  Let me know what the out come is.  Good Luck....Rahim.