92 535i, check engine light at idle

[scoobysmak]

Well it has been a while and I am going to give a little background to that might help solve the problem. Almost exactly a year ago I blew the head gasket in the car, I am sure it was from almost overheating it twice from blown radiator hoses and a faulty fan clutch (it was almost in the red zone on the temp gauge but not quite there). I pulled the head got it milled, and then put a new head gasket on and put it back together. After this I had a check engine light, I ran a computer on it and it pointed to the O2sensor. Since I had ran coolant through the exhaust I figured this was a good place to start, plus with 120k on the car couldn't hurt. Well I tried to replace it and after 15 hours of pain and grief I took it to a pro. He worked on it for about 3 hours before he just cut the old sensor off and welded a new O2 bong on. Well on the way home I noticed a big difference in performace but at idle I still had a check engine light. It comes on after around 15 to 20 seconds at idle 90% of the time, why it doesnt' do it all the time is a mystery to me. Normally it has a tendancy to be cold when it doesnt' come on at idle but has come on when cold. Other symtoms that maybe related is I have an oil leak somewhere, I smell oil cooking like I am pouring a bit on the exhaust manifold but I look and don't see any oil that looks new. I made a mess when I pulled the head off so I figured at first this was just old oil burning off at first but after getting the car hot a few times I figured this would be gone (I have driven the car about a 1000 miles after, its only 7.5 miles to work so it gets rotated between 3 other cars too, yeah I should be shot for not driving it more often). Another symtom is I have "squishy" brakes, the car stops fine but after setting for a second I can still press down on the brake pedal about an inch and a half. Well I am planning on using this car for a road trip and would rather use this car than any other, plus it needs a few road miles. I only mention the oil leak and the brake problem because if I have an oil leak that causes a vacum prolbem it may have affected both. I am not quite sure where to start but hope this information is helpful. Thanks in advance.

[scoobysmak]

Thinking maybe it could be the brake booster causing the problem??? Any other ideas.

[BimmerDude]

I had, what im assuming is the same problem with my 90' 535i the cause was improperly placed vacume hoses, another contributor was a leaking break booster vacume hose. I can post pics within 35 hours if you'd like.
the break booster hose joint was just leaking a bit of air.(it was cracked.)

[632 Regal]

check all intake connections fot leakage, look carefully. as for the oil smell you will have to zero in on the leak. Inspestion should result in the problem.

good luck

[632 Regal]

or low oil pressure.

[winfred]

seen a couple 535s throw a light at idle (one was my car) bad idle control valve on one and bad 02 sensor was the other