525I 1991 dies sometimes at Idle
Hello, I've searched the forums over several weeks while working on my issue and while symptoms have improved, the problem of dieing still happens at stops sometimes. Looking for some ideas before I get stuck paying to have it looked at.
Bought this from a friend who replaced the head due to a blown head gasket/cracked head. It recieved all new cooling system at the same time. It also received a new O2 sensor after he checked the code that kept coming up after it was all together which I would expect after having antifreeze go through the exhaust, that ruins a 02 sensor right away.
It has and still does have a 02 sensor code the keeps tripping. It had a constant surging at idle but never died when I got it. I found several vacuum leaks that I fixed which helped smooth the idle alot but still had idle issues. Then pulled the ICV and cleaned it which also helped. It still dies every once in a while but idle is fairly constant until it dies.
When it dies it almost is like a miss and cuts out. Sometimes if it doesn't die but has the miss sensation it will actually surge the Idle speed up several hundred RPMs then come back down and stay around the normal 750.
It doesn't always do this at every stop but at least a few times everytime it's driven.
The RPM really doesn't move around on the tach so it's really close to being ok. If I get figure out what is causing it to die I'll be happy.
Could the Cat be plugged and causing issues like this. Maybe the blown head gasket pushing through coolant plugged it? Could the 02 sensor be ruined quickly and be the cause if the vacuum leaks and ICV weren't fixed when replaced.