One thing I forgot to mention was to check your oil cap(the fill cap on the valve cover). I accidentally twisted it on crooked before and the car wouldn't idle, it felt like it was running on three cylinders. The next thing I'd check would be the CCV. This is a round plastic disc located just behind the intake manifold on the driver's side. When those get clogged, they tend to hiss. Have you noticed a hissing sound? Those two things are just random guesses, but not likely the culprit.
The fault codes generally point you in the right direction, but I just wanted you to check those things before you invested money in new parts. When you replaced the plug wires, did you install them one at a time or did you remove all of them and replace them at the the same time? Is it possible that two of the plug wires got swapped onto the wrong cylinders? They should be different lengths(longest goes furthest short goes closest etc).
If those three things are good(oil cap, no hissing from CCV, plug wires in correct order), then I think it would be safe to assume the ICV is bad since you cleaned it and it didn't seem to help.
Don't quote me on this, but I seem to recall reading somewhere that you can check the MAF by unplugging it. If the idle levels out while it's unplugged, I think that indicates a bad MAF. I could be wrong though, so you might want to investigate that further.
And finally, the cat. Cats usually fail in one of two ways. Either they get clogged up or the honeycomb monolith inside rattles loose and blocks the air passage. Some people report that their exhaust smells like rotten eggs when the cat fails. BMW had a recall on the cats, but it expired a few years ago. So that's a bummer. I'd clear the code and see if it comes back. Like I said, cats are very expensive and most aftermarket cats don't work on OBDII BMW's. There was one member that that claimed to have good luck with an aftermarket cat, but I can't remember who it was or what brand they used. But IIRC it wasn't a cheap one, it was still pricey.
Hope that helps, and I wish you the best of luck getting things sorted out. |