Stumbling/misfiring randomly (usually when cold)

[ILoveMPower]

As of late, in the freezing new england weather, my m30 has been stumbling, almost like the power is being cut off completely. The first occurance was on the highway in 5th gear, and it was so unexpected and quick I assumed that I had accidentally blipped the clutch in and out without paying attention. The next morning as I left for class it stumbled really bad in first and second, took almost 10 seconds just to get to a reasonable speed to shift to 3rd.

Is this just plugs + wires or could it be something else? Do I have an intake leak or something? Sorry for asking simple questions but its about -10 with windchill today and I want to be outside for the shortest amount of time possible

[BillionPa]

ice where it shouldnt be, melting and getting in places they shouldnt be?

[Dave M]

If you can rule out the simpler (vacuum/intake leaks, plugs, distributor etc.), then take a read of this (http://www.bimmer.info/forum/showthread.php?t=30111&highlight=solved). Never nkow, maybe the same thing.

Good Luck,

Dave M

[Paul in NZ]

dizzie cap is my guess

[Podmore]

I'd check plug and coil leads and distributor cap. Any hairline cracks in the cap can trap moisture and cause tracking (the H/T current shorts out inside the dizzy cap instead of going down the plug leads). My 535 developed a similar fault, turned out to be the coil wire at the distributor was all but burnt through and corroded into the dizzy cap. New leads and cap fixed it.

[ILoveMPower]

Had a slight rip in the intake boot, duct taped it up (still haven't had time to unhook the battery and reset the system) but as of yet the stumbling problem has ceased (at least for now)

Could this have been the problem?

[535IGeek]

I'm new to the forums, but have a good working understanding of the 535i. My car has 255K miles on it and I have rebuilt just about every working part on it including rebuilding the engine. Well your plugs & wires will not all the sudden stop working, not likely. If you car does not idle very well or idles rough, then its probably a vacuum leak (Pull the dip-stick to see what I mean.) If your car idles ok, but has trouble while driving it may be the fuel pump. If the car has problems starting, it could be the fuel pump and/or the Crankshaft Reference Sensor. The reference sensor is the life/blood of the ignition system. Let me know if you have had any luck and/or have additional clues.