Here is the finale!
I know there are a lot of people out there wanting an update, now that winter is slowing down I can drive the z3 again. I've fixed the rough idle/ hesitation/ flat acceleration.
Ok, here goes. the final contributing factors are:
Crazy Idle: The idle jumping up and down, I posted a video showing how bad it was.
The Fix: Replaced Mass Air Flow Sensor.
Hesitation: The car would stumble and jerk.
The Fix: Fuel Pump.
Rough Idle: I had a misfire pending on cylinders 1, 2,3 and 4.
The Fix: Coil Pack and Valve cover spark plug tube grommets for the oil leaking on plugs.
Random Power Cut Outs: The car would suddenly lose partial power.
The Fix: Camshaft Postition Sensor.
These were the Parts that did the trick; although, I replaced a lot more sensors than this.
Thanks to everyone who followed and helped me on the road to fixing this. Expect more DIYs soon!
I am not discouraged because every wrong attempt discarded is a step forward.
A little Experiment
When my idle got soo bad it was making the car rev up and down, it made me aware that this became a sensor problem. I unplugged my Air mass sensor to see what would happen. Lo and Behold the idle smoothed out, I still had an odd hesitation. A new fuel pressure regulator solved this, please remember to use a BMW FPR, an aftermarket will not work and will most likely cause an engine code.
Although I haven't tracked down the rough idle yet, I've recently read a 93 page thread about rough idles and hesitation.
I've replaced all of the main things that cause rough idle and have yet to perform a Leak down or compression test.
After narrowing down the possible causes, I've come to the conclusion that:
It may be another vacuum leak somewhere
It may be my rear O2 sensor
It may be my Crankshaft position sensor
It may be something internal
After replacing and researching parts, I came to the conclusion that everything I was doing was not fixing the issue and it must be something else.
I've heard theories:
Lower Oil weight to 5w-30 and it will smooth out idle
The M44 simply always rough idles
Vacuum leaks are always the cause of rough idle on the M44
The ignition components used on the M44 are a poor design
The fuel pump causes rough idle before it fails
The cam position sensor is the problem most of the time
When I bought my Z3 in the beginning of March 2012, it developed a rough idle. I was determined I could track it down and began throwing parts at it.
List of Parts: