Can anybody solve this riddle !!

I'm a bimmer for more than 10 years I have an E46 2000 with M52 engine Recently my car showed more fuel consumption , I thought it's the age or something but after no long time when I start the car it won't start !! the engine rpm goes up and then drops quickly I checked the ICV and cleaned it and got nothing,, after some trials I realized that the engine can start after the third or the fourth ignition trial then the engine is hesitated for 3-4 seconds and behaves as if one of the spark plugs is not working then it goes just fine.

I used the OBD scanner got codes of a faulty Crank positioning sensor, Miss fire and a faulty oxygen sensor
after a week with this mess I ran the scan again found same codes except the o2 sensor which I think it throw the code from the first time bad ignition !

the main symptoms are :
1-There is an obvious loss in power that I feel that the belts doesn't rotate with their full speed,even when going on steep ground or a garage i need to pump more fuel
2- high fuel consumption
3- some times when pressing the gas pedal while ignition to increase RPM the red battery sign in the cluster glows for 2 seconds then turn off
4-Hesitated engine while Idling

Share your thoughts with me please ,, seems like a tough job to do

Vanos?

High fuel consumption is symptom of bad oxygen sensors. pre-cat oxygen sensors (in exhaust manifold by engine) usually die around 100,000 miles. If you're getting a code and they haven't been replaced, probably time to replace them. At the age of your car, if you're getting crank sensor error, I'd replace that too.

Misfires - how old are spark plugs? If more than 60k miles on them, start there, then you might need to test for dying coil packs. Usually you change the misfiring coil to another cylinder and see if the error code follows it to isolate a particular coil.

EDIT - if you are just having to press the gas more like it's not getting enough gas, you could be looking at a clogged fuel filter or dying fuel pump. Fuel filter is a 60-80k miles maintenance item. Fuel pumps average 8-12 years of reliability.

I was thinking of a fuel pump or crankcase ventilation valve , anybody agree ?

Did you change the crank sensor?

I would guess fuel pump and / or oxygen sensors.

Changed the fuel pump and the CCV and nothing happened :S I'll go for the cps

Originally Posted by BUZZ_PLUS

Changed the fuel pump and the CCV and nothing happened :S I'll go for the cps

Oxygen sensors !

intermittent crankshaft sensor. My '01 330i (M54 engine) with 143K miles since new never had O2 sensors replaced. I can't imagine they could last that long. So, my intuition is that the oxygen sensor does very little from normal operation.

I wouldn't be so skeptical as you. Oxygen sensors provide valuable feedback to control fuel/air mixture for proper running and good mileage.
I'd guess yours are working better than zero. Get a live reading of their function to explore.

Relief your self guys it was a cracked cylinder head and it had its effect on all sensors A/f mixture and water consumption, I fixed the problem though wiped out my pockets and its working fine now