My 2003 BMW 745Li is cranking but not starting. The engine is cranking without making any unusual noises. There is no rumbling or un-evenness in...

My 2003 BMW 745Li is cranking but not starting. The engine is cranking without making any unusual noises. There is no rumbling or un-evenness in the cranking to suggest that there is any attempt at combustion in any of the cylinders.

The car was running well a couple months ago but burning oil due to bad valve stem seals. I replaced the valve stem seals using the AGA N62 Valve Stem Seal kit: Removed the variocam motor, disconnected electrical connectors and then removed valve cover then used the tools in the kit to replace all 32 valve stem seals without removing the cam shafts or touching the timing.

After reassembling everything, I reconnected everything, hit the ignition without starting the car and waited for 30 seconds, turned off ignition and repeated that process twice. I then checked the DME for any codes and cleared them. There were a number of codes related to the variocam motors and throttle body potentiometers: 2786 DME: Throttle-Valve Potentiometer 1 2787 DME: Throttle-Valve Potentiometer 2 2866 DME: Variable Valve Gear - Learning Stops Necessary 2865 DME: Variable Valve Gear - Power Limitation In Limp-Home Operating Mode 285A DME: Variable Valve Gear - Monitoring, Servomotor, Bank 1 2863 DME: Variable Valve Gear - Voltage Supply, Power Output Stage, Bank 2

I cleared the codes, tried cranking again and the same codes reappeared. I disconnected the electrical connectors for the variocam motors, eccentric shaft sensor, cam position sensors and throttle body; and gave them a bit of a cleaning with electrical contact cleaner and compressed air. After reconnecting, clearing the codes, making sure the battery was fully charged and then cranking again the only code that reappeared is 285A DME: Variable Valve Gear - Monitoring, Servomotor, Bank 1. There is no change in the behavior of the engine though - it still fails to start.

I've checked that the key is being detected - it displays the "key is recognized" message when the key is inserted so I don't believe it is the immobilizer.

I've also noticed that when I insert the key, the throttle body appears to be trying to adjust itself but it only moves from very slightly open to closed and it makes a high pitched whining noise while its trying to move closed. When cranking the engine the throttle body remains closed.

I've also checked that I have fuel at the fuel rail by gently poking the schrader valve to check for fuel spraying out. And I've confirmed the fuel pump fuse is okay and I can use my scan tool to manually activate it successfully.

The engine was running well prior to me doing the work, and I did the work using a leak down tester to hold the valves closed so I had compression after I replaced the seals and reinstalled the rocker arms. The only things installed/touched after that point to my understanding would have been the spark plugs, spark plug tubes, valve cover, valve cover gasket, eccentric shaft sensor, eccentric shaft sensor gasket, variocam motor and gaskets, vanos solenoids and orings, cam shaft sensors and orings and all the connectors.

285A DME: Variable Valve Gear - Monitoring, Servomotor, Bank 1 is the only code currently present. I've tried starting the car and this is the only code that gets set. There are no pending codes either.

I didn't remove the eccentric cam shaft. I just worked between the small gap between it and the intake shaft. I verified the rocker arms and intermediate rocker arms were all in position and I rotated the engine a few times to make sure they were all moving correctly prior to reinstalling the valve cover.

I did a leak down test on both banks and none of the cylinders appear to have compression. The air seems to be leaking into the intake. Is it possible that the valvetronic system is holding the intake valves open because its out of position/not properly calibrating? I can't imagine there's something mechanically wrong with the engine because it was running fine prior to the work, and I confirmed I had compression after I reinstalled the rocker arms. Plus if I made a mistake, I could imagine one or two cylinders having issues but certainly not all 8. The car is also reporting 9.6mm lift on both intake valve banks which from what I've found online might be maximum lift for the variocam system?

Finally - I probed my cam shaft sensors and confirmed battery voltage (12.4+ V at each of them on their power feed), I also picked up between 0.5V and 11.8V on the reference line (multiple readings between rotating the engine by hand). I'm used to expecting 0V to 5V on these types of sensors. Is it normal to have 0 to 12V? 

Also just in case it helps provide some insights, I gathered the following data from the car:

Lift inlet valves bank 1: 9.6mm

Lift inlet valves bank 2: 9.6mm

Adjustment angle 0 degrees

Minimal valve lift 0mm

Vanos position inlet bank 1 120 degree

Vanos position inlet bank 2 120 degree

Exhaust on both banks 120 degrees

Vanos adaptation inlet bank 1 131 degrees

Vanos adaptation inlet bank 2 134.20 degrees

Exhaust bank 1 76.70 degrees

Exhaust bank 2 72.30 degrees

Based on your comments would you agree with the following plan:

1) Double check the grounds and ensure the valvetronic motor is getting sufficient power.

2) If that doesn't work - is there some way to test the eccentric shaft sensor with my multi-meter? I don't have an oscilloscope.

3) Remove the bank 1 valve cover and verify the rocker arms are all correct. With the valvetronic motor removed, check if I have compression in the cylinders again to at least confirm the issue is with valvetronic and not something else.

Alright. Thanks. I'll give it a try

No that was all. I'll focus on making sure the power and grounds are good. And then try the recalibration if needed from my scan tool.

You can close it out