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.