[E70N52]

I have a 2008 BMW E70 with the N52 motor. I recently bought the car with around 127k miles. I got the car for cheap due to a stripped drain plug. PO states the car was taken to an oil change shop where they stripped it and shut off the motor immediately upon realizing the oil was leaking out. After helicoiling the drain plug I filled it with oil and tried to start it but the battery was so dead from it sitting for a couple weeks, it wouldn't start. I left the battery on the charger overnight and tried again the next day. The car cranks fast but will barely stumble and only sometimes sputters. The few times I have gotten it to start it sounds like it is running on only a few cylinders and the exhaust smells super rich. If it does run it may idle badly for 30 seconds then shut off on its own. No codes present when it does run although intermittently it will give an intake VANOS code. Here is a list of things I have checked so far:

• Replaced spark plugs
• Checked spark on each coil pack
• Checked fuel pressure at the rail
• Checked operation and spray pattern of each fuel injector
• Checked operation of throttle body
• Reset all adaptations using Protool
• Valvetronic relearn using Protool
• Checked for rodent damage in DME box
• Checked intake tract for blockages
• Unplugged MAF
• Unplugged valvetronic motor and manually turned it open to see if it would idle off the throttle body
• Checked ground strap
• Checked compression

With all these things I have tried one of my next guesses is the DME being bad. The voltage was super low when I jump-started it the very first time and I'm wondering if the large swing in voltage could have damaged it. Is there any way to tell if the DME is damaged? I visually inspected it by removing it from the case, but am tempted to send it out for repair or try to find a used one. Any help is appreciated.

[E70N52]

SOLUTION: So after dumping oil down each cylinder to try to up the compression, like multiple people suggested about 5 or 6 times I decided this was not raising the compression at all and decided to keep diagnosing beyond that as to find the actual reason why the compression is low. After leak-down testing each cylinder and getting almost perfect numbers, I decided the timing must be off, causing the valves to start to open during the compression stroke. Since it's a relatively easy engine to time I decided to buy the timing tools and check it out for myself. Upon removing the valve cover and locking the crank the timing was about 45 degrees off on the exhaust camshaft. Using a borescope, it was clear the valves just kissed the tops of the pistons, but they must not have made enough hard contact to bend, since the leakdown numbers were good. After properly retiming the engine, it did fire up almost immediately. My theory is that when the engine was run without oil briefly, the hydraulic tensioner lost pressure the chain skipped. Still running a little rough due to all the oil in the cylinders burning off, but it should clean up after a little bit of driving.