I have had this posted to two different Mercedes forums for several days now with ZERO response. Just going to post it on here in a long shot someone on board could help me out. I have a 2013 ML350 with the 3.5L direct injected M276 engine with ~67,000 miles. This is my wife's daily. Here are my symptoms... Round 1: I started getting long crank times to start the car. It would always start, but just took much longer than normal. Ran well...but mileage started degrading. My wife was on her way home from work and car started misfiring badly. No power, engine light on. She was only 2 miles from home so I asked her to limp it home on the shoulder. Pull the codes...lots of misfires, on multiple cylinders. Cylinder 2 and 4 stood out. Also had code P008992 "The pressure regulating valve has a malfunction. The function or the instruction is faulty" Replaced all 6 plugs and coils. Plug on cylinder 2 was totally black. Plug on cylinder 4 was about half as black as cylinder 2, but not normal. The remaining 4 plugs looked fine. Car ran great, I took her out for a good old Italian tune up...purring like a kitten. Wife and I took the car out yesterday...started having extended cranks again. This is less than 50 miles after the plugs/coils. I also was watching the fuel economy, and it seemed much worse than normal. Wife took the car out this morning...had the same problem. Strong mis-fires, but she was in town and limped home. I went out to pull codes this afternoon... Misfires on 4, 5, 6...and P008992 "The pressure regulating valve has a malfunction. The function or the instruction is faulty" I clear codes and start it up and she purrs like a kitten again. Odd. Ok...still a newb to MB, but not to cars or engines. I am guessing this is a pressure regulating valve that is controlling cam phase? Can anybody help? A google search for the code turns up almost nothing... Please help me get my bride back behind the wheel of her Benz before she wants her Beemer back. Thank you!!!!!!!!!