BMW Repair: 2002 530I, valve lifter, faulty valve

Question
HI, I OWN A 2002 530I AND RECENTLY WHEN I START IT IN THE MORNING OR AFTER SITTING FOR A SEVERAL HOURS, THE ENGINE RUNS ROUGH AND THE CHECK ENGINE LIGHT CAME ON. THIS ONLY HAPPENS WHEN FIRST STARTED IN COLDER WEATHER AND VEHICLE IS NOT MOVING. IT HAS NEVER HAPPENED WHEN DRIVING OR ENGINE IS HOT. I TOOK IT TO MY LOCAL DEALER THEY SCANNED IT AND TOLD ME THE CODE WAS P1351 WHICH THEY SAID WAS BASICALLY A MISSFIRE IN NUMBER 5 CYLINDER DUE TO FUEL CUT OFF. I SPOKE WITH THE TECH AND HE TOLD ME HE HAS HEARD OF THIS BUT NEVER HAD TO REPAIR AND THAT TECH SUPPORT OR SOMETHING IN MONTREAL HAD TO REPAIR ONE ONCE WHICH ENDED UP BEING A WORN ALTERNATOR BELT CAUSING THE TENSIONER TO MOVE AND MAKE VIBRATIONS WHICH IN TURN CAUSED THE COMPUTER TO SHUT OFF FUEL TO ONE CYLINDER. THEY INSPECTED MY BELTS AND THEY WERE CRACKED AND WORN, SO THEY REPLACED THEM AND TOLD ME THEY HAD TO START FROM THERE AND I COULD POSSIBLY HAVE A FAULTY VALVE LIFTER ALSO CAUSING LOW COMPRESSION AND FUEL SHUT OFF. HE ALSO MENTIONED THAT THIS ENGINE WAS BAD FOR LIFTERS. I COULD NOT HEAR ANY NOISEY LIFTERS. I ALSO FIND THE ALTERNATOR BELT REPAIR IS HIGHLY UNLIKELY TO BE THE FAULT. I HAVE OWNED THE CAR FOR 8 MONTHS AND NEVER HAD A PROBLEM IN THE SUMMER BUT NOW THAT WE ARE APPROACHING WINTER IT SEEMS TO BE GETTING WORSE. ENGINE HAS 80,OOO KM'S AND THE LAST SEVEN OF THE VIN IS CK26576 HAVE YOU COME ACROSS THIS PROBLEM AND IF THE LIFTERS ARE THE CAUSE DO I HAVE TO REPLACE ALL THE ENGINE'S LIFTERS OR JUST THAT EFFECTIVE CYLINDER? ANY OTHER IDEAS? THANKS AND SORRY FOR THE LONG STORY, CHRIS.

Answer
Chris the Belt theory is a load of .... Second the misfire is causing fuel to be cut off of that cylinder. The motor electronic controller (DME) won't inject fuel into a cylinder that it detects is not firing. Not the other way around. That may have been a misunderstanding. I would start by swapping spark plugs to a different cylinder and ignition coils to a different cylinder and clearing faults. Much less common are fuel injectors, you can swap those around too. See if the fault returns to that cylinder or travels to another cylinder. I would also check the camshaft position sensors (intake and exhaust sensors) for the updated style sensors (old style will have a stepped nose and the new style will have a more square nose). If you have the older sensors and you replace them and the problem continues, don't feel bad they would have failed eventually. The reason I say check these is that your symptoms are inline with faulty cam sensors but they almost always throw a fault with their name on it. Not just a random cylinder misfire. Hydraulic lifters can cause this but they usually make lifter ticking noises if the oil has bled out of them as you said. If this problem is reproducible then take a cold compression test and compare cylinders readings. Figure out what is happening in cylinder number five. You can replace just cylinder number five lifters (four of them). If you take the valve cover off and the camshafts out you can see which lifter has bled down by the amount of space and play in it compared to the others. Have them do some checking and make sure Ignition and fuel are okay before condemning the valvetrain. Not to say that you cant look at compression or cylinder leak down.
-Evan