Drivability and OBD Codes Assistance Requested
 

Hello All,

I have a 2010 BMW 535iXT (N54 engine) with almost 100,000 miles. I have a couple of issues I am addressing, which triggered another set of issues possibly. Hopefully someone can show me what I may have done incorrectly while I was "fixing" my car. I do have Bentley manual, code reader and am researching OBD codes, etc but I don't have any OBD experience and minimal context.

Scenario: Two years ago I had a catastrophic failure of the electric water pump. As I was away from my home area, I had the dealership address it. They exchanged the electric water pump, but NOT the electric thermostat or the silly, PIA short hose connecting the thermostat and water pump. Car drove fine since.

Now that I am pseudo-retired, I am more engaged in doing my own maintenance. I noticed the ubiquitous oil leaks from the oil filler/oil cooler gaskets and decided to address them. "While I was there" I also wanted to address replacing the serpentine belt, tension adjuster and the two idle pulleys. I also figured I should replace all the primary coolant hoses and a new thermostat. Replacing oil filler/cooler housing gaskets involved taking off most of the air plumbing and intake manifold. Everything seems to have been put back in place correctly, and torqued down. I changed O-rings where I did not replace hoses.

I finished the radiator hoses, overflow container, serpentine belts,pulleys… etc. I bled the coolant system. Most of the car is re-assembled, minus the cowling and radiator covers and the beauty cover. Car started fine, almost immediately started a mild, intermittent misfire which increased in intensity and repetition. Car showed an orange engine with a cross bar over it and the limp mode started.

SITUATION: I am a firm believer that if something seems to go wrong with your car when you are "fixing it" then it is probably from some unexpected change you instituted. I have a brand new Foxwell NT301 scanner/reader. I have NEVER used any code reader before. Here's the readout.

$7EC - No modules reported

$7E8
P052B Cold start A Camshaft Positioning Timing over retarded bank.
P0304 Cylinder 4 misfire

I/M
Mil - shows lightbulb
DTC shows a red two with a circle around it ($7Ec and $7E8?)
Ignition shows "Spark"
pd DTC shows orange two with circle around it
Air shows a circle with diagonal red bar
EGR shows a circle with diagonal red bar
HCAT shows a circle with diagonal red bar

So,,,, anything to check out that might have caused the misfire and over-retardation? Anything I should do before I address before I start replacing coils/plugs/valve cover gasket? Why do I have a camshaft misposition? MAF / VANOS sensor(s) implications? Intake manifold not on correctly? Enquiring minds want to know. Thanks for any assistance you may be able to provide.

Researched the cam sensor / cam positioning timing/over-retarded bank a bit. Two things came to my attention pretty quickly.

One was low oil -- this is probably not the problem as I drained the oil when I replaced the oil filler/oil cooler gaskets and then filled up with 6.5 liters as per Bentley capacity for N54 engines. I ran the engine long enough in the garage for the electronic oil level to be represented as "full" on the display. N54 engines don't have a oil dipstick...
However, the valves sounded louder than I am used to. That may be because the beauty cover was off. It also might mean the valves aren't getting much oil...The engine also seemed to warm/heat up rather quickly, and, as stated, ran rough.

Checked the primary intake manifold 3.5mm hose and it appeared to be good.

Cylinder 4 Misfire: Although I am not a fan of coincidental failure, the valve cover does leak and there is leakage near the 4th from the firewall cylinder. I don't see that any could have gotten down the coil/plug hole. Oil is not in the valley of the hole.

These engines are really loud with the cover off but I find it is those injectors that are so tappety and not the valves.

I have not had the pleasure to work on an N54 engine and I certainly do not know what electrical connectors had to be disconnected from any of the components while performing the maintenance you described. However I would retrace my steps to ensure all connections are solid, connected to the correct component, and not contaminated with water or oil. Good luck.

^this.
Running without the lid, these sound like bad diesels. Ordinary running the sound is sometimes audible too.