2008 X3 N52 Intermittent Engine Misfire

[mikey30]

Just started daily driving my wife's 2008 X3 and overall really like the car.

As I was merging onto the highway yesterday and accelerating, I had a loss of power, the service engine soon light came on and the engine began stumbling. Anything over about 10% throttle and I could feel a very consistent misfire. I drove a few miles on the highway and then as I got off, the service engine soon light went away. I put it in neutral and revved it a few times and everything seemed fine.

It is a little concerning and I was looking for some potential recommendations. The car has about 110k miles. My thoughts on causes were the following:

Spark plugs/coil (Still original)
O2 Sensor
Vacuum Leak

Is there anything else you would recommend checking or replacing? I would like to get another 40k or so out of the car.

Also, I wish there was a little more engine sound. I've seen some removing the "intake silencer" on other N52 cars but haven't heard of anyone doing it on an X3. Any experience with this?

Thanks for the help!

-Mikey

[bmwdirtracer]

Step number 1 is using a BMW specific scan tool to read the codes in the DME (engine computer). Since you have a check engine light, and since the apparent problem is misfiring, there will certainly be "OBD2" generic codes in there also. While Autozone or a similar place will read these OBD codes for free, they cannot read the actual BMW codes, which are far more accurate, and much better at pointing you towards the culprit(s).

Certainly, some basic maintenance replacement parts are always a good idea. Spark plugs should be changed every 50k miles, and I'd generally throw a coil at any cylinder that's misfiring, and by 110 k miles, a whole set isn't a bad idea either. Make absolutely sure that you buy ONLY OEM parts from a BMW specialist supplier. FCP Euro is one of my favorites, and actually has a lifetime warranty on everything they sell.

The "intake silencer" is the factory air filter box. I highly recommend that you keep this intact. It's not only a much better air filter than aftermarket cone things, it also prevents water ingestion.