The day before this happened, my battery died. I assumed it was my fault, I had the engine off but the radio going for about 30 minutes. Pushed the ignition and it drained what was left in the battery, needed a jump. After that I checked all my battery readings, everything was fine.

The next night after a short 4 mile drive from work to home ( I did let it warm up), I pulled in, shut the car off and heard rhythmic thumping, I live on an Army base so I assumed it was just a chopper in the distance per usual. Took the key out, gathered my things, about 30 seconds or so and when I opened my door I could tell it was coming from the engine, so I popped the hood and made the video. By this point it has been going on for several minutes, with no change in rhythm. As soon as I put the key in and gave power to the car, it stopped. It hasn't happened since.

I couldn't tell where it was coming from, or see anything moving, but my engine knowledge is very limited and I doubt I would know where to look anyway. Any clue what this could be or what I can do to prevent it from happening again? How was it getting the power?

 

EVAP system is open somewhere. Check your EVAP routing. For me, I had to take out the intake manifold and on the underside of the intake manifold, there's a tube which came off the EVAP ventilation valve.

 

This makes sense, for a while before this I had a p2402 CEL for an EVAP leak (on a generic reader), but it randomly went away when I recharged the AC. It was out of sight out of mind.

Thank you for the specifics I'll start rooting around this weekend.

 

On the N18, you can access the evap valve without removing the intake manifold. Maybe it's possible on the N14 as well.

 

I'm hoping this is the case but the n14 doesn't like to make anything easy. Luckily there is a superb write up on the forums on how to get it done for someone at my skill level.

 

On the N14 it's possible to remove the tube without undoing the intake manifold, but you will need to have very small and very strong hand to get it done. Also, you will need to navigate your fingers without being able to see what you're pulling. Might as well remove the manifold, it's not that hard. While the manifold is out, check your intake valves, too. If it's got carbon build-up on the valves, you'll want to either clean it on your own to the best of your abilities, or get some way to walnut blast it. By the way, that noise from your video comes from the HPFP's cam drive mechanism. So I'm pretty sure one of those tubes in the EVAP ventilation has come loose.

 

I think I'm going to pull it for experience sake. The biggest issue is once I see those cylinders it's going to be hard to ignore what I know is going to 85k miles of carbon build up, so I may as well start looking for a walnut blaster in the area. I knew it was going to need to be done when I bought it, but I got that mental timeline of when I'm going to get things done vs. learning to do them myself... the car has its own timeline.

I really appreciate the help from everyone.

 

Weirdly enough, this happened again last night with almost identical circumstances so I attempted this today. I wasn't successful but I did learn a lot and got a bit of confidence.

Followed a crazy detailed write up (13 page PDF with pictures) by a member on cleaning your own cylinders. Since I just wanted to remove the intake manifold I only needed half the guide. However, when I got to the actual removal of the manifold, I failed. I removed all the proper hoses/sensors airbox, noisemaker, then the 5 bolts. The manifold was definitely loose but still unmovable. It really feels like there is another something securing it from the underside that the guide failed to mention. Since it's my daily driver I put it all back together with the intention of giving it another go in a few days.

There was something that came out of it. My idle is way smoother. It used to idle 720 to 880. Now it idles at 790 to 815, not sure why it changed.

 

Some MINIs (the R60, for example) have a "hidden" bolt for the intake manifold that attaches to a bracket beneath. I don't know if an 07 MCS has that but worth checking out.