I'm having a very strange intermittent problem. Every once in a while my Mini will make these popping noises that sound almost like a backfire, but they're not coming out of the end of the tailpipe. It sounds like it's coming from somewhere underneath the car.

I can't really tell if it's happening while I'm driving but when I'm parked and idling it's very noticeable. It's not very loud but I can actually feel it when I'm in the car. For example, if I have my arm resting on the center armrest and it makes the popping noise, I can actually feel it through the armrest.

My completely uneducated guess is that it's exhaust related but I have no clue what to look for.

And it doesn't always do it so it's gonna be a ***** to get the dealer to be able to troubleshoot it.

Any idea what this could be? It's a 2011 R57 with 10K miles on it. I first noticed it a few months ago, probably when it had 6K or 7K miles on it.

 

Sport mode on? If so, that popping is normal upon deceleration.

If it is happening at idle with the car stationary there is something else wrong, like a broken motor mount or an exhaust hanger broken. If you have an S the usual suspects like the high pressure fuel pump or timing chain tensioner should checked out.

 

It's not an S. And the only time I hear it is when the car is stopped and idling. And like I mentioned, it's intermittent. I'm taking it in for the yearly maintenance in about 2 months so I'll mention it to them then but I'd love to have at least some idea of what might be causing it otherwise, since it's intermittent, they're not going to be able to replicate the problem and are going to tell me it's fine and it's all in my head.

 

Hmm....throwing darts here: exhaust, motor mounts, bad spark plug, bad coil, failing fuel pump, gas tank pressure (mine thunks a few times when I fill it entirely), plugged fuel filter, plugged catalytic converter, bad fuel injector, bad gas (use Premium TopTier)...The dealer should be able to find the problem.

 

Sounds like a exhaust leak. Start your car and plug the exhaust with a rag and listen for hissing (leaks). The rpm will drop some and its normal. Don't keep it plug for two long. You may need a second set of hands so you can listen up near the engine and under the car.

 

Here's another piece to the puzzle. Every once in a while I hear a faint high pitched whistling noise coming from the undercarriage from the same place I think the backfires are coming from. It's also intermittent.

Does an exhaust leak still sound like the most likely culprit?

 

It could be an exhaust leak. Either way its under warranty since its a 2011, just take in and have the dealer look at it.