My MINI is an out of warranty 03 Cooper automatic. I have been hearing a hissing noise coming from the pedal area, and it has been diagnosed as the brake booster. (This was just from a local guy listening to it, though, not actually running any tests.) The hissing has progressively gotten louder. It only quiets when I press the break. When I release it, it becomes very loud. (This seems opposite what everyone else says the brake booster symptoms are.)

I've also been noticing lately and issue with my MINI sputtering when idling. It is idling @ about 1100rpms for about 5 seconds, then drops to about 800 and seems to bounce a bit. It almost shudders ocassionally. Today, it died on me while sitting at a stop light. I put it in park, turned the key off, back on, and we were good to go.

It did this to me a couple weeks ago also, but I had just pulled into a parking spot, and I think it was already in park, just not shut off yet, and it died on its own.

Could the hissing be related to the sputtering and dying?

We already bought the Brake booster, but haven't replaced it yet.

The three MINI dealerships that are remotely (2 hours away) close to us have never had a MINI with a brake booster go bad, according to them.

 

It very well may be the brake booster. If you are loosing vacuum through the booster, that might be a cause of the idling problems.

 

Thanks. That's good to know. I was getting worried that I would have multiple expensive problems on my hands.

 

Update: Brake Booster has been replaced, now. I could swear I still hear a very very slight hissing, but it could be my imagination. Hubby is checking when he gets in tonight.

I am now idling at around 800rpms, which seems low, but I'm no expert.

I am concerned, though, because my oil light just started lighting up and after checking, I am probably about a quart low. I just had my oil changed about a month ago.

 

The idle is about right.

The low oil is not. Be sure and check the pan plug and the oil canister for leaks, if not there then oil pan. How many miles do you have?

 

She's got about 66K miles on her.

After looking, I did actually change the oil about 2 months ago. (Time flies, right?)

The shuddering is still there, but I'm starting to think when I turn the air off, it isn't there. It is sporadic, though, so it's hard to tell for sure. Maybe my car is trying to tell me to be more eco friendly and not sit at a drive thru with it running. : )