I have a 2007 R56 Mini Cooper S and when I start the car often the rpms will waver. To make it more clear the car will rev itself like vroom vroom vroom like its struggling to stay on. Then once I pull out of my parking spot and get on the road, anytime I slow accelerate the car will jolt a couple of times like it cant accelerate then once its above 1500 rpms its fine. Any idea what this may be?

There are no aftermarket items on the car aside from a new muffler.

Let me know if you need any more info or clarification.

The car is in the shop now for this issue but I wanted to ask the general public to see if they knew.

 

Mine does this sometimes when I start it for the first time in the morning. I wouldn't say its struggling to stay on though...just a loopy idle.

So, maybe mine's a different thing all together...

 

A muffler can change the back pressure. At lower RPMS, back pressure is important with some engines. Did it do that at all before the muffler change?

 

I have that, it goes away after first start thinking might be the gas...

 

I thought that at firstbut the smallest pipe on the muffler is bigger than stock. This has been happening for a long time. Enough to verify that it's not the gas. :-(

 

seems like if i use shell it goes away....

 

I have tried just about every company of gas out there and it all seems to be the same.

 

That's what I meant. The new muffler has more flow, reducing back pressure. It's possible the lack of pressure is making the car hesitate.

For example, on my Honda streetbike, there is a valve in the exhaust and one in the air box that changes depending on RPM. The valve in the exhaust controls the amount of back pressure. At lower rpms it creates more pressure to help with throttle response and smoothness.

Might be apples to oranges example but it's something to consider if didn't hesitate before the muffler change.

 

I honestly cannot remember if it did or not before the muffler change. I just got off the phone with mini they are replacing my fuel injectors cause it's misfiring in the 3rd cylinder. I am also bringing my car to a mienake to get the stock muffler back on.

 

it happens to my car all i have is a coustom intake but it did it before that was installed

 

Might be the deceleration fuel cut off. Does this happen in 1st most of the time? Try rolling slowly in a higher gear if so. It happens to me sometimes. Darn electronic gas pedals these days :\

 

A misfire could certainly cause the concern you're describing. I'm thinking you should save yourself some money and leave the current exhaust on the vehicle. A larger muffler/piping will net you some mid-upper end HP and potentially lose you some low-end torque, but I've yet to see an aftermarket exhaust cause that kind of symptom.

Look into fuel delivery and vacuum leaks. Both can cause misfires, both can cause ridiculous idle and stumbling.

Cheers!

 

I just got the car back. The replaced the ignition coils not the fuel injectors. Still has the problem though..... At this point I am starting to feel as though my dealer has a completely incompetent service department. If the problem isn't fixed, DON'T GIVE ME MY Fing CAR BACK!! I'm bringing it back next week. I swear they better fix this or really I don't even know what I'll do. Is there anyway they can just exchange my whole car .


Happens in 1st and second. Idle is well idling, then first acceleration does it, then sometimes in stop and go traffic and i think its in 2nd at that point.

Thanks for the pointers. I will bring that up to my service department cause they clearly cant figure it out.

 

Just heard of a similar problem on a GTI MKV. The problem was the PCV valve. Anyone know if that could be the problem I don't know enough about cars to know if that could be a problem on the mini or if the mini even has one. Thanks for any responses