About 2 years ago, my 2011 All4 (manual) was having the stumbling/hesitation issue under acceleration. But I eventually got it fixed with update SI MI2 02 11.

Well, 18 months later it's back but a little different and a lot worse. Now it happens under a lot of conditions (uphill, downhill, steady throttle or acceleration), but always around 30-35 mph. The stumble is sometimes so abrupt, it throws me into the seatbelt like I slammed the brakes or the engine is about to stall. But a split second later it's all normal again.

The first time was in mid-February, 4 times over a weekend. I took it into the dealer but there weren't any codes or CEL. They couldn't reproduce it and gave it back. Three weeks later it happened 3 more times over 2 days. So I took it in again, and they still couldn't reproduce it. But this time, before I took it back I rode with the tech and got it to happen with him in the car.

That was 9 days ago, and they can't figure out what's wrong ... plugs are good, fuel pressure is good, turbo checks out, no codes or CEL. They updated the ECU just in case, but it still happened after the update. Seems like it's a lot more frequent now.

So now they're out of ideas and want to escalate the issue to Mini.

Any thoughts on what might be wrong?

 

could it be clogged valves carbon build up? have they pulled the covers to check? you might need a carbon blast .

 

Because it happens so fast, and then is normal again, makes it seem electronic in nature, and not a fuel or valve breathing issue like carbon build-up. Coil issue or maybe throttle motor issue that doesn't set any faults.
If it was my car, I'd swap all 4 coils out with 4 know good ones and drive it to see where I was at.

 

Well the only reason I mention it is because I had a similar experience...after taking it to the dealership they did many things under warranty and some not, but...one of them was change out intake to the new improved cold climate intake...because it has been below normal temps here and another was blast intake valves with walnut shell and low and behold the car had extremely more power and getup than it did previously and because I had just purchased the vehicle(2nd owner) I had no idea how it was supposed to feel. I had never driven one, the issue that lead to all of this ...Got in my car just to move it from the driveway so I could shovel the endless snow we had been getting...and the car had the yellow engine light in the rpm window and it was stuttering and trying to keep an idle but then it would rise and fall and so I kept my foot on the gas to stabilize it so it could get warm ..not alot ..then I shut it off after about a few minutes. started it back up and it was fine no symbol. I drove it a few times after that no issues then one morning I get in and the engine symbol is now on in the speedo and that is when I brought it to the dealer mind you it was fine driving. They did what they did and updated software and also threw some stuff in to clean the injectors. Long story short the car drives like new and I only relate this because it could be a combo like mine of carbon and intake ice up...I'm assuming of course I could be completely off. Good luck getting it straightened out.

 

I'd wait until MINI responds and see if their suggestion works first. If it doesn't, then its time to make a few suggestions of your own.

 

Thanks for all the ideas. I talked to my service advisor last night and they said after a few more test runs the problem is getting easier to reproduce and more severe when it happens.

The Mini hotline recommended replacing the coolant temp sensor and knock sensor. The parts should be here on Monday.

I wonder if carbon buildup is a contributing factor. I'm at 35,000 miles now. I'll suggest walnut blasting if the new sensors don't fix the issue.

 

Forgot to mention, but I also asked about the plugs and coils, and they said the plugs weren't fouled and the coils tested good. I'll suggest swapping the coils with good ones if the new parts don't work out.

 

My 2015 has/had the exact same thing...started at 1500 miles...now at 3500 and its gone away...

 

Update from the SA ... the new knock and coolant temp sensors didn't fix the issue. The tech is back on the hotline with mini looking for things to try.

I asked about coils, plugs and injectors and they said those all tested good. Doesn't think carbon buildup is a factor because the problem is very specific at about 33 mph when it happens.

They can't believe there still aren't any codes. He implied there were codes on my last call, but whatever.

Wonder what they'll try next.

 

This sounds EXACTLY how my car has been acting! Even down to it happening when the speed is around 30-35mph. I also noticed it happens around 30-45 degrees outside. Very weird yes. No fault codes for me either. One thing I did notice...it seems to happen when I use BP gas. What kind of gas do you use?

PLEASE PLEASE keep me/us updated on anything you find out. The car drives great other than this little weird hiccup. Thank you in advance.

 

Happens every now and then to me too. Have been using Shell Vpower exclusively for the last 4 months based on reviews for fuel quality.

 

Got the same thing after replacing spark plugs with Denso iridium. Put the old plugs back in and hesitation gone.

 

Okay, I have some updates. I guess the problem is getting worse because it happens every time they take it out now.

The new parts list is getting longer. Mini told them to replace the high pressure fuel pump, which didn't help, and then the coils, which also didn't help.

Then they told them to drop the transfer case and check all the wiring. They found part of the wiring harness for the traction control or stability control (SA wasn't sure which) that had rubbed through its insulation. They repaired it and installed a plastic shield so it wouldn't rub metal anymore. If they get 3 good drives without reproducing the issue, they're going to give it back to me and I'll keep an eye on it.

 

Flav, mine happened in all kinds of weather, starting in February between 30 and 50 degrees, and now up to 70+ degrees, so my issue isn't weather related.

Pbkirby, interesting about the iridium plugs. I was going to try iridiums, but my car is still bone stock.

Mini tried to blame the hesitation on bad fuel at first, but I shut that right down. If it was bad gas or the wrong octane you'd hear pinging and there would be codes for timing, misfire or other issues. And it sure wouldn't just happen at 33 mph.

Anyway, I always fill up with Conoco or Shell 91 octane (highest available in Colorado) and use injector cleaner every 3 months or so. The engine has never pinged or stuttered at any temperature or elevation in 3 years.

 

What worries me is the severity of the stress put on the engine\drivetrain parts when this happens, happened to me today accelerating from a stop light, its so abrupt it feels like the brakes are put on full for a split second. My warranty expires in a month..... *gulp*

 

I took car for some new shoes last week and my independant bmw/mini specialist said its a software thing and to ask mini to update. i find it happens with BP gas, otherwise no issues. no probs in a few days since switching away from bp.

 

So who is paying for all the new parts that doesn't seem to fix the problem? They can't keep throwing parts at your car in hopes of a fix on your dime especially under warranty.

 

Get it into the dealer now!

You need to establish the problem with Mini before warranty runs out. Even if it isn't fixed before the warranty expires, because the problem started in warranty they will be obligated to fix it at their expense.

Since OP's problem appears to have been a wiring problem in the DSC system, this might be your trouble too. It would explain why it feels like the brakes are being applied because they probably are being applied by the DSC computer which thinks there is a stability problem to correct. (The engine shutting down would not throw you forward hard; it would feel like stepping off the throttle.)

Good luck!

 

I'm just building a laundry list of things i want them to check before i get it in :D, its a pain to have to switch out 2x car seats and deal with loaners.... im hoping the software update alone that some people have mentioned will cure it (hasnt fixed it for some either, so we'll see).

 

I disconnected the MAF sensor and let it sit for 30 minutes before reconnecting. I also have not filled up with BP gas. Problem has not returned and engine is running strong.

 

Given the corners BP is said to cut in their oil well operations, I guess I'm not surprised to hear their gasoline is iffy too. :-/

 

I have a 2012 Countryman S All 4. I bought it brand new from the dealers barely 6 months ago (been sitting there for a while) - its now just 5,120 miles.

Two months ago I experienced my first power loss with a loud CLICK-CLICK-CLICK noise while accelerating - after a second power came and it was back to normal. It happened again a month ago and I took it to the dealers to investigate. After a day, they gave me the car and said it was engine knock and I need to start using Octane boost each time I fill up. So I did. It is still happening, now multiple times everyday. I am to take it to the dealers next Monday for them to look at it again.

I suspect it is more than just engine knock. Any thoughts?

 

Change the type and location of where you get your gas. Run a few tanks and see if that helps, please report back

 

I have already done that. Now that I have gone through all the major gas dealers, the dealers say I must use the Octane Boost. I have tried the BMW brand boost and the AMS Oil Octane boost and the problem is now recurring more frequently - almost every time I try to accelerate quickly.

 

Get yourself and obd2 reader that hooks up to your phone, download torqueapp, record a short drive and do what you can to reproduce the stumble. In the torque app, you can record engine parameters, record the throttle position, fuel flow, speed and anything else which will show qhat could be happening.