Before I begin a little about my Mini it is a R56 2008, 100,000 miles, well taken care of - oil changes at 3000 miles, location - Northeast US, and no internal mods other than an intake. Every time I drive it from a cold start (after letting it warm up a few minutes) it is drastically down on power (Jeremy would not approve ). The car struggles to go; I would say it is down 40% on power/torque when this occurs. In addition, this exhaust note is different it sounds louder, lower and boggy. After around 5 - 10 minutes of normal driving it disappears completely. I gain 100% of my power back and the exhaust changes back to normal? It's weird because I have no check engine light on from this... I can't find what it is! Has anyone else experienced this? If so what was the problem behind it?

Lots of cars act strange before they're warmed up. My '11 MCS runs pretty poorly on a cold start. It takes about 2 minutes of driving or idling to operate normally. As to the exhaust, you will have a louder note on a cold start because the engine idles at higher RPMs.

Sounds normal. Mine takes several minutes to get over 185, on its way to 225. Power is reduced below 185 by limiting boost. I drive it easier until at least 175° anyway.

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The weird part is it has never done this before. I have even let it warm up for over ten minutes and it still occurs until I drive it around.

It's just strange because the problem seems to be getting worse and nothing like this ever happened before.

Use something like the app Torque to check coolant temps, boost level, Afr. Also try a different gas station (you didn't accidentally get 87 or 89 octane did you?). How many miles since you carbon cleaned the valves?

Just ideas.

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When I bought my 2009 with 23K on it a couple months ago, that's how it behaved (although not quite as bad). Cleaning the valves and running fuel system cleaner in every tank of gas solved the problem.

Get your intake valves looked at to see if your Mini is ready for a walnut blasting, in any case put some BG 44K Fuel System Cleaner in your tank and be prepared to be amazed! It's for professional use so only place to buy it is either eBay or even Amazon for about $20 per can. Here is the link to BG's homepage.

Just note that a fuel additive won't help a sticking throttle body or dirty valves.

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The fuel additive I mentioned is for that black carbon in the combustion chambers, it can get dirty on the face of the valves in the combustion chambers. I just added half a can of BG 44K to my fill-up today, it's good for treating a 20 gallon tank. Has anyone pulled their plugs to see down in the cylinders lately with a flashlight? It's going to look just like you valves did before your walnut blasting.

Thank you for the advice. I have never had my valves cleaned, where did you go to get yours cleaned?

Which fuel system cleaner do you recommend? Is there a Mini specific one?

Hello, what do you recommend then?

thank you!

100,000 miles and haven't cleaned them? Non turbo then? The turbo motors foul up the valves in about 30-40k and need a walnut shell blasting. I had the dealer blast mine at 38k. You might give systemlords cleaner a try to clean out the system.

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I used the aforementioned BG 44K.

I took my car to an indy mechanic for the valve cleaning. They used the official BMW (Mini) walnut blaster to clean the valves and cleaned the intake and throttle body while they were at it.

http://crcindustries.com/auto/intake-valve-cleaner.php

Planing on giving this a shot once I make up a boost tap for it..

It is actually an S. How much do walnut blasting a usually run around at the dealership?

I think in the neighborhood of $600-$800, but it was done when I bought the car.

One of our local members built a blaster for under $100.

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Never had your valves walnut blasted and with 100,000 miles! I'm surprised because 95 percent of N14's start to choke and misfire well before 60k, mine started acting up at 47k. Some early owners were force to walnut blast their valves before or near 30k, how much oil do you find yourself adding every so often? You wouldn't believe how much carbon restricts airflow past the valves. You don't have to pay the dealer to perform the cleaning, but they do flash your ECU with updated firmware. I gain quite a bit of performance after my valve blasting and mine weren't as bad as most others.

It just so happens that I ran into a regional manager for BG Corp when dropping by a BG service center to buy yet another can of BG 44K. On my way out the door he walked up to me and asked what car was I using the BG 44K for, I told him my MCS. He said aren't those DI and I said yes, he took down my information and agreed to meet with me on Tuesday in Fullerton CA, he is going to give me a special product specifically design for DI engines for free. I was shock and confused as I have learned nothing free in this world, he wants to perform a before and after compression test and a leak down test.

He told me what other members have stated on many occasions that I didn't believe and dismissed, that blowby gasses blow past the piston rings in both directions and by doing so leave carbon deposits on the bottom and top end of the rings and ring landing. I'll understand more when we meet and he gives me a 3 stage kit that explains everything, it's design specifically for DI engines. He recommended against the usual conventional treatment that BG offers for non DI engines which includes a air induction service and hooking up a BG product can directly to the fuel rail that the engine runs on for 20 minutes.

I'll know more when he gives me the kit that includes something that's added to your oil right before your oil change to remove sludge and carbon deposits in the ring landing bottom and top just like how the blowby gasses do. My turbo oil feed line should be clean up as well, he said that after running this stuff in the oil and run at idle for 10 minutes I should see streaks of black liquid pour out of the drain plug.

Thanks a lot that was so helpful!

Not enough on what you are driving.
Automatic, Manual, S - non S ?
Banana up the tail pipe ?

It is a manual S. And sadly no banna up tail pipe.

One of the things which changes as engine warms up is the Air/fuel ratio....When you first start the engine more fuel is dumped in.

Carbon buildup would be creating misfire codes I would think, as well as all around poor drivability....warm or cold.