2nd Gen R56 Cooper S Loud Multiple High Intensity Pre-Ignition knocks?!

Lately when driving my 2007 MCS and it's not fully warmed up I sometimes notice LOUD multiple pre-ignition knocks when I step on the throttle say 75%, I'll say about three of them! It's like high intensity lightening in a bottle, when you hear it, it scares the crap out of you!

Now I know I should wait until it's fully warmed up to be going anywhere near WOT, but none the less it's something I have noticed and perhaps it could bite me later, a sign of things to come. These high pitched sounds get your attention if you're near the car when it happens.

I have had all the timing chain components replaced by my Mini Dealer ($1627), dealer mechanic explained when asked, that he adjusted the timing mechanically on the cams, then checked it when plugged into the computer for programming the timing via the ECU.

My only guess with my limited knowledge is carbon build-up on the intake valves, I recently had my valve cover replaced (also PCV since it's integrated) and no longer need to add any oil between 5000 mile oil changes when before I needed a quart every 800 miles.

Your help is appreciated!

Regards,
Systemlord.

 

I knew I would have needed a carbon cleaning eventually, just didn't think it would be at 49,000 miles. What happens if the dealer walnut blasts when there is carbon on the valve seal or does this kind of thing happen a lot? I could see excess carbon on the back side causing issues with the valve closing fully. Is this what that is, the carbon on the back side of the valve?

Thanks,
Systemlord.

 

I have found out that the pre-ingition only happens when engine is only warm in "Sport Mode", optimal engine temperature is not yet reached. I think it's definitely carbon causing the problem, is there any way I can get this covered under my 6-year warranty?

I Live in Mission Viejo Southern California.

I have always used Shell V-Power 91 octane

 

Does the 2007 MCS even have a knock sensor?

 

Can this explain the sound I'm hearing? One way or the other it's time to get the walnut blasting done now!

 

I'm having the walnut blasting done on Monday morning by Irvine Mini in SoCal, don't know what performance improvement to expect...? I have 49,664 on the odometer and she drinks about a half of a quart of oil every 1500 miles since I bought her in March. Runs like a champ which is why I bought it!

 

Periodic backfire inside intake manifold!

Here's an update, I had the intake valves walnut blasted on Monday at the Irvine Mini dealer and boy was it bad! Even after replacing all of the timing chain components, new valve cover and a carbon cleaning of the intake valves I still have periodic pre-ignition. It doesn't happen very often only on occasion, in hot or cold weather. The only time I don't hear them is WOT when driving my Mini hard.

Yes I'm using 91 octane gas from Shell, Shell V-Power .

Thanks for all your help!

Thank you, Systemlord.

 

It's been awhile since I updated this thread, I found out why I'm getting pre-ignition. I ran a couple of bottles of BG 44K Fuel System Cleaner, the area in the center of the pistons directly under the spark plugs is spotless! When I ran one of those 5mm diameter cameras down into the cylinders I can see carbon around the outer edge of the piston, I'm going to have a BG service center perform a 3 stage cleaning method similar to a meth injection system on my MCS. I'm looking at getting a meth injection system probably this Summer.

Systemlord

 

You ever wonder why CA does have or allow 93 octane?