Lohen helping solve and prevent the N14 MINI coking issue
The MINI Coke Problem
The N14 engine found in second generation MINI Cooper S 2007 – 2010 and the JCW to 2007 - 2012 and some Peugeot and Citroën’s suffers from an excessive build of carbon (coke) around the critical engine components such as the valves. This build up of carbon has a number of consequences including;
- Reducing capacity, decreases flow of gases which means a reduced amount of air (oxygen) is entering the cylinder
- Oil deposits are mixed with air
- Causes detonation that can cause further issues with burnt out spark plugs and piston damage.
- Damage to the catalytic converter
Some of the symptoms of coking are:
- Poor idle
- Poor acceleration and drop in performance
- Engine light on
- Emission light on
- Error codes for super knock
The MINI De-Coke Solution
Lohen has found the most cost-effective and efficient way of removing the coke build up is by walnut blasting the inlet side of the cylinder head, removing carbon deposits from the valve and surrounding areas and vacuuming the walnut shell and carbon away using specialist tools. We call this the Lohen De-Coke Service. This allows better flow of gases, improves combustion and consequently release engine performance and restores BHP on your MINI to where it should be. 
Walnut shell is used to remove the coke build up on your Gen 2 MINI because it is a very gentle abrasive and does not damage or mark the engine components making it a safe and effective method of servicing. 
Dyno graph showing the performance benefits of a Lohen De-Coke on a MINI Cooper S 2007 car
How often do I need a de-coke service?
We have found that driving style and the type of mileage covered can alter the degree of coke build up but, as a general rule, performance and running benefits of a de-coke service are noticed after 40K miles.
Prevent Your MINI Coking
To help prolong the periods between de-cokes, Lohen recommends fitting an oil catch can into the engine breather system. This helps “filter” the hot, oil-laden vapours before they are returned to the inlet manifold. This will not completely eliminate the coking problem because it's a characteristic of the Gen 2 engine design, but will slow down the coking process and help to maintain the improved performance level for longer. The Oil Catch Can will need to be emptied and cleaned, but this can be done when your MINI is being serviced and is far more cost effective than a de-coke service.
What Services Do Lohen Offer?
Lohen R56 N14 MINI Simple De-coke Service - £240
The Lohen Simple De-Coke Service removes coke from the inlet side of the cylinder head. The service includes the following:
- Visual Vehicle Health Check
- Walnut Shell De-Coke Service
Book your N14 MINI Simple De-Coke £240 >>
In addition to the jobs completed during the simple de-coke service the Full Service provides a more complete picture of overall engine condition and car performance, the services includes the following:
- Visual Vehicle health Check
- Engine compression test
- Engine Leak down test
- Combustion gas test
- Pre de-coke dyno runs
- Walnut shell de-coke service
- Post de-coke dyno runs