BMW/MINI Specialists Based in Essex

Keeping Your Car In Tip Top Condition Is Our Aim

With 15 years' experience and being proud members of the Good Garage Scheme, Hallmark Auto Engineers Ltd are the BMW specialists to come to in the Essex area. Our competitive rates are second to none.

We use latest technology diagnostics including Smoke Pro and are constantly updating our diagnostic-check software.

Providing you with a fault code is not what a Diagnostic check should be. When choosing where to take your car, it is important to consider whether the garage has the ability and knowledge to be able to wholly assess the fault.

Unfortunately, there are a significant number of Independent garages who advertise the fact that they have diagnostic equipment, yet have not invested in the dealer level equipment necessary to give you an exact answer to the fault code. Their equipment is able to provide a fault code but they may not have the ability or knowledge to carry out the appropriate testing to ascertain the exact cause of the fault.

This then leaves you with having to pay again to have the diagnostics done at another garage who does have the equipment / knowledge to be able to give an accurate assessment and then be able to a) give you the cost of having the work undertaken, and b) undertake the work should you decide to go ahead.

We have invested in dealer level software and other test equipment that allows a far superior level of access and unlike other diagnostic tools, it enables programming. We have the capacity to carry out tasks such as key programming, software updates, renewing control units and engine re-mapping; all of which need to be coded to the vehicle. We have concentrated on BMW and Mini. Part of our investment also includes specific training for technicians which is run by Master Technicians and specialist Software Engineers.

We are of the opinion that having this equipment enhances the capabilities of our already experienced technicians and ensures that we have the confidence as an independent garage, to undertake any service and repair work required and enables us to specialise without having to involve the dealer.

Coming soon....

Walnut Shell Blasting - Engine Cleaning Technique

Walnut Shell Blasting Benefits:

  • Cleans Valves
  • Cleans Intake Port
  • Removes Build Up
  • Reduces Hesitation
  • Improves Air Flow
  • Improves Acceleration
  • Restores lost Power

The engine inlet chamber and inlet valves are cleaned from carbon build up that is a common problem on modern direct injection engines. The De-Coke procedure is carried out via walnut shells being blasted into the chamber.


Walnut shell blasting is a safe way to clean the lining of the intake because walnut shells, when broken down into fine granules and blasted at high speeds, effectively remove deposits and maintain the integrity of the intake's lining. The high speed blasting doesn't create unwanted grooves in the intake even though shell granules make contact with a backed pressure of around 90 psi.

Unlike sand and other abrasives, walnut shell granules don't wear metal they only remove loose deposits that aren't part of the intake's original design. In essence, walnut shell blasting only removes what is necessary, which is why it has become the most viable solution for cleaning intakes.

Why Does Carbon Build-Up Occur?

Carbon build-up occurs in turbo applications or high-performance applications where excessive blow-by of Air, Oil and Fuel vapour occurs. This creates a positive pressure in the crankcase. Engine manufactures have placed a valve on the engine block which releases this pressure. This valve is known as a PCV (Positive Crankcase Ventilation) valve. During engine operation, blow-by gases, as well as oil mist from the rotating components of the engine, pass through the PCV valve and are routed back into the intake for the engine to burn off. However, some of the oil mist and other products settle along the engine intake and over time form a "gunk." This is much more common in modern direct injection engines as the fuel does not clean the intake valves anymore unlike older engines. The fuel is fed straight into the combustion chamber creating a better burn and efficiency. The downside of direct injection is excessive carbon build up on the intake chamber.

What are swirl flaps?

Swirl flaps are designed to create swirl or tumble of the air to aid better combustion under light load where soot levels tend to be dominant because of the lack of air, they are also there to help with driveability in low load conditions, they are controlled by a vacuum or solenoid actuator and are closed during light-load operations such as when idling at traffic lights, changing gear and deceleration to maximise combustion efficiency, fuel economy and emissions performance. The flaps are fully open during higher load conditions to maximise volumetric efficiency and power output.

The swirl flaps are a poor design, they are prone to failure. When the swirl flap breaks, the debris falls into the engine, either sticking in the valve port and jamming it open, causing the piston to collide with the valve, or falls into the cylinder itself causing the piston and head to become damaged.

What is the solution?

BMW introduced an updated manifold in 2004 to address this problem, the spindle of the valve is thicker and stronger, this design is also prone to failure, another option is to purchase a new manifold and install it, however, you will still have the potential for the same problem to occur.

The easiest and cheapest solution is to use custom manufactured blanking plates, the blanks will fit in place of the current mechanism; there is no modification required! The plates are manufactured to the highest possible standards from aluminium.

The car will function the same without the flaps, the flaps are there for emissions purposes, however the car will remain within guidelines and you will not notice a performance change!

Call in or call us for free on the number above to discuss how our diagnostic equipment can get your BMW running perfectly.

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