Diesel cars have come a long way in a very short time. Not that many years ago “performance” diesel cars were simply unheard of. With the introduction of smarter fuelling, injection and turbo-charging systems it’s not uncommon to see modern diesel cars knocking on 250BHP from the factory.

Not everyone can afford one of Germany’s finest 3.0 twin turbo 155MPH diesel power plants, leaving many power hungry motorists opting for diesel remapping and tuning boxes to help unlock those extra horses and torques.

Gains of up to 50% from a simple remap or tuning box are common place, so lets learn a little more about them.

Diesel Remapping


Diesel remaping is the process of changing the programming on your cars engine control unit (ECU). The ECU is the brain of a modern car and controls such things as ignition timing, air/fuel mixture and (on turbo cars) boost pressure.

On modern cars remapping is performed by plugging a flashing device / laptop into the vehicles diagnostic port (OBD2). The old “map” is saved and a replacement map is flashed / uploaded into the cars brain. The new map alters how much fuel, air and turbo pressure is fed into the engine. Increasing these variables (within safe limits} means more power without the need for any further modifications, however upgrades such as free flowing exhaust systems and larger inter-coolers can compliment a remapped car.

This process can be reversed however it is possible for dealerships to tell that the vehicle’s brain has been “played with”. This is often referred to as the TD1 flag (VAG vehicles).

This can lead to issues in the event of a warranty claim. Remapping should be declared to your insurance company.


Diesel Tuning Boxes


Diesel tuning boxes work by intercepting the signal between the ECU and the fuel injection system. The device alters this signal and allows it to inject more fuel into the cylinders thus producing more torque and power.

One of the biggest advantages of a tuning box over a remap is that these can be fitted at home without any mechanical prowess and removed very quickly. They do not alter the vehicles ECU in any way and are often promoted as “untraceable” and therefore warranty “safe”. These type of boxes essentially piggyback the existing sensors, fooling them into increasing fuel and boost pressure. These are not to be confused with the “resistor in a box” solutions from eBay.

Like remapping, a tuning box should be declared to your insurance company.

What does this mean for your diesel particulate filter DPF?

Concerns over DPF longevity are rightly voiced among those who have experienced first hand the side effect of all this “unlockable” power to be had from remaps and tuning boxes. The extra power is gained my these methods are a result of extra fuel and turbo pressure being fed into your engine. A side effect of this is that your engine will run richer, creating more far more soot and diesel particulate (PM) which will could clog the DPF at a much faster rate. This will very likely result in more DPF regens and reduced life of the filter.

What about other components?

It’s not just your diesel particulate filter that’ll take a hammering. Extra horse power and torque has an uncanny power of highlighting other components that are either worn or unable to cope with all the extra stress. Clutches, flywheels, gearboxes and differentials may require replacing or upgrading to cope with the extra grunt.

EGR & DPF removal

We’re increasingly seeing remapping services combined with EGR deletes and DPF removal. We strongly advise against this. Alerting the emissions controls in any vehicle is an offence. You’ll fail the MOT and invalidate your insurance.

More about DPF and EGR removals in the articles below

Our Advice

Our advise before you opt for a diesel remap or tuning box is to do your home work. Speak to a specialist and use a reputable company / supplier with expert knowledge on your vehicle. We would suggest trawling the owners club forums and read owners experiences.

We need your help!

Has your car been remapped or had a tuning box fitted? Have you had issues with your DPF? We want to hear from you! Please leave a comment in the box below.