What is TDCI engine?


TDCI means Turbo Diesel Common rail Injection. Instead of having a distributor pump with a divide pipe to each injector, the common rail is just that. A single pipe (or rail) connected to each four injectors. The fuel is allowed through only when the ECU triggers the injector. These common rail systems run at very high pressures (in excess of 25,000psi) so please do not attempt to dismantle one unless you have the related experience. You may very well badly injure or kill yourself!

What is TDCI and TDI remap?
As a manufacturer develops a new car they have to take into consideration all of the conditions it might be subjected to in all of the regions in which they aim to sell this model. This means instead of just optimising the ECU’s program or ‘map’ to deliver the best performance or the mainly fuel efficiency they have to make compromises to the map to take into account these potential differing operating conditions. These could include sub-standard fuels, extremes in temperature and altitude, differing emission laws and even the possibility that vehicle may not be serviced on a regular basis and in accordance with the manufacturers recommended instructions.


Electronic control unit remapping is taking a read from the ECU’s processing chip of the vehicles standard compromised map and adjusting different parameters within the map such as fuel pressure, boost pressure (on turbocharged applications) ignition advance and throttle pedal control amongst others to free the true performance from the engine. It is a totally safe process as it is just giving the engine the performance it should have had in the first place before all the compromises were applied to the unique programming. Every engine will have its own unique map and by adjusting this we can fine tune the characteristics of the engine; unleashing more power and in many cases reduce fuel consumption too.

Benefits of TDCI remap


After TDCI remap to your turbocharged engine, you will enjoy:

    • High injection pressures independent of the engine speed.
    • Good fuel atomization also at the beginning and the end of each injection due to a constant rail pressure.
    • Edible and correct choice of injection begin and injection duration due to electronic control.
    • Possibility of a pilot injection to reduce noise, particulates and NOx emissions.
    • Reduced need for swirl intensity at low engine speed due to high turbulence energy of the spray.
    • Reduction of noise and material stress due to a silent high pressure pump with low torque oscillations and low torque peaks.
    • Increased horsepower.
    • Increased torque.
    • Better throttle response.
    • Smoother power delivery.
    • Improved fuel economy.
    • Safer overtaking.

Saving fuel with TDCI and TDI remap


As soon as we remap a vehicle, particularly when fuel saving is the priority we focus on improving the low end torque in particular and widening the power-band as far as we can.

This raise in low end torque will mean less throttle pedal input is required to maintain cruising speeds, when fully laden or when on a gradient. It will also mean that the vehicle will be more comfy in higher gears at slower speeds as well requiring fewer gear changes overall.

If you merge these factors with adjusting your driving style to make the most of the additional low end torque you will see an improvement in fuel consumption. This is most effective on turbo-diesel engines where the savings could be as much as 20%!

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