The Truth About Piggybacks

There are tuning boxes and there are boxes! We must make a distinction between the cheap plug-in boxes sold by some sellers on popular auction sites and proper tuning boxes.

The cheap ones are very crude in their operation and merely fool the car into throwing more fuel into the engine. This does appear to give more power but over-fueling is not a great strategy and can lead to many issues with your engine.

At their worst, these tuning boxes are just a resistor that alters the air intake signal to the car’s ECU. ChipWerke has even heard of sellers posting pictures of tuning boxes that appear to have a chip and circuit board inside but when you open it up you’ll just find a cheap resistor and a few wires! Be warned and don’t get caught out.

A proper tuning box should be thought of like a piggyback ECU. It will have a processor on it and this will access the live readings from the car sensors and send out adjustments to signals to control timing, boost, and fueling. Readings from car sensors are effectively intercepted and then control decisions can be made by the piggyback ECU or tuning box. The more powerful the processor is, the smoother the power delivery will be.

Carmakers have to build a very general map considering the wide variations of fuel, road conditions and emissions standards of many countries. It makes economic sense to build a very safe generic state of tune that works across all territories.

This strategy leaves a very wide margin for tuning companies to work in. Most can offer more power and greater fuel economy without any sacrifice of reliability. It makes sense to service a tuned car more frequently but at the end of the day, we all want our cars to work as efficiently as possible.

It will need a map stored which reflects the different states of load and be able to trim and adjust the essential engine parameters to suit the current conditions.

Not all tuning boxes are the same, beware of the “cheap fakes”.

Each map has to be set up on a car-specific basis, even different models that use the same engine will have different maps due to variations in weight, gearing and typical use of the car. Quality tuning box companies develop car-specific maps on the dyno or live on the car before applying these to tuning boxes. A good quality tuning box can outperform a cheap generic remap.

We should note that custom remaps do have a place and if you are serious about performance then a custom map is the route you should take. Where other modifications have been added to a car you really need a specific map tailored to your car.

The advantage of tuning boxes is that they can be installed in minutes and updated through the post minimizing downtime. Your vehicle will not be out of action while you take it to a remapping company and you can easily remove the tuning box for servicing or repairs. (A few tuning boxes require a car’s wires to be cut in order to fit it but most will just plug into the existing wiring.)

By tightly controlling the boost, fueling and timing, you can actually make the engine a lot more efficient and smooth out the power delivery. Turbo diesel in particular usually produce better MPG after a tuning box has been installed and make much higher power gains than petrol counterparts.

Good tuning boxes allow a degree of user control over the map used. With the use of microswitches or dials, drivers can select a handful of different setups. This is ideal as you can effectively have one setting for your daily commute and use a more aggressive one at the weekends.

Even within a tuning box, you have the option to control the state of tune. Perhaps you need more low-down torque for towing, want the maximum power for a track day or need a good compromise between fuel economy and power for daily use.

You’ll also find that some cars run better on different maps due to differences in manufacturing tolerances and wear and tear on the vehicle. There is also a need to match the driver’s style and personal preferences; again drivers all have different priorities in what they expect from the car.

So how can you tell if you are buying a quality tuning box or one of the fakes around?

  • When you are buying a tuning box, Chipwerke encourages you to check the reputation of your supplier carefully.
  • Internet and forum reviews can prove helpful. Be aware that many people regard all tuning boxes as the same thing; when in reality there are some that work well and others that are just a complete ripoff.
  • Ask yourself: are they just resellers or do they make, set up and test the boxes themselves?
  • Do the boxes they sell have a good reputation? Is there a money-back guarantee?
  • Are there any rolling road printouts to back up the power gains claimed?
  • Is the tuning box designed specifically for the make and model of your car or is it just a generic one-size-fits-all model?

Cheap boxes are often a dead giveaway. You will get what you pay for. Read reviews and check the forums for other members who have experience with your chosen tuning box supplier. Always buy from a trusted retailer with identifiable premises and a long trading reputation.