When one purchases a vehicle they likely expect engine ECUs to be optimally mapped prior to sale. While they are normally very well mapped, whether or not it is done in an optimum way is very subjective.
In this article I will look at engine/ECU remapping and chipping and the use of tuning boxes. Particularly, I will explain why remapping works and in most cases, why it is safe.
With most manufacturing, compromises have to be made. ECU maps are no different. Yes, manufacturers invest a great deal of time in engine tuning and testing in the harshest climates. However, tuning criteria is designed around extremes that do not necessarily fit the requirements of the average customer or where the vehicle will be used.
Manufacturers have to adhere and comply with various legislative constraints surrounding emissions and other parameters that are set by the various governing bodies. As a result, this may affect the quality of factory ECU maps, with regards to available performance and/or MPG.
Many manufacturers produce vehicles in their range that to some degree compete with each other and in some cases even share the same engine. For example, a VW Golf may share the same engine as a VW Polo or a Porsche Boxter competing with the Porsche 997. The point being that it would be marketing suicide for a Porsche 997 to be considered slower than its younger brother. As a result, some engines are intentionally detuned or let’s say, not tuned to their full potential.
Furthermore, manufacturers are obliged to tune vehicles for wildly varying conditions, i.e. -40 to +130 degrees or really high altitudes where the air is much thinner. This is one of the reasons why engines run rich from the factory. It’s to accommodate dramatic climatic conditions that the average driver will never see. Even with the latest technology in fuel and ignition control, compromises on engine tune still have to be made just in case the vehicle is used in such conditions.
Vehicles need to survive the factory warranty period without fault. For example, it’s not uncommon to find an engine that is detuned with regards to torque output to ensure that the drivetrain doesn’t fail. Now, this begs the question: Why would anyone want to remap/chip their vehicle if there is an increased risk of component failure?
Well, here is the point I am really trying to make here. Car manufacturers must tune vehicles to cater to customers that are mechanically unsympathetic! This is very important. Drivetrains or engines (as an example) can fail when they are abused or raced from cold. It is this type of customer and not your average enthusiast that manufacturers are really trying to protect themselves against, at least within the factory warranty period.
Furthermore, fuel quality is not guaranteed. Customers embracing remaps are more inclined to use higher-quality branded fuels and/or fuel conditioners, unlike the average user. Manufacturers have little control over this so engines are tuned accordingly and with a little to spare in regards to turbo pressure, air/fuel ratio, ignition timing, etc.
A combination of the above is why we see so many forced induction engines running rich from the factory. This and all of the above gives reputable tuners the opportunity to liberate additional performance in a safe manner and under certain conditions, improve MPG from engines.
If in doubt, stick with reputable tuners and tuning box manufactures as this helps ensure you are receiving a well-developed tune.
Also bear in mind that even though normally aspirated engines can be remapped, the gains are very small when compared to forced induction engines. It would also be prudent to notify your car insurance provider.
UPDATE: We were asked how ECU remaps or Tuning Boxes can improve MPG?
With naturally aspirated petrol engines mpg gains are marginal at best. Minor adjustments can be made to ignition timing and air/fuel ratios but both power and mpg gains are minimal. This is the case with virtually all non-forced induction engine.
With turbo or supercharged petrol engines power gains usually very good with tangible but small MPG gains. MPG gains are two-fold on forced induction petrol engines. Many turbo charged engines run very rich from the factory under acceleration (open loop lambda). By carefully leaning out air/fuel mixture under open loop conditions fuel consumption can be reduced. This is more difficult with more modern engines that utilise wideband lambda technology. That said, most of the gains (if any) are achieved by improving the spread of torque across the rev range, or in particular, lowering it. If more torque is available lower in the rev range then less throttle is required to achieve the same level of accelerative effort. Of course, more fuel may be required to achieve the additional torque but lowering engine RPM more than compensates for this. And this is where diesel engines excel…
Turbo diesel engines – very good power (torque) gains and potential mpg gains. Most mpg gains are achieved in turbo diesel engines by using the principle described above – making more torque available lower in the rev range. If you used to use 40% throttle but now only have to use 35% throttle to achieve the same accelerative effort then you will most likely save fuel, once the novelty of the extra power has worn off!
Hope that helps.