Assignment

A (horror) vision for the future: Chip tuning is not unlike the more fashionable manipulation of the digital speedometer. One meets up with somebody at a motorway restaurant who, e.g., for a certain sum of money, connects a laptop to the Controller Area Network Bus and changes the engine characteristics map of the engine control module. When one again goes out on the highway, it's clear that there is distinctly higher torque and better performance than before.

Function

That's what one imagines, and technically this is, with the right access authorisation, certainly quite feasible. It isn't however, quite as simple as one thinks. First of all, one should ask oneself how the data was obtained. There are teams of engineers who sit (or stand) for very long periods at test benches and test various settings. By the way, this work is no longer done exclusively in the motor-car factories any more. There are the software suppliers who are also bound by absolute top-secrecy, e.g., in the case of newly developed engines.

The aim of all these actions is to determine the influence of all the injection amounts and the injection point, (diesel) or the ignition point (petrol). Where, in each case, the most favourable characteristic curve is determined, e.g., at a certain coolant temperature, accelerator pedal position, load-demand, exhaust gas composition etc. In this case 'favourable' means for the performance, the consumption, the exhaust gas emissions, the noise development, the engine service life, and a lot of other things as well, also the adherence to certain legal requirements. In this case, every additional parameter, (e.g., influence of the automatic transmission) means not only a doubling, but a multiplication according to the number of the supporting points.

Here an example (practical and very simplistic): If only one value each is given for every 2nd accelerator pedal position change, for the injection amount and for the injection timing, this would mean that for approx. 60 times, already 30 new values. Now, every 50 RPM a new value is determined for the RPMs only up to 4500 (diesel engine!). This makes 90 additional supporting points and a total of 2700 values. Since each accelerator pedal position must be combined with each RPM. If 80 engine temperatures and also any number of varying load signals also come in, the engine characteristics map already has 17.28 million values. Every incoming value must be multiplied by this number. For modern memory chips this is generally not a problem.

Now, these are already 4 dimensions which can no longer be made visible in a diagram. These values are still saved, one after the other, in the memory of a control device. Of course one can select these, alter single values and burn, or read them in again. But what has one actually changed? Was that the injection amount for -20°C and 32° accelerator transducer at 2210 RPMs and 32% load factor?, or maybe not. A processor can handle such amounts of data in the smallest conceivable unit of only a single machine-stroke, that's too much to ask of a human being.

Because of the complexity, many chip tuners turn, at least with the diesel, basically, only two setting screws. One changes the information which the control device receives about the engine temperature through the appropriate series resistors. They feign a lower temperature and cause a slightly richer mixture. This provides relatively little increased performance. However, it is possible that the engine characteristics map is really altered, which relates, among other things, also to the bypass valve which is controlled electronically nowadays by the turbo-charger. Using this method, a distinctly higher performance is obtained, for which, unfortunately the engine was not designed.

What do we learn from this? The in-feed of new data can be tested just as extravagantly as that of the car manufacturers. However, it can also be bungled. And the consequences? It was never so easy to tune-up an engine, but previously, one often had at least one more chance to recognise the botch-up. The consequences are just as hard as before:
- Loss of the general operation permission,
- Loss of the (mobility) guarantee,
- Proof of the tuning measure is possible at any time,
- Risk of defective parts through stress overload.

Finally, one thing still remains to be said. What actually happens here, is that higher performance/torque is coming from an otherwise, absolutely unchanged engine, a possibility which the manufacturer himself could have used directly. And why did he not use this possibility? Here is only a small choice of possible reasons:
- The torque would be murderous for the (manual) gearbox.
- Only thus, could certain exhaust gas limits be adhered to.
- The engine would not be able to cope with the higher thermal and/or
  mechanical demands.
- The manufacturer could avoid the cost of certain extra
  strengthening/cooling.
- The maximum speed would have required other (more expensive)
  tyres.
Actually, any one of these 5 reasons should be enough, for anyone to give chip tuning a wide berth.

By the way

We have received a few critical e-mails because of this clear expression of opinion. Unfortunately, in none of these e-mails has anyone produced arguments against the facts mentioned in the text. We know that there are renowned companies for chip tuning, and that these companies sometimes also offer a guarantee. We remain, nevertheless, with our opinion. 12/09