General Introduction

From the inception of the first internal combustion engine, there has been the need for control over the behavior of the engine, or ‘tune-ability’. One cannot simply pour an unspecified amount of fuel into an engine, nor fire a spark in the cylinder at random and expect to achieve a satisfactory result. Such variables need specific control to be effective, allowing not only the correct amount but timing of delivery of these variables.

A good example of this is the first motorized carriages ever produced. These early examples of automotive engineering simply had one lever to control fuel and another to advance or retard the timing. As the engine changed in respect to load or RPM you had to ‘play’ with the levers until the engine ran its best. This gave way to the carburetor and distributor system, which automated the task of calculating the correct fuel and ignition timing delivery for a given load and RPM.

Introducing the ECU

A further evolution was the Electronic Control Unit (ECU). Inputs to the ecu including Mass Airflow (load), knock senor technology, engine and air temperature sensors allowed engine tuners to precisely calculate fuelling and timing for any given load and RPM. With the correct sensors providing feedback, the ECU was also able to control such things as boost, cold starting, and altitude correction for fuelling and mixture control (lambda). Another important part of the ECU’s function is to monitor and log fault conditions within the engine management system as a whole. The diagnostic capabilities of the ECU are combined with the vehicles anti-theft system to ensure that the system as a whole is secure and nothing undesirable can happen.

Introducing the Chip

So how does a chip actually work? The tuning information inside a chip for fuelling and timing is commonly referred to as a 3d ‘map’. This map functions exactly like a common spreadsheet, with rows and columns. One axis, say columns for example, is assigned to be load, and the rows to be rpm. Thus as the engine rises in rpm the ‘lookup’ point on the table would slide from left to right along the row, and if the load were to be increased you would see the table from top to bottom. Scaling or resolution of these tables is normally very accurate, with mass airflow calculated in grams per second and rpm incrementing by 250rpm per row. This allows fine control over the fuelling and timing requirements of the engine, regardless of its operating conditions. Each map has a particular function, for example cold start fuel enrichment, air temperature correction and of course main fuel and ignition timing are just some of the three thousand plus maps that are used in a modern ECU.

Development

When initial development is done on a vehicle, the ECU’s memory is read out using specialized software. This ‘dump’ of the memory is then analyzed by professionals to identify the key areas relating to tuning information for the engine. Each map is then given load and rpm scaling, along with values that relate to the real world i.e. injector pulse width and degrees of ignition advance. Once the extensive ground work is completed it is a matter of developing a new tuning file for the vehicle using a device called an emulator. This ingenious device allows our software engineers to see the information that the ECU is requesting from the memory chip in real time, and make changes to the data on the fly. After many, many hours of manipulation, the code is changed to reflect the best power and torque settings without compromising durability.

So does this mean that the manufacturer has made mistakes or has not done their research correctly? In most cases no. The producer of a given vehicle has to allow for a wide range of tolerances and differing driving styles. Some people expect to drive an engine for 300,000 + kilometers and never change the oil. Some people simply are not enthusiast drivers, and will never spend the extra on a better quality fuel, and are not interested in the sharper throttle response and improved acceleration that such fuel and tuning will deliver. When a vehicle is produced it must be able to operate the world over, from the coldest winters to the hottest desert summers, from the lowest point of sea level to the highest mountain conditions. With all this to keep in mind, the standard tuning is normally very conservative. There are also situations that arise where by a manufacturer has a ‘power hierarchy’ of vehicles all with the same engine configuration. This usually occurs as newer models with cosmetic differences are released, with the earlier models having a detuned version of the ECU to allow end users an upgrade path in the years to come. For the sports driving enthusiast, spending a few more cents on a decent grade of fuel and performing a regular service is not a problem, meaning that there is no reason not to enjoy the performance of the top of the line model in your class, or even the power of the next year’s model - today.

How the Results are Achieved

With the power to alter the tuning of a modern engine with such superior control, tuning for individual requirements is not a problem. All Powerchip enhanced programs need to be individually matched to each car. This process ensures that variant coding such as tuning information, transmission type, traction control, malfunction and limp home modes, VIN numbering, and anti theft systems are all kept together as a package. This guarantees that the vehicle can be diagnosed and serviced. Sports exhaust, hi flow air filter modifications and even varying fuel grades in regard to octane level can all be accounted for. As a part of the development process power and torque is maximized for all grades of fuel, standard (91), premium (95) and 98 octane RON. Quite often a completely different set of new tuning data is formulated to suit the differing grades of fuels, ensuring that even if you cannot get access to the higher octane fuels you can be assured of more performance with a program that has been developed for your particular requirements. A hypothetical example of different ignition advance requirements (based on a BMW 325) is presented below.

The best gains in both power and torque will always be with the highest octane fuel, as the superior composition and manufacture of such fuels mean they burn with a ‘bigger and brighter’ bang than the lesser grades. Almost directly related to the octane rating of the fuel is the determination of how much ignition advance, or how early, the fuel can be ignited on the power stroke. With the lesser grades of fuel trying to start the burn too early results in multiple flame fronts occurring in the combustion chamber, the fabled onset of detonation or pinging. As the fuel quality rises so does the ability to burn ‘cleanly’ across the combustion chamber, avoiding detonation. What all this means is that essentially the earlier you can start the combustion process the more of the given fuel charge can be burnt effectively, directly leading to a superior combustion efficiency and power output.

Further reading:

• Is Powerchip smarter than the manufacturers?
  
• Powerchip's 7 steps development process