Why Engine tuning is needed.

When modifying a high performance vehicle to increase power, it is vital for engine safety to optimize the air/fuel mixture, engine timing maps and additional sensor maps to suit the performance gain. When bolting on a forced induction system to a normally aspirated engine power is typically increased by 40% and up. Power increases of around 40% place additional demand on engine systems (fuel pump, fuel injectors etc) which usually fall within capacity toleraces. Power increases between 40-60% usually will require certain fuel components to be upgraded. Above 60% may require engine compression to be lowered.

How most car manufacturers(OEMs) tune their engines.

Most modern sports cars use an Engine Control Unit (ECU). The ECU contains electronic circuitry which is designed to safely and efficiently operate the internal combustion cycle under various conditions (temperatures, loads etc). The OEM designers and software engineers with vast resources at their disposal spend countless hours testing and creating software that specifically manages the air to fuel ratio, engine timing and sensors maps. This software is typically stored on an Integrated Circuit (chip) on the ECU Printed Ciruit Board (PCB).

Current tuning methods used in todays aftermarket

Traditional methods for re-tuning to compensate for power enhancements included the use of black boxes to alter sensor signals to the ECU. The ECU would react by interpreting these signals to change the air fuel mixture accordingly. This is often regarded as crude but functional but is not a pro-active approach. Another method would be to use a Rising Rate Fuel Pressure Regulator to alter the fuel pressure going to the engine based on boost level. This is also an unsophisticated but functional process. In cases where stock fuel injectors have inadequate capacity, some tuners plumb an additional injector into a turbo or supercharger system which operates off a programmed injector driver. This is crude, reliability is questionable, the air and fuel do not mix efficiently and can lead to uneven delivery of fuel into the cylinders. Often, a combination of the forementioned methods would be used in combination.

However modern sports car engines extensively rely on a vast range of sensors for On Board Diagnostics (OBD2) and engine management. Using the forementioned tuning methods can lead to Check Engine Lights or limp mode operation.

Standalone engine management is often used in race / rally cars and involves running an additional or compelte replacement fully programmable ECU. This typically requires custom tuning sessions on a rolling road (chassis dyno) to custom tune 1 vehicle at a time. It is expensive, complex and eliminates the OBD2 system (required by law) but sophisticated method of re-tuning a vehicle.

The ultimate method of re-tuning for the engine to dynamically operate within OEM design principals is to re-program the OEM fuel management software. ECU re-programming (Chip Tuning) is a highly complex technique requiring the knowledge and understanding of the OEM programming. A mere understanding of software algorythms is not sufficient and engine mechanical knowledge must also be used in order to re-map the OEM software. Proprietary data from the OEM programmers (Bosch / Siemens etc) is sometimes required to speed up re-engineering development and only a handful of true chip tuners have this access.

Chip tuning gives the tuner the ability to control individiual components such as fuel injector demand, air flow sensor calibration etc thus enabling the use of larger injectors or air flow sensors and their efficient operation all within the parameters of OBD2. Chip tuning has been prevalent in the Germance aftermarket tuning industry for over a decade and is regarded as the only way to tune a sophisticated high performance vehicle.

Hard chip /socketing

Until recently (last year or so) the ECU software was replaced by swapping a particular chip on the ECU circuit board. This involved physically having to remove the ECU, open it and de-solder the OEM chip. A socket would be fitted and the OEM chip or a new performance chip could be installed. This typically requires the customer to send their ECU to the tuner.

Flash Technology

Recent advances in aftermarket chip tuning have lead to flash programming which means modified software can be serially flashed over (electronically overwritten) the OEM software through the OBD2 diagnostic port. This is fast and simple and the ECU does not need to be touched. This is also the method that OEM dealerships install new software updates into cars.

Chip switching

A more recent development from GIAC is the Flash Loader. This handheld device plugs into the OBD2 port and allows you to switch between optional flash programs in your ECU. eg You may switch to valet mode which has a 4000 rpm limiter setup, or kill mode which prevents your car from being started. Another great advantage of this ability is to switch between different software tuned for different grades of fuel octane- most beneficial if going to the race track.

VF-Engineering creates supercharger systems for vehicles which can be chip tuned and believes that there is no other way you should modify your expensive sports car. VF works exclusively with GIAC USA employing flash programming.