The Engine Control Unit (ECU)

The ECU is responsible for the entire engine management. It measures, checks, and controls all important functions of the engine dependent on the current load condition and environmental parameters, such as ambient temperature, engine coolant, oil temperature, intake air density and air flow.

This vital information is gathered by sensors that accurately pick up pressure, temperature, rpm, speed, and air mass (density) signals. This information is then processed by the ECU in conjunction with ignition timing, injection, boost pressure (where applicable), and Lambda patterns, that are programmed as a set of commands to a chip (EPROM) or microprocessor inside the ECU.

During the process of chip tuning, this database, programmed on to the EPROM (Chip) and processor inside the ECU, is optimised. All relevant patterns and identifiers for injection and ignition timing, boost control, load limitation and exhaust emissions, are being monitored over the entire rpm range of the engine and then changed within certain limits, dependent on load and engine-rpm, so that maximum horsepower and torque output can safely be increased.

Depending on the car make and model, turbocharged engines (petrol or diesel) will see an increase of horsepower and torque of 20% to 40% - and for normally aspirated engines 7% to 12% is realistic. In both cases acceleration, top end speed and elasticity improve significantly. Correct chip tuning will not have any effect on the durability of the engine. Note that correct servicing and normal car care are recommended – this applies to both tuned and standard cars.

ECU Functions

Retarding and advancing ignition timing for economic and efficient fuel combustion, it is important under all possible driving conditions, to compute the correct ignition timing in relation to engine-rpm, load and other relevant parameters. For diesel engines the right injection timing (pump timing) is most important, especially on the latest common rail turbo diesel engines that utilise extremely high rail pressure.

Dwell control

Dependent on engine rpm - the time between ignition trigger signals varies. To ensure constant ignition energy it requires a certain Primary Current to flow through the windings of the ignition coil. To sufficiently build up a magnetic field inside the coil requires time. The time delay from switching to interrupting the primary circuit has great influence on the voltage induction into the secondary circuit of the ignition coil the higher the engine speed, the shorter the delay from switching to interrupting the primary circuit, the less energy is inducted into the secondary circuit. Careful tuning prevents misfire in this situation.

Detonation detection

Modern engines normally use a high compression ratio in order to achieve higher torque output and better fuel economy. Engines with high compression ratios have a higher risk of uncontrolled combustion, especially under high loads running at high rpm. Detonation is unwanted at any time. Where detonation is detected, the ECU will retard the ignition timing for the particular cylinder. On tuned engines, care is taken to ensure detonation non-existent throughout the rev range.

Fuel injection

The new engine tuning takes into account air-mass (airflow) signals, rpm, load and correctional factors such as ambient air temp as well as coolant temperature etc... The ECU mapping determines the required fuel quantity and injection timing based on the newly set parameters. This improves fuel economy and reduces exhaust emissions and is responsible for a higher specific engine output. Tuned engines will have these parameters enhanced, resulting in crisper throttle response, higher power output and smoother running.

Lambda control

Another important correctional factor during the remap is the Lambda-signal. The Lambda sensor located in the exhaust system constantly measures the remaining oxygen in the exhaust gases. This signal is used by the ECU under all driving conditions. Maintaining a safe Lambda through ECU tuning that ensures cooler combustion chambers with optimum fuel delivery is vital when maximising torque and power.

Boost control

On cars with turbocharged engines, the ECU calculates, in reference to load indication, the pressure and the required air charge volume and adjusts, depending on the corresponding sensor signals, the appropriate boost at a given rpm and throttle position. When chip tuning a turbo engine, these parameters are recalibrated to optimise power and torque delivery to ensure strong torque at all rpm points.

Top Speed Governor

Chip tuning will remove this limiter where present unless the customer specifies otherwise.

Diesel

Diesel chip tuning is unique in that fuel delivery, fuel quantity, fuel pressure and fuel timing; combined with throttle position, boost pressure and torque limiters are recalibrated during ECU remapping to achieve very significant torque and efficiency gains. Far more so than on any other engine type.

Vehicle Type, Transmission Version and Power Train

Chip tuning for each vehicle is very specific. Each tune is designed to work optimally with the car it is being applied to. The car's engine configuration, transmission type and drive train are important in determining the end tune. The vehicle's characteristics, strengths and weaknesses are taken into consideration when tuning.

Emissions and Fuel

We recommend the use of 98 octane petrol for the best results. Use of 95 octane petrol is fine in almost all cases, however, there may be a reduction in maximum torque using this fuel. Do not use 91 octane in any car, not even your lawn mower. Chiptuning NZ performance tuning complies with EU Emissions Regulations – unless otherwise specified.

Software Updates

Naturally, advances in software are made over time. As we make improvements to our performance tuning software, these are applied to the cars we tune to achieve the best performance result possible.

Cautions

It soon becomes clear why each ECU must be individually programmed with correct software to achieve maximum reliability, safe gains and drivability. So please be warned of products purporting to do what chip tuning does by fitting, for example, a "tuning box", switchable "power booster" or offering prices that are too good to be true – usually found on online auctions. These devices, at best, do nothing. But because they can interfere with the data transfer to and from the ECU, disturbances occur within the entire system, which in many cases has led to severe engine damage and vehicle faults.

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