George, Western Cape, South Africa

Engine Management and Tuning for Economy

Fuel Optimisation for Economy

Chip tuning refers to changing or modifying an erasable programmable read only memory chip in an automobile’s or other vehicle’s electronic control unit (ECU) to achieve superior performance, whether it be more power, cleaner emissions, or better Fuel efficiency. This makes use of the engine manufacturer to generally use a conservative electronic control unit map to allow for individual engine variations as well as infrequent servicing and poor-quality fuel. Vehicles with a remapped electronic control unit may be more sensitive to fuel quality and service schedules.  See this clip and you will have a better understanding of flash tune/chip tune for optimization and fuel saving www.optican.net www.obd-tuning.com This was done with early engine computers in the 1980s and 1990s. Today, the term chip tuning can be misleading, as people will often use it to describe ECU tuning that does not involve swapping the chip. Modern electronic control units can be tuned by simply updating their software through a standard interface, such as On Board Diagnostics. This procedure is commonly referred to as engine or electronic control unit tuning. Electronic control units are a relatively recent addition to the automobile, having first appeared in the late 1970s. As technology advanced, so did the electronics that go into cars. The electronic control unit in a modern automobile, together with advanced engine technology, makes it possible to control many aspects of the engine’s operation, such as spark timing and fuel injection. The electronic control unit may also control electronic throttle control (drive-by-wire), poppet valve timing, boost control (inturbocharged engines), Anti-lock braking system, the automatic transmission, speed governor (if equipped), and the Electronic Stability Control system. Performance gains are realized by adjusting the ignition timing advance. Different timing may result in better performance. However, to cope with advanced timing, one must run high-octane gasoline to avoid pre-ignition detonation or pinging. Manufacturers design for a specific timing and this may limit performance accordingly. In addition, changing fuel maps to coincide with the stoichiometric ratio for gasoline combustion may also realize performance increase. Most manufacturers tune for optimum emissions (running rich to protect the catalytic converter) and fuel economy purposes which can limit performance. Cars with a turbo fitted can have the requested and allowable boost levels raised, these applications usually have the most effect if the turbo fitted is a low pressure turbo which leaves the most room for improvement. Another reason to change the electronic control unit map is if there are engine, intake, or exhaust modifications to the car. These “bolt-on” modifications alter the way that the engine flows, often causing the air to fuel ratio to change. Without re-mapping the fuel tables, some of the performance gains from the modifications may not be realized. A poorly tuned electronic control unit can result in decreased performance, driveability, and may even cause engine damage. The most common way to “upgrade” the electronic control unit is using either plug in modules as mentioned above or using a specialist tuner who will use an On Board Diagnostics Flash tool. These devices generally plug into the diagnostic port although in some cases the reprogramming is done directly on the circuit board. Maps are supplied by tuners. An alternative to modifying the on-board chip is adding an external device, often known as a tuning box. The abilities of the external devices generally reflect on-board chip modifications, with the advantage that they can be easily removed to restore the vehicle to standard. Adding an external tuning box is generally only possible on modern engines with external management ports.[1]

Engine Management

Engine Management can be anything from OE ecu to aftermarket,piggy back or altering the information on the existing ecu,be it any of the above the end result is to be able to tune the engine to get the best from it . A special category of ECUs are those which are programmable. These units do not have a fixed behaviour and can be reprogrammed by the user. Programmable ECUs are required where significant aftermarket modifications have been made to a vehicle’s engine. Examples include adding or changing of a turbocharger, adding or changing of an intercooler, changing of the exhaust system or a conversion to run onalternative fuel. As a consequence of these changes, the old ECU may not provide appropriate control for the new configuration. In these situations, a programmable ECU can be wired in. These can be programmed/mapped with a laptop connected using a serial orUSB cable, while the engine is running. The programmable ECU may control the amount of fuel to be injected into each cylinder. This varies depending on the engine’s RPM and the position of the accelerator pedal (or the manifold air pressure). The engine tuner can adjust this by bringing up a spreadsheet-like page on the laptop where each cell represents an intersection between a specific RPM value and an accelerator pedal position (or the throttle position, as it is called). In this cell a number corresponding to the amount of fuel to be injected is entered. This spreadsheet is often referred to as a fuel table or fuel map. By modifying these values while monitoring the exhausts using a wide band lambda probe to see if the engine runs rich or lean, the tuner can find the optimal amount of fuel to inject to the engine at every different combination of RPM and throttle position. This process is often carried out at a dynamometer, giving the tuner a controlled environment to work in. An engine dynamometer gives a more precise calibration for racing applications. Tuners often utilize a chassis dynamometer for street and other high performance applications. Other parameters that are often mappable are:
  • Ignition Timing: Defines at what point in the engine cycle the spark plug should fire for each cylinder. Modern systems allow for individual trim on each cylinder for per-cylinder optimization of the ignition timing.
  • Rev. limit: Defines the maximum RPM that the engine is allowed to reach. After this fuel and/or ignition is cut. Some vehicles have a “soft” cut-off before the “hard” cut-off. This “soft cut” generally functions by retarding ignition timing to reduce power output and thereby slow the acceleration rate just before the “hard cut” is hit.
  • Water temperature correction: Allows for additional fuel to be added when the engine is cold, such as in a winter cold-start scenario or when the engine is dangerously hot, to allow for additional cylinder cooling (though not in a very efficient manner, as an emergency only).
  • Transient fueling: Tells the ECU to add a specific amount of fuel when throttle is applied. The is referred to as “acceleration enrichment”.
  • Low fuel pressure modifier: Tells the ECU to increase the injector fire time to compensate for an increase or loss of fuel pressure.
  • Closed loop lambda: Lets the ECU monitor a permanently installed lambda probe and modify the fueling to achieve the targeted air/fuel ratio desired. This is often the stoichiometric (ideal) air fuel ratio, which on traditional petrol (gasoline) powered vehicles this air:fuel ratio is 14.7:1. This can also be a much richer ratio for when the engine is under high load, or possibly a leaner ratio for when the engine is operating under low load cruise conditions for maximum fuel efficiency.
Some of the more advanced standalone/race ECUs include functionality such as launch control, operating as a rev limiter while the car is at the starting line to keep the engine revs in a ‘sweet spot’, waiting for the clutch to be released to launch the car as quickly and efficiently as possible. Other examples of advanced functions are:
  • Wastegate control: Controls the behavior of a turbocharger‘s wastegate, controlling boost. This can be mapped to command a specific duty cycle on the valve, or can use a PID based closed-loop control algorithm.
  • Staged injection: Allows for an additional injector per cylinder, used to get a finer fuel injection control and atomization over a wide RPM range. An example being the use of small injectors for smooth idle and low load conditions, and a second, larger set of injectors that are ‘staged in’ at higher loads, such as when the turbo boost climbs above a set point.
  • Variable cam timing: Allows for control variable intake and exhaust cams (VVT), mapping the exact advance/retard curve positioning the camshafts for maximum benefit at all load/rpm positions in the map. This functionality is often used to optimize power output at high load/rpms, and to maximize fuel efficiency and emissions as lower loads/rpms.
  • Gear control: Tells the ECU to cut ignition during (sequential gearbox) upshifts or blip the throttle during downshifts.
A race ECU is often equipped with a data logger recording all sensors for later analysis using special software in a PC. This can be useful to track down engine stalls, misfires or other undesired behaviors during a race by downloading the log data and looking for anomalies after the event. The data logger usually has a capacity between 0.5 and 16 megabytes. In order to communicate with the driver, a race ECU can often be connected to a “data stack”, which is a simple dash board presenting the driver with the current RPM, speed and other basic engine data. These race stacks, which are almost always digital, talk to the ECU using one of several proprietary protocols running over RS232 or CANbus, connecting to the DLC connector (Data Link Connector) usually located on the underside of the dash, inline with the steering wheel