ECUGlossary
ECUGlossary
| Analog inputs | Used in ECU's to measure the signals from sensor. Signals like TPS signals are measured with Analog inputs and measured with Analog to Digital converters. Resolution of the 8-bit converter is up to 255, 10-bit up to 1024. |
| Anti-Lag | Used in Turbo applications to increase turbo pressure by retarding ignition and adding fuel. This increases the turbo speeds, pressure and engine power. |
| Automated tuning | Many modern ECU's can tune the fuel maps automatically by reading the WB 02 sensor and adjusting the injection time accordingly. With this feature map can be tuned very fast and might save you money in the end not having to spend so much time in the dyno. |
| Batch Injection | Injection type, where 2 or more injectors are fired at the same time |
| CAN bus | CAN bus, (Controller Area Network) is up to 1MBps communication line used in modern ECU's and peripherals like Drive by wire throttles and displays. Can also be used for data download from ECU. |
| CDI Ignition | Capacitive Discharge Ignition. Useful in Turbo applications where fast and strong spark can be given. |
| Closed Loop Control | Term is typically used with 02 sensors, but is also used with PID controllers. In closed loop systems current output is measured and with this information controller behavior is changed. In case of 02 sensors, air fuel ratio of the combustion is measured. If measurement was >14.7, mixture was lean and more fuel is injected during next injection cycle. Less fuel would be injected if measurement would be less than 14.7. Closed loop means here that length of fuel injection is defined from the measured AFR. |
| Coil On Plug | Used in modern applications to reduce the number of ignition components. Coils are typically mounted just above the spark plugs, therefore eliminating the need of spark plug wires. COP's are typically used with direct ignition. Some coils are also fitted with internal igniters and can be controlled directly by the ECU. |
| Direct Ignition | First car with direct ignition was Saab 9000 already in 1990. It also had Ion sensing at that time. With direct ignition the use of spark wires and distributors can be eliminated. |
| Drive By Wire | Drive by Wire technology uses an electronic throttle instead of the traditional mechanical system, interpreting pedal input from the driver via sensors while controlling a throttle motor. This feature is optional for many ECU's and adds to purchase price if needed. |
| Dwell table | Dwell refers to the period how long ignition coils are charged before ignition is fired. Too long dwell time can destroy coils, so care must be taken. Longer dwell periods can be used in low battery situations to improve spark. Adjustable dwell table is useful so that spark output can be optimized. |
| Injector Phasing | Used primarily with Sequential injection setup. Defines when injection is performed. This is helpful in tuning for emissions. |
| Ion sensing | Has been used by Saab already from early 1990's to detect detonation. Ionization voltage is measured across the spark plug gap to determine combustion efficiency. |
| Knock control | System where engine detonation can be detected in order to avoid harm to the engine. When knock is detected, ignition is typically retarded and fuel added by the ECU. Typical knock sensor is a piezo sensor installed into engine block. These sensors have sometimes trouble in detecting knock in engines with noisy valve trains. Other methods include cylinder pressure sensing with special pressure sensors directly installed into the combustion chamber, Ion sensing using the spark plug and pressure sensors installed under the spark plug. |
| Peak and Hold Injectors | Injectors with less than 4ohms coil resistance. Typically used in racing applications because can be opened faster than saturated injectors. Some ECU's don't have support for Peak and Hold injectors and accessory is needed. Peak and Hold injectors have typically higher flow rates compared to saturated injectors. |
| Launch Control | Launch control is a means of allowing the ECU control of the engine power output during the start phase to provide the best possible traction from the start line. The driver maintains full throttle at all times, when stationary with the clutch depressed. As soon as the car begins to move the ECU reduces power output by first retarding the ignition advance and if this still does not control the rpm it will cut one or all cylinders as required to keep the engine RPM to the limits set in this section. An un-driven wheel speed sensor is required and a push button switch on the dashboard to activate the Launch Control. The driver comes to the start line, depresses the clutch and engages gear. The launch control button is pressed and presses the throttle fully open. The engine will be held at the launch control rev limit. When the clutch is released the ECU will control the engine revs to maintain the target slip percentage until the turn off speed is reached. After this time it will allow the engine to run free until the button is pressed again. |
| MAP Sensor | Sensor, which is used to sense intake manifold pressure to ECU. MAP is used with Turbo applications since is intake air pressure can be measured with it. Also recommended for Naturally Aspirated engines when Idle Control Valve is being used. |
| Narrow band 02 sensor | Traditional 02 sensor can only sense AFR's close to stoichometric 14.7 so that closed loop function can be performed. Fuel map tuning using Narrow band 02 sensor is not really possible, map could be tuned only to 14.7 AFR. For this reason WB02 sensor was created. NB 02 sensor is a good troubleshooting tool when tuning closed loop. |
| Onboard data logging | In many cases optional, so take this into consideration when deciding what ECU to purchase. Onboard data logging is very useful especially in race applications where installing an onboard PC's is not an option. Data logging is typically activated after a certain RPM is reached or switch is activated. Data is recorded and can be then downloaded when car has returned to pits. |
| Onboard WB 02 Sensors | In many cases, WB02 sensor drivers are not installed inside the ECU and there fore external controller like PLX is needed. In some cases hardware is inside the ECU, but WB02 is optional. This should be considered when deciding what ECU to buy since this will increase the price. Some devices can support multiple WB 02 sensors, which is useful in V-engine applications. |
| PWM outputs | PWM outputs can be used typically to control Idle Control valves and Turbo waste gates. PWM is a signal where the output changes the state between high and low depending what is the duty cycle. 100% typically means that signal is constantly high, 0% constantly low. |
| Saturated Injectors | Injectors with more than 4ohm coil resistance. Many OEM applications use these injectors since injectors are cheaper. Due to higher resistance these will draw less current and are typically supported by all ECU's having some type of injector driver onboard. |
| Sampling rate | Sampling rate defines how many times measurement is performed in certain time period. Typically this is measurements/second. If you use high sampling rates and you have limited amount of memory, recording time can be very short. On the other had if sampling rate is too low, it might be difficult to troubleshoot problems. Best solution is a solution where sampling rates can be defines for each channel separately. |
| Sequential Injection | Injection type, where fuel is injected to each cylinder individually and only once during engine cycle. Can be used to give better fuel control compared to batch injection and typically reduces emissions. Camshaft sensor is typically required for Sequential setup. |
| Switch inputs | Switch inputs are needed for ECU to sense the position of the switches like launch control, map position switch etc... Typically ECU's are equipped with pull-up resistors and there fore only switch to ground is needed. |
| Throttle Mapping | A called as alpha-N. Typically used in naturally aspirated engines and racing applications. Throttle position is measured by a potentiometer and this indicates the position of the throttle plates and how much air is entering to the engine. |
| Traction control | System, where engine power is limited when wheel speed difference is detected. |
| Waste Spark Ignition | Ignition type, where 2 or more spark plugs are fired at the same time. |
| WB 02 sensor | WB02 sensor is needed for exact AFR measurements and automated tuning functions are not possible without it. WB02 sensor can typically sense AFR ratios between 10 to 20, narrow band is only able to measure the AFR close to 14.7. |
| Wheel speed inputs | Wheel speed inputs are needed to sense the wheel speeds. This is typically required for speed detection, launch control, traction control and all other functions requiring the speed information. |
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