Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Engine Control Unit shopping experience:

1. Compare - without doubt the biggest advantage that the Engine Control Unit offers shoppers today is the ability to compare thousands of Engine Control Unit at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.

2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about

3. Testimonials - don't know anybody that has bought a Engine Control Unit? Wrong! If the Engine Control Unit is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.

4. Questions - Got a question about Engine Control Unit then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....

5. Reputation - Never heard of the company selling Engine Control Unit? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Engine Control Unit and build up a picture of their reputation for sales, returns, customer service, delivery etc.

6. Returns - still worried that even after all of the above your Engine Control Unit wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.

7. Feedback - happy with your Engine Control Unit then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.

8. Security - check for the yellow padlock on the Engine Control Unit site before you buy, and the s after http:/ /i.e. https:// = a secure site

9. Contact - got a question about Engine Control Unit, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.

10. Payment - ready to pay for your Engine Control Unit, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.

An engine control unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle. More advanced ECUs found on most modern cars also control the ignition timing, variable valve timing (VVT), the level of boost maintained by the turbocharger (in turbocharged cars), and control other peripherals.

ECUs determine the quantity of fuel, ignition timing and other parameters by monitoring the engine through sensors. These can include, MAP sensor, throttle position sensor, air temperature sensor, oxygen sensor and many others.

Before ECUs most engine parameters were fixed. The quantity of fuel per cylinder per engine cycle was determined by a carburetor or injector pump.



ECU operation Control of fuel injection For an engine with fuel injection, an ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up).

Control of ignition timing A Spark Ignition Engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy. If the ECU detects Engine knocking, a condition which is potentially destructive to engines, and "judges" it to be the result of the ignition timing being too early in the compression stroke, it will delay (retard) the timing of the spark to prevent this.

A second, more common source, cause, of knock/ping is operating the engine in too low of an RPM range for the "work" requirement of the moment. In this case the knock/ping results from the piston not being able to move downward as fast as the flame front is expanding.

But this latter mostly applies only to manual transmission equipped vehicles.The ECU controlling an automatic transmission would simply downshift thetransmission were this the cause of knock/ping.

Control of variable valve timing Some engines have Variable Valve Timing. In such an engine, the ECU controls the time in the engine cycle at which the valves open. The valves are usually opened later at higher speed than at lower speed. This can optimise the flow of air into the cylinder, increasing power and economy.

Programmable ECUs A special category of ECUs are those which are programmable. These units do not have a fixed behavior, but 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, and conversion to run on alternative 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 or USB cable, while the engine is running.

The programmable ECU may control fuel injection into each cylinder. This varies depending on the engine's RPM and the position of the gas pedal (or the MAP sensor). 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 a gas pedal position (or the throttle position sensor, as it is called). In this cell a number corresponding to the amount of fuel to be injected is entered.

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.

Other parameters that are often mappable are:

Some of the more advanced race ECUs include functionality such as launch control, limiting the power of the engine in first gear to avoid burnouts. Other examples of advanced functions are:

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 Mbytes.

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, CANbus.

ECU flashing Many recent (around 1996 or newer) cars use OBD-II ECUs that are sometimes capable of having their programming changed through the OBD port. Automotive enthusiasts with modern cars take advantage of this technology when tuning their engines. Rather than use an entire new engine management system, one can use the appropriate software to adjust the factory equipped computer. By doing so, it is possible to retain all stock functions and wiring while using a custom tuned program. This should not be confused with "chip tuning", where the owner has ECU ROM physically replaced with a different one -- no hardware modification is (usually) involved with flashing ECUs, although special equipment is required.

Factory engine management systems often have similar controls as aftermarket units intended for racing, such as 3-dimensional timing and fuel control maps. They generally do not have the ability to control extra ancillary devices, such as variable valve timing if the factory vehicle was a fixed geometry camshaft or boost control if the factory car was not turbocharged.

History Early ECUs Early ECU designs were based more on analogue computer circuitry. It was not until around 1987 that digital electronics and embedded system microprocessor systems became fast enough to process engine parameters in real time. The first such systems were introduced into racing engines such as those used for Formula One, but it was not long before these found their way into everyday automobile. Haltech Engine Management Systems based out of Sydney Australia are generally credited as having pioneered the programmable engine management system. It was in 1986 that they released the first laptop programmable engine management system called the F3. This system was a fuel only controller meaning it controlled only the fuel injection, but fuel and ignition controllers were only a few short years away.

Hybrid digital designs A hybrid digital design was popular in the mid-'80s. This used analogue techniques to measure and process input parameters from the engine, then used a look-up table stored in a digital Read-only memory chip to yield precomputed output values. Later systems compute these outputs dynamically. The ROM type of system is amenable to engine tuning if one knows the system well. The disadvantage of such systems is that the precomputed values are only optimal for an idealised, new engine. As the engine wears, the system is less able to compensate than a CPU based system.

Sophisticated engine management systems receive inputs from other sources, and control other parts of the engine; for instance, some variable valve timing systems are electronically controlled, and turbocharger wastegates can also be managed. They also may communicate with Transmission Control Unit or directly interface electronically-controlled automatic transmissions, traction control systems, and the like. The Controller Area Network or CAN bus automotive network is often used to achieve communication between these devices.

Modern ECUs Modern ECUs use a microprocessor which can process the inputs from the engine sensors in real time. An electronic control unit contains the hardware and software (firmware). The hardware consists of electronic components on a printed circuit board (PCB). The main component on this circuit board is a cpu (CPU). The software is stored in the microcontroller or other chips on the PCB, typically in EPROMs or flash memory so the CPU can be re-programmed by uploading updated code. This is also referred to as an (electronic) Engine Management System (EMS).

Other applications Such systems are used for many internal combustion engines in other applications. In aeronautical applications, the systems are known as "FADECs" (Full Authority Digital Engine Controls). This kind of electronic control is less common in piston-engined fixed-wing aircrafts than in automobiles, because of the large costs of certifying parts for aviation use, relatively small demand, and the consequent stagnation of technological innovation in this market. Also, a Carburetor engine with Magneto (electrical) ignition and a gravity feed fuel system does not require any electrical power to run, which is a safety bonus.

ECU failures As usually occurs with a technology shift, computer-controlled engine management has replaced old failure modes with new ones. With advanced age, a failing ECU can cause seemingly random starting and driveability faults. For example, a vehicle may refuse to start when cranked with the starter motor, but may respond easily to a push start. Failing electrolytic capacitors in the ECU no longer smooth the power supply to the microprocessor, and the varying load on the starter motor causes sufficient line voltage fluctuation that the computer reboots repeatedly while attempting to start the engine. An industry has evolved to refurbish ECUs with this and other types of failures related to age and use.

See also

External links

Manufacturers of Aftermarket ECUs

Open source engine management systems:

DIY engine management systems:

An engine control unit (ECU) is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle. More advanced ECUs found on most modern cars also control the ignition timing, variable valve timing (VVT), the level of boost maintained by the turbocharger (in turbocharged cars), and control other peripherals.

ECUs determine the quantity of fuel, ignition timing and other parameters by monitoring the engine through sensors. These can include, MAP sensor, throttle position sensor, air temperature sensor, oxygen sensor and many others.

Before ECUs most engine parameters were fixed. The quantity of fuel per cylinder per engine cycle was determined by a carburetor or injector pump.



ECU operation Control of fuel injection For an engine with fuel injection, an ECU will determine the quantity of fuel to inject based on a number of parameters. If the throttle pedal is pressed further down, this will open the throttle body and allow more air to be pulled into the engine. The ECU will inject more fuel according to how much air is passing into the engine. If the engine has not warmed up yet, more fuel will be injected (causing the engine to run slightly 'rich' until the engine warms up).

Control of ignition timing A Spark Ignition Engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy. If the ECU detects Engine knocking, a condition which is potentially destructive to engines, and "judges" it to be the result of the ignition timing being too early in the compression stroke, it will delay (retard) the timing of the spark to prevent this.

A second, more common source, cause, of knock/ping is operating the engine in too low of an RPM range for the "work" requirement of the moment. In this case the knock/ping results from the piston not being able to move downward as fast as the flame front is expanding.

But this latter mostly applies only to manual transmission equipped vehicles.The ECU controlling an automatic transmission would simply downshift thetransmission were this the cause of knock/ping.

Control of variable valve timing Some engines have Variable Valve Timing. In such an engine, the ECU controls the time in the engine cycle at which the valves open. The valves are usually opened later at higher speed than at lower speed. This can optimise the flow of air into the cylinder, increasing power and economy.

Programmable ECUs A special category of ECUs are those which are programmable. These units do not have a fixed behavior, but 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, and conversion to run on alternative 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 or USB cable, while the engine is running.

The programmable ECU may control fuel injection into each cylinder. This varies depending on the engine's RPM and the position of the gas pedal (or the MAP sensor). 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 a gas pedal position (or the throttle position sensor, as it is called). In this cell a number corresponding to the amount of fuel to be injected is entered.

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.

Other parameters that are often mappable are:

Some of the more advanced race ECUs include functionality such as launch control, limiting the power of the engine in first gear to avoid burnouts. Other examples of advanced functions are:

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 Mbytes.

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, CANbus.

ECU flashing Many recent (around 1996 or newer) cars use OBD-II ECUs that are sometimes capable of having their programming changed through the OBD port. Automotive enthusiasts with modern cars take advantage of this technology when tuning their engines. Rather than use an entire new engine management system, one can use the appropriate software to adjust the factory equipped computer. By doing so, it is possible to retain all stock functions and wiring while using a custom tuned program. This should not be confused with "chip tuning", where the owner has ECU ROM physically replaced with a different one -- no hardware modification is (usually) involved with flashing ECUs, although special equipment is required.

Factory engine management systems often have similar controls as aftermarket units intended for racing, such as 3-dimensional timing and fuel control maps. They generally do not have the ability to control extra ancillary devices, such as variable valve timing if the factory vehicle was a fixed geometry camshaft or boost control if the factory car was not turbocharged.

History Early ECUs Early ECU designs were based more on analogue computer circuitry. It was not until around 1987 that digital electronics and embedded system microprocessor systems became fast enough to process engine parameters in real time. The first such systems were introduced into racing engines such as those used for Formula One, but it was not long before these found their way into everyday automobile. Haltech Engine Management Systems based out of Sydney Australia are generally credited as having pioneered the programmable engine management system. It was in 1986 that they released the first laptop programmable engine management system called the F3. This system was a fuel only controller meaning it controlled only the fuel injection, but fuel and ignition controllers were only a few short years away.

Hybrid digital designs A hybrid digital design was popular in the mid-'80s. This used analogue techniques to measure and process input parameters from the engine, then used a look-up table stored in a digital Read-only memory chip to yield precomputed output values. Later systems compute these outputs dynamically. The ROM type of system is amenable to engine tuning if one knows the system well. The disadvantage of such systems is that the precomputed values are only optimal for an idealised, new engine. As the engine wears, the system is less able to compensate than a CPU based system.

Sophisticated engine management systems receive inputs from other sources, and control other parts of the engine; for instance, some variable valve timing systems are electronically controlled, and turbocharger wastegates can also be managed. They also may communicate with Transmission Control Unit or directly interface electronically-controlled automatic transmissions, traction control systems, and the like. The Controller Area Network or CAN bus automotive network is often used to achieve communication between these devices.

Modern ECUs Modern ECUs use a microprocessor which can process the inputs from the engine sensors in real time. An electronic control unit contains the hardware and software (firmware). The hardware consists of electronic components on a printed circuit board (PCB). The main component on this circuit board is a cpu (CPU). The software is stored in the microcontroller or other chips on the PCB, typically in EPROMs or flash memory so the CPU can be re-programmed by uploading updated code. This is also referred to as an (electronic) Engine Management System (EMS).

Other applications Such systems are used for many internal combustion engines in other applications. In aeronautical applications, the systems are known as "FADECs" (Full Authority Digital Engine Controls). This kind of electronic control is less common in piston-engined fixed-wing aircrafts than in automobiles, because of the large costs of certifying parts for aviation use, relatively small demand, and the consequent stagnation of technological innovation in this market. Also, a Carburetor engine with Magneto (electrical) ignition and a gravity feed fuel system does not require any electrical power to run, which is a safety bonus.

ECU failures As usually occurs with a technology shift, computer-controlled engine management has replaced old failure modes with new ones. With advanced age, a failing ECU can cause seemingly random starting and driveability faults. For example, a vehicle may refuse to start when cranked with the starter motor, but may respond easily to a push start. Failing electrolytic capacitors in the ECU no longer smooth the power supply to the microprocessor, and the varying load on the starter motor causes sufficient line voltage fluctuation that the computer reboots repeatedly while attempting to start the engine. An industry has evolved to refurbish ECUs with this and other types of failures related to age and use.

See also

External links

Manufacturers of Aftermarket ECUs

Open source engine management systems:

DIY engine management systems:



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Engine Control Unit



 
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