Which is commonly encountered at idle and even during cruise conditions. So, before jumping into the more technical stuff you at least need to have a basic understanding of the operation of modern fuel injectors. The bigger the injector, the more pronounced and widespread the nonlinearity becomes.
They then use these renderings to make an estimation of how much fuel came out. At the OE-level, the flow and dead time matching process is much more lenient. The average high quality aftermarket fuel injector manufacturer flow matches within 2 to 3-percent, but cannot test for offset in production quantities. The red box represents the OE-level of variance allowed when matching is done by manufacturers like Bosch and Denso; green, the variance typical by the majority of the aftermarket; blue, the variance allowed by Fuel Injector Clinic.
Research And Development. An example of the raw hexadecimal code found in most modern automotive ECUs, read using the hex code disassembler and debugging software, IDA. This is the data that aftermarket engineers sift through to find addresses for important tables such as ignition timing, VVT, injector compensation, etc, which can then be used to build a single or multidimensional table in third party tuning software to make adjustments. The ECU in your vehicle automatically assumes that the fuel injectors operate on a linear line from a pulse width of 19 ms down to 0 ms, which is shown as the dotted red line on the graph below.
We highlighted the correct offset value in red. It should be noted that in order to download the Accesstuner software, Cobb requires you to at least have a basic understanding of ECU calibration. Finding The Outliers. No longer just matching sets in the linear zone to 1-percent in dynamic flow and 2-percent in offsets.
While still idling rich due to their large size, the car drove much more predictably and smoothly around town and at idle. Fuel Injector Clinic was able to collect valuable information from this test that will be used to further refine their injector matching process and better the industry as a whole.
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Engine Buildup. More Stories. Horsepower delivered to your inbox. Subscribe Now. We'll send you raw engine tech articles, news, features, and videos every week from EngineLabs.The ability to control a mechanical device electrically has done more to advance gasoline and diesel engine operation than anything else. One method to accomplish this is called the pulse width modulated PWM circuit. It is found in many places on modern engines and equipment.
An electronic fuel injector gas or diesel is the most common use of a PWM circuit, but it is not the only one. In most diesel applications, the exhaust gas recirculation valve is PWM controlled also. It does not end there. Shared theory of operation Since a PWM circuit does not know what it is controlling, the way it works and the diagnostics are the same.
The component being controlled needs to have a solenoid attached either integral or divorced. It is an electromagnet that works with a metal rod, plunger, or disk. When power is applied, the solenoid is energized, and the induced magnetic field works against the metal component usually inducing flow of what is being controlled. When the power is shut off, an internal spring then closes the device and flow stops. The part is turned on and off at a rapid pace. The control comes by altering the on and off time.
This is responsible for the ticking sound when operating. This is known as dwell. A control unit is usually identified as an ECU. It is the brain and handles the task of the duty cycle. In most — if not all — applications, the solenoid is supplied with system voltage, and the ground circuit is turned on and off by the ECU. Switching the ground is quieter electrically, which means cleaner. The ECU has drivers that can be considered an electronic switch with no moving parts.
Basic diagnostics The circuit will always have two wires power and ground. The solenoid has a specified resistance that can be confirmed by unplugging it and placing an ohm meter across the two terminals. To confirm if the ECU is commanding control, you need to employ either a test light or a noid light.
The test light can be attached in series between the two terminals and the circuit evoked. The light should pulse. A shorted solenoid can often damage the driver in the ECU.
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A fuel injection ECU system is an important part of a fuel injected engine because it serves several functions aside from regulating and maintaining the amount of fuel and air that the engine needs to increase horsepower. The Electronic Control Unit is an integral part of the EFI or the Electronic Fuel Injection, which is a type of fuel injection system that is now commonly used among cars.
EFI can be divided into 3 sub-systems: air induction system, fuel delivery system and the electronic control system. Aside from the ECU, this is also where you will find various sensors, fuel injector assemblies and any related fuel injection wiring.
A fuel injection ECU system has several functions. Probably one of the most important function of the ECU is it controls the fuel mixture used by the engine. This computer program receives several data and computes them to come up with the appropriate amount. The ECU of an Electronic Fuel Injection also determines when is the right time to deliver the air and fuel ratio to the engine.
This process is called injection duration or injection pulse width. Most cars also have a built in control system in their ECU for idle speed. Idle speed is controlled through the programmable throttle stop. Aside from idle speed, an ECU controls the ignition timing of an engine. This is done by adjusting the time when the spark ignition plug should be sparked, resulting in better power. The ECU system also controls the variable valve timing. This simply means that it controls when the valves will open.
This is done to increase performance and power of the car since the flow of air into the cylinder is maximized. Based on the data gathered by the ECU sensors, it can basically control the engine's speed, coolant temperature, throttle angle and exhaust oxygen content.
A fuel injection ECU works by pulsing or controlling the fuel injectors in the engine. This is done by switching the injector ground circuit on or off depending on what is required by the engine. If the injector ground circuit is turned on the fuel is sprayed at the back of the intake valve. When the fuel is sprayed, it mixes with the air. Due to the low pressures in the intake manifold, the fuel and air mixture then vaporizes. This is where the fuel injection ECU sensor works.
It gives a signal to the ECU to provide the right air and fuel ratio.Remember Me? What's New? Page 1 of 3 1 2 3 Last Jump to page: Results 1 to 20 of Thread: WTF Min injector pulse.
Thread Tools Show Printable Version. WTF Min injector pulse What is the point of having this?? I finaly discovered it was cause the min injector pulse was to high stock settings and stock injectors. IF the car is requesting a certain pulse width for the fueling it needs why do you have to add to it and make the car go rich to make it above the min value. Would the injectors not respond to a pulse less than a certain width? It takes time for a valve to open and close, if the pulse wasn't long enough, the valve may not have time to respond.
That parameter may be so the ECU does not try to send a pulse that is quicker than what the injector can respond to Originally Posted by Shifted.
Always Support Our Troops! EC is correct, GM have all the min pulse width stuff to compensate for the large non-linearity at very small pulse widths.
I count sheep in hex But isn't that the offset value table's job, not the Min PW? Seems like min doesn't compensate anything, it's just a clip limit? The short pulse and adder tables compensates the fuel delivery for a given pulse width in an attempt to keep it linear.
You are correct that the min pulse width is a clip, basically it is saying that below this number cannot be compensated so don't go below it. Who knows what the right numbers are Would you recomend changing the factory setting for min pulse width lower if need be or is that factory limit the lowest you should go to have consistent fueling. Im in the process of tuning my Ve table in open loop and im running really rich on decel cause of this.Testing Injector Pulsewidth on 5.0L Mustang
I do plan on turning DFCO back on once im happy with everything so its not a biggie but if possible i would like to lean it out a little so my ve will be spot on. I have also put in larger injectors I am tuning VE right now and have noticed that I am running at or so in decel.
Seem like I keep raising the Ve in those spots without awhole lot of sucess! Should have said lowering not raising. Last edited by Dragman; at PM. Fastest A4 Coupe Bolt On's Originally Posted by Dragman. Im running SVO 42 injectors. Would I multiply by 1. How do you know or find what your Inj.Remember Me?
What's New? Forum General information Lounge What is the frequency of typical injector pulse width? Results 1 to 7 of 7. Thread: What is the frequency of typical injector pulse width? November 19th, 1. What is the frequency of typical injector pulse width? I know that this isn't an electronics board, but I know that tuning and circuits aren't mutually exclusive. Looking to convert a v signal into PWM, and although I don't know how I will get there, I do know that one of the parameters will be the frequency of the pulse.
Not looking for direct injection, just normal injector frequency. Need it to signal a controller. November 21st, 2. November 23rd, 3. Two more please What duration? What ratio of high to low? November 23rd, 4.
The duration is the injector pulse width IPW, this varies with engine load and commanded fuel. Last edited by joecar; November 23rd, at PM. November 23rd, 5. I am trying to mimic a fuel injector, so I was just trying to figure out what info I would need to get it done. THe duration gets longer as load increases, but what would we be talking about here? November 23rd, 6. November 23rd, 7. All times are GMT The time now is PM. All rights reserved.The software has to allow the car to satisfy emissions requirements formiles, meet EPA fuel economy requirements and protect engines against abuse.
And there are dozens of other requirements to meet as well. The engine control unit uses a formula and a large number of lookup tables to determine the pulse width for given operating conditions. The equation will be a series of many factors multiplied by each other. Many of these factors will come from lookup tables.
We'll go through a simplified calculation of the fuel injector pulse width. In this example, our equation will only have three factors, whereas a real control system might have a hundred or more. In order to calculate the pulse width, the ECU first looks up the base pulse width in a lookup table. Base pulse width is a function of engine speed RPM and load which can be calculated from manifold absolute pressure.
Let's say the engine speed is 2, RPM and load is 4. We find the number at the intersection of 2, and 4, which is 8 milliseconds. In the next examples, A and B are parameters that come from sensors. Let's say that A is coolant temperature and B is oxygen level.
From this example, you can see how the control system makes adjustments. With parameter B as the level of oxygen in the exhaust, the lookup table for B is the point at which there is according to engine designers too much oxygen in the exhaust; and accordingly, the ECU cuts back on the fuel.
Real control systems may have more than parameters, each with its own lookup table. Some of the parameters even change over time in order to compensate for changes in the performance of engine components like the catalytic converter.
And depending on the engine speed, the ECU may have to do these calculations over a hundred times per second. Performance Chips This leads us to our discussion of performance chips. Now that we understand a little bit about how the control algorithms in the ECU work, we can understand what performance-chip makers do to get more power out of the engine.
Performance chips are made by aftermarket companies, and are used to boost engine power. There is a chip in the ECU that holds all of the lookup tables; the performance chip replaces this chip. The tables in the performance chip will contain values that result in higher fuel rates during certain driving conditions. For instance, they may supply more fuel at full throttle at every engine speed. They may also change the spark timing there are lookup tables for that, too.
Since the performance-chip makers are not as concerned with issues like reliability, mileage and emissions controls as the carmakers are, they use more aggressive settings in the fuel maps of their performance chips.
For more information on fuel injection systems and other automotive topics, check out the links on the next page.Which 1 actually supplies the power wire to the Injector? Car is a Olds. Cutlass Siera. The gas pedal in your car is connected to the throttle valve -- this is the valve that regulates how much air enters the engine.
So the gas pedal is really the air pedal. When you step on the gas pedal, the throttle valve opens up more, letting in more air.
How Fuel Injection Systems Work
The engine control unit ECU, the computer that controls all of the electronic components on your engine "sees" the throttle valve open and increases the fuel rate in anticipation of more air entering the engine. It is important to increase the fuel rate as soon as the throttle valve opens; otherwise, when the gas pedal is first pressed, there may be a hesitation as some air reaches the cylinders without enough fuel in it.
Sensors monitor the mass of air entering the engine, as well as the amount of oxygen in the exhaust. The ECU uses this information to fine-tune the fuel delivery so that the air-to-fuel ratio is just right.
Function of Fuel Injector Pulse Width
Its the puter, it does the thinking and it opens and closes the injectors, going by what all the sensors are telling it. For instance, when an engine is cold, the coolant sensor tells the computer to turn off some of the other sensors, and the computer then turns off the sensors and adds lots of gas, to keep the engine running when it is cold.
You see, cold gas does not burn good, so it takes more. With the sensors turned off, the computer runs the injectors rich, and the engine gets plenty of gas.
So, you see,it isn't just one that does the job, but a combination of them all. And the brain, the puter, is controlling it all. When you turn on the key, the computer gets the fuel pump to run for 2 seconds, opens up the injectors to get the gas, and sends current to the distributor to fire the sparkplugs. If after the 2 second spurt of gas, the engine doesn't start, the computer shuts down the pump, the injectors and you are not starting.
You then have to turn the key again, for another try. The 2 seconds is so that the fuel pump will not keep pumping gas into an engine if it is not running. And of course, the injectors will be shut off also, after the 2 seconds. So, it is the puter that is sending the signal to open the injectors, and start the pump.
It is like you putting your hand on a hot stove. Your hand doesn't pull away by itself, the signal goes to the brain, and your brain tells the hand, "it is hot" and your hand then moves. The ECU aka computer controls the fuel injectors.
It will ground or was it positive, forgot the injectors really quick. It is so quick that there is a special light called a noid light used to connect to the fuel injector connector to test this signal. How long to spray is determined by the ECU. What factors the ECU takes into consideration is based on its program and its inputs.
When one of these sensors go bad the ECU uses a predetermine value instead of the value from the sensor, since it's now dead. This is what's called a limp mode. That is when the check engine light comes on. Actually, the injector's typically have a constant power on one side, and the computer directly supplies the ground for as long or as short as it needs to depending on all the info from the sensors you mentioned.
The ECU controls the injectors. Probably other inputs too, can't remember all of them. Unplug an injector plug,plug the noid light into the harness and crank it over,if you can see a little light pulse in the noid then the injection trigger is working. The throttle sensor basically assesses the amount of air used, the ECM monitors temperature, humidity, speed, trans gearing, newer models measure tire pressure,