The Electronic Fuel Injection System Engineering Essay

The Electronic Fuel Injection System Engineering EssayThe Electronic Fuel Injection frame force out be divided into collar basic sub -systems. These are the elicit delivery system, transfer abstraction system, and the electronic control system.The can delivery system consists of the render tank, give the sack heart and soul, furnish filter, elicit delivery pipe ( evoke rail), fuel injector, fuel pressure regulator, and fuel return pipe.Fuel is delivered from the tank to the injector by means of an electric fuel pump. The pump is typically located in or near the fuel tank. Contaminants are filtered out by a high capacity in line fuel filter.Fuel is maintained at a constant pressure by means of a fuel pressure regulator. Any fuel which is not delivered to the consumption manifold by the injector is returned to the tank through a fuel return pipe.The Air Induction SystemThe air induction system consists of the air cleaner, air flow step, throttle valve, air usance chamber , in nonplus manifold runner, and intake valve.When the throttle valve is opened, air flows through the air cleaner, through the air flow meter (on L type systems), past the throttle valve, and through a well tuned intake manifold runner to the intake valve.Air delivered to the locomotive locomotive engine is a wait on of driver demand. As the throttle valve is opened further, more air is allowed to enter the engine cylinders.Mostly the L type EFI system measures air flow immediately by using an air flow meter. The D type EFI system measures air flow indirectly by monitoring the pressure in the intake manifold.Electronic Control SystemThe electronic control system consists of various engine sensors, Electronic Control Unit (ECU), fuel injector assemblies, and related wiring.The ECU determines precisely how frequently fuel needs to be delivered by the injector by monitoring the engine sensors.The ECU turns the injectors on for a precise sum total of time, referred to as guessw ork flash breadth or injection eon, to deliver the proper air/fuel ratio to the engine.Basic System OperationAir enters the engine through the air induction system where it is measured by the air flow meter. As the air flows into the cylinder, fuel is mixed into the air by the fuel injector.Fuel injectors are arranged in the intake manifold behind each intake valve. The injectors are electrical solenoids which are operated by the ECU.The ECU pulses the injector by switching the injector ground circuit on and off.When the injector is turned on, it opens, spraying atomized fuel at the back side of the intake valve.As fuel is sprayed into the intake airstream, it mixes with the incoming air and vaporizes due to the low pressures in the intake manifold. The ECU signals the injector to deliver just enough fuel to achieve an ideal air/fuel ratio of 14.71, often referred to as stoichiometry.The precise aggregate of fuel delivered to the engine is a function of ECU control.The ECU dete rmines the basic injection quantity based upon measured intake air volume and engine rpm.Depending on engine direct conditions, injection quantity will vary. The ECU monitors variables such as coolant temperature, engine speed, throttle angle, and exhaust oxygen content and makes injection emendions which determine final injection quantity.WHAT ONE HAS TO DO TO CONVERT CARB TO EFI IN CASE OF A CARHeres what is necessitate for complete conversionEFI head and intake manifold with everything still attached.crossing tube, MAF sensor and air boxFuel tank with fuel pumpEntire wiring harness from the car.EFI computerEFI distri furtherorEFI coil/igniterEFI come close set in the dashKnock sensor, main relayAnything else that was attached to the wiring harnessOther things which are also essentialLC Engineering EFI master camFel Pro head gasket setFluidsThese are the stepsOut with the oldAir cleaner offvalve cover off level offHead on the bench with the intake removed.EFI intake and EFI h eadCarb head and EFI components installedCertain small things that we found were different wereThere was some sort of smog fraud bolted to where the EFI fuel filter goes. It isnt mathematical functiond with EFI and was discarded as were the air tubes that go above the header.The high pressure fuel line has to be either do or salvaged.The vacuum hose for the brake booster is different between carb and EFI.The upper radiator hose is different between carb and EFIThe good thing is that two of the plugs that go into the computer can be disconnected and are only go to the engine. So, if you unplug these from the intake, then pull the intake intact. The third plug has the power and other(a) things going to it for the EFI.All game is to take your time and check each wire coming out of the computer.There seems to be only 3 components extraneous of the normal EFI stuff.The main EFI relay located in the interior fuse panel at a lower place the drivers side dash. The circuit opening rela y located under the passenger side dash. This is controlled by the MAF sensor and turns on and off the fuel pump. It is also tied into the main EFI relay.The solenoid resistor is connected to a switched power germ (IGN) and goes to the fuel injectors. This is located in the engine compartment passneger side.Pretty much, the only thing that is not straight forward is how these three components are wired.Mathematical Formulation sink of FormMost EFI systems have a standard set of sensors. These includeTheBarometric obligate (BARO) Sensor, which provides the ECU with the atmospheric air pressure reading.TheEngine Coolant Temperature (ECT) Sensor, which provides the ECU with the engines current operate temperature. This is important because fuel vaporization varies for different engine temperatures. A cold engine requires more fuel while a hot engine requires less.The inlet Air Temperature (IAT) Sensor, which the ECU needs to take into account when determining pulse duration.TheMass Air Flow (MAF) Sensor, which is a tube positioned after the air filter in the air intake duct. The MAF sensor has a fine platinum wire that spans across the tube. The wire is heated by electrical current to maintain a constant temperature above ambient. The air flow past the wire cools the wire and more current is required to maintain the constant temperature. Thus, the amount of current required to maintain the constant temperature indicates the air flow rate. The air flow rate is divided by RPM to determine the pulse duration.TheManifold Absolute Pressure (MAP) Sensor, which uses manifold vacuum to measure engine load. An EFI system that uses a MAP sensor does not require a MAF sensor as it can use the input from the MAP sensor to determine the required pulse duration.TheOxygen Sensor (O2S), which is used to measure the amount of oxygen that is not consumed during combustion. This is important for the correct operation of the catalyst converter and is used for emissions control ra ther than performance or economy. The O2S is located in the exhaust system and is an after-the-fact measure of the air/fuel ratio. Too much unburnt fuel in the exhaust indicates a lean mixture while too little oxygen indicates a rich mixture.TheCrankshaft perspective (CKP) Sensor, which is important for timing purposes as it tells the ECU which spark plug to fire and which injector to open at any given point in theOtto cycle.TheThrottle Position (TP) Sensor, which is some other important sensor as the throttle position and the rate of change in the throttle position indicates the what the diver wants the car to do. cap of FormThe modifications we can perform on anOEM EFIare somewhat limited because the OEM ECU isnot reprogrammable. However, there are a number of things we learned that we mechanical engineers do to modify the EFI system without having to reprogram the ECU. We can amplification the fuel pressureas this is one reading that the ECU of a normal efi kit used in the cult us eg does not take into account it assumes the fuel pressure is a constant 30 psi(an estimated value given by Pak Suzuki ) above intake manifold pressure we can discontinue the pulse signalform the ECU, alter it using input from the manifold pressure and send it to the injector we canincrease the injector nozzle size or increase the number of injectors. However, your best option, performance wise, is to install anaftermarket ECU. In the next few pages well discuss each of these options.Bottom of FormBottom of Form pass off of FormThere are a few important factors that our study shows that must be taken into account wheninstalling an efi engine. These are thepulse durationof the injectors and theduty cycle.The injector pulse duration is the amount of time that the injector is held open so that it can inject fuel into the combustion chamber. The pulse duration is controlled by the engine control unit (ECU) and is dependent on various sensors in the electronic fuel injection (EFI) sy stem. The longer the pulse duration, the more fuel is added to the air/fuel mixture. The amount of fuel required at any one time varies by the amount ofair flow, theair density, theengine load, and theengine temperature. Therefore the pulse duration will vary. However, there is only a limited amount of time that the injector can be held open at each revolution of the engine. This amount of time is reduced asengine speedincreases. For example, at 600 RPM the available time is 0.1 seconds (60 seconds in a minute divided by 600 revolutions) but at 6,000 RPM it is only 0.01 seconds. The pulse duration relative to the available time at the enginered lineis called the duty cycle and is verbalised as a percentage. Thus a duty cycle of 80% means that at the engine red line the pulse duration (the amount of time the injector is help open) is 80% of the available time.Top of FormINCREASING THE DUTY CYCLETop of FormINCREASING INJECTOR NOZZLE SIZETop of FormPerformance ECU ChipsTop of FormRepl acing thestock ECU chipwith areprogrammed performance chipis a good option for anything up to a 10% increase in engine power. This is mainly due to the way in which the stock ECU chip is programmed. In essence, the stock ECU is programmed for optimal performance atpeak torqueso as this ensures that the car is drivable at low engine speeds. As most cars would be driven at low engine speeds of up to 3,500 RPM, ensuring that the car drives perfectly at these engine speeds is perfectly reasonable unless you want to modify your car A reprogrammed performance chip will be programmed for optimal performance up to theengine red line, releasing a moderate power increase but making the car less drivable at lower engine speeds.Top of FormTHE FUEL PICKUPThe fuel pickup should also get some consideration, especially on a modified street race car with asteel fuel tank. On such vehicles the fuel level in the fuel tank can fall off below the fuel pickup duringhard corneringorheavy accelerationand heavy brakingand can cause a momentary drop in fuel pressure and engine performance. The solution is to have asecondary fuel pump summate a smallfuel reservoiror pass pot that feels the primary fuel pumps. The fuel reservoir is a simple cylinder with an fuel inlet from the secondary pump at the side, a fuel return line at the top and fuel pickup lines to the primary pumps at the bottom. The fuel reservoir should have a capacity of at least 1 liter and should be mounted low, beside the fuel tank. With a fuel reservoir, the primary fuel pumps will always have a fuel supply even under hard cornering of heavy acceleration and braking conditions.Calculation on this bases were done and were utilized in MATLAB programBottom of Form