[A305] Motor Konstrüksiyonu Ders Notu (Motor Elemanları Ve Çalışma Prensipleri)

Temel Motor Elemanları ve Çalışma Prensipleri

Başla

4 Stroklu İçten Yanmalı Motor

Bileşen?

Krank mili

Fonksiyonu Sonraki

4 Stroklu İçten Yanmalı Motor

Bileşen?

Piston Fonksiyonu Sonraki

4 Stroklu İçten Yanmalı Motor

Bileşen?

Egzoz Kanalı Fonksiyonu Sonraki

4 Stroklu İçten Yanmalı Motor Bileşen?

Kelebek Fonksiyonu

Sonraki

4 Stroklu İçten Yanmalı Motor

Bileşen?

Egzos Supabı Fonksiyonu

Sonraki

4 Stroklu İçten Yanmalı Motor Emme Supabı

Bileşen?

Fonksiyonu

Sonraki

4 Stroklu İçten Yanmalı Motor Su Ceketleri

Bileşen?

Fonksiyonu

Sonraki

4 Stroklu İçten Yanmalı Motor Bileşen?

Biyel

Fonksiyonu

Sonraki

4 Stroklu İçten Yanmalı Motor Zamanlama İşareti

Zamanlama İşareti

Fonksiyonu

Bileşen?

Sonraki

4 Stroklu İçten Yanmalı Motor Bu nedir?

Zamanlama İşareti

Fonksiyonu

Sonraki

4 Stroklu Motor İlk Devir Emme

Sıkıştırma

Bu nedir?

Hava/Yakıt Karışımı Fonksiyonu

Sonraki

4 Stroklu Motor İlk Devir Emme

Sıkıştırma Bu nedir?

Hava/Yakıt Sıkıştırma Fonksiyon

İleri

4 Stroklu Motor İkinci Devir Bu nedir?

Güç

Egzos

Hava/Yakıt Yanması

Fonksiyonu

İleri

4 Stroklu Motor İkinci Devir Güç

Egzos Bu nedir?

Egzos gazları Fonksiyonu

ileri

4 Stroklu Motor

KAM MİLİ KAM MİLİ Fonksiyonu

İleri

Motorlar Bileşen? Fonksiyonu

Külbütör KAM MİLİ KAM MİLİ

İleri

Motorlar Bileşent? İtici

KAM MİLİ

Fonksiyonu

KAM MİLİ

İleri

İlk Aşama – Normal Yanma

Bu nedir?

Ateşleme Fonksiyonu

İleri

First Stage – Normal Combustion Bu nedir?

Alev önü Fonksiyonu

İleri

İkinci Aşama – Normal Yanma Alevin yayılması

Bu nedir?

Fonksiyonu

İleri

Son aşama – Normal Yanma

Tam Yanma

Bu nedir?

Function

Uniform basınç pistonu aşağı iter

ileri

Abnormal Combustion Bu nedir? Sıcak karbon noktası

Fonksiyonu

Next

Abnormal Combustion What Is This?

Advanced Ignition Timing

Function

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Üstten Kamlı Motor

Fonksiyonu

ileri

Üstten Kamlı Motor Yağ

Fonksiyonu

Yüksek sürtünme nktalarına

ileri

Carburetor at Idle What Is This?

Idle Air/Fuel mixture Adjusting Screw Function

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ileri

Carburetor at Off Idle Venturi Area (Lower Pressure)

What Is This?

Function

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Feedback Carburetor Function

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Fuel Injector Function

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Throttle Body Fuel Injection

Function

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Multiport Fuel Injection Function

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Contact Point Distributor Ignition

Function

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Distributor Ignition System(DI)

Function

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Waste Spark Ignition System (EI)

Function

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Coil on Plug Ignition

Function

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Ignition Test Voltage required To get spark plug to fire

Function

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Ignition Test Voltage required To maintain spark Function

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Throttle Plate The throttle plate controls the amount of air allowed into the combustion chamber of the engine. This in turn controls the speed and power of the engine. The driver of the vehicle controls the throttle plate. This is done by depressing the accelerator pedal with their foot. By depressing the accelerator pedal the throttle plate is rotated to allow more air to enter the intake system and thus the amount of air allowed into the combustion chamber. Copyright©CIAT2009

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Krank Mili Pistonun aşağı- Yukarı hareketini kontrol eden Biyel Muyluları. Şekilde 4 Stroklu motorlarda kullanılan Krank Mili Görülmektedir. Mavi eksen, dönüş esnasında tek eksende yeralan krank ana muylularını göstermektedir.

Geri

Piston Piston tacı Üst Kompresyon segmanı Alt Kompresyon Segmanı

Şekilde Biyele bağlı bir piston görülmektedir. Biyel vasıtasıyla ayrıca krank miline de bağlanılacaktır.

Yağ kontrol kanalı Perno Piston eteği

segman

Biyel kolu

Yataklar Biyel büyük başı

Biyel cıvataları

Yanma odası içerisinde yanma gerçekleştiğinde, bunun sonucu olan kuvvet piston üst yüzeyine etki eder. Sonuç olarak Biyel aşağı doğru hareket ettirilir. Krank mili dönmeye başlar.

Geri

Egzos Kanalı • Egzos kanalı egzos gazlarının yanma odasından dışarı atılmasını sağlar. Bu durum egzos strokunda pistonun yukarı hareketinde gerçekleşir. Bu esnada egzos supabı da açılmış olmalıdır. Supap, motorun düzgün çalışması açısından doğru zamanda açılıp kapanabilmelidir.

Geri

Kelebek Görevi, yanma odasına giren hava miktarını kontrol etmektir. Kelebek açıldıkça daha fazla miktarda hava içeri alınır. Daha fazla hava ve Yakıt motor gücünü ve hızını arttırır. Sürücü motor hızını, hava kelebeğini kontrol ederek ayarlar. Bağlantı, gaz pedalına bağlı kablo ile sağlanır.

Kelebek

Kelebek Kontrolü

Geri

EGR Valve The EGR valve is used to help prevent the formation of NOx during the combustion process. The valve allows a measured amount of exhaust gases to enter the combustion chamber before the ignition of the air fuel mixture. This lowers the peak combustion temperature, preventing the formation of NOx. The EGR valve shown here is controlled by vacuum. This vacuum is controlled in various ways to allow the exhaust gases into the combustion process at the correct time and amount. Copyright©CIAT2009

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Egzos Supabı Yanma odasını egzost kanalına karşı kapatır. Supapların açılıp kapanmasını kam mili kontrol eder. 4 strok boyunca, egzost strokunda piston yükselmeye başlayana kadar egzost supabı kapalı konumda kalır. Bu esnada kam mili vasıtasıyla açılan supap yoluyla gazlar egzos kanalına doğru süpürülür. Sonrasında emme stroku başlar. Egzost supabı kapanarak emme supabı açılır. Uygun miktarda hava/yakıt karışımı yanma odasına sevk edilir. Bu esnada her iki supap da kapalıdır ve sıkıştırma süreci başlar.

Geri

Emme Supabı Emme strokunda açılır. Pistonun aşağı hareketi esnasında yanma odasındaki basınç düşer. Düşük basınç, hava/yakıt karışımını içeri alır. Piston en alt noktaya ulaştığında supap kapanır. Piston yukarı harekete başlarken silindir içi basınç da artmaya başlar. Yanma odasındaki sıcaklık da artar. Piston strokunun en üst noktasına yakın şekilde ateşleme sistemi devreye girer ve yakıt hava karışımı ateşlenir.

Geri

Soğutma Sistemi Soğutma amaçlı olarak silindir içinde bırakılmış kanallardır. Ayrıca silindir kafa konstrüksiyonunda da bulunurlar. Soğutucu akışkan bu ceketler ve radyatör boyunca pompalanarak, ısınan sıvının hava aracılığı ile radyatör kanatçıklarında soğutulması sağlanır

Geri

Biyel Krank miline

Piston ve Krank miline birbirine bağlar. Doğrusal hareketin dönel harekete çevrilmesinde ara yardımcı elemandır.

Pistona

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Kam mili zamanlaması Zamanlama İşaretleri

Kam milini krank miline göre ayarlamak son derece önemlidir. Hem kam mili dişlileri hem de blok yapıda bırakılmış olan işaretler mevcuttur ki bunlar uygunca denk getirilmelidirler. Krank mili dişlisi ayrıca ÜÖN (üst ölü nokta) işaretine de sahiptir. Bu ayarlarda üreticinin direktifleri önem taşır.

Geri

Supap Toleransı The clearance between the stem of the valve and the rocker arm contact point is very important. If this clearance is not adjusted properly it could cause an engine running problem as well as an engine noise and or an emissions problem. Some of these clearances are not adjustable and are controlled by hydraulics. In some cases there is a tolerance of up to .060in. The manufactures specifications should always be consulted with these issues of valve clearance and or adjustments.

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O2 Sensör Test

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Yavaş O2 Sensör .080 second Maximum to maximum

Too Slow For Modern-day Vehicle Maximum .060 second

Crossovers of .45V per second = 2 Minimum should = 3 Copyright©CIAT2009

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O2 Sensör Test 2

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Proper Functioning O2 Sensor .045 Second Maximum to Maximum

Crossovers of .45V per second = 4 Minimum should = 3 Copyright©CIAT2009

Satisfactory For Modern-day Vehicle Maximum .060 second

Air/Fuel Mixture As the piston moves downward within the cylinder, a low pressure is created. At this point the intake valve opens, allowing the air/fuel mixture to be forced into the low pressure area of the combustion chamber. The atmospheric pressure forces the air/fuel mixture into the low pressure area within the combustion chamber during the intake stroke. Copyright©CIAT2009

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Compressing Air/Fuel Mixture As the piston moves up, within the cylinder, the air/fuel mixture is compressed. This compression causes the temperature of the mixture to increase. As the piston reaches near its highest point, the temperature is near the combustion point. Next the ignition ignites the air/fuel mixture by creating an “arch” across the spark plug gap. Copyright©CIAT2009

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Heat and Pressure The combustion process produces high pressure and temperature to the top of the piston. As the piston is in its downward stroke, it produces a pressure on the crankshaft. This produces the torque that is used to propel the vehicle down the road. The greatest torque is produced at about 12 degrees past top dead center, during the power stroke. Copyright©CIAT2009

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Exhaust Gases As the piston moves up during the exhaust stroke, The exhaust valve must be open. The exhaust gases are what is left of the Air/Fuel mixture after the combustion process is completed. The ideal exhaust gases would consist of H2O vapor, CO2 and N2. However there is also some CO (carbon monoxide) HC (hydrocarbon) and Oxides on Nitrogen (NOx). Return Copyright©CIAT2009

Valve Spring The valve spring is used to properly seat the valve to prevent leakage. The seal is especially important during the compression and power stroke of the piston. If this spring is broken or is too week, it can cause drivability and or emissions problems. The proper seating can be check by conducting a cylinder leak down test. Copyright©CIAT2009

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Rocker Arm The rocker is used to open the valve at the proper time and allowing it to stay open for the proper length of time. In this case the rocker is controlled by a push rod which is controlled by the camshaft. Some rocker arms are adjusted to a specific clearance between the valve stem and the contact of the rocker arm. Copyright©CIAT2009

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Push Rod The push rod is used to control the opening and closing of the valve. The push rod is controlled by the cam shaft. As the rod is pushed up by the lob on the cam shaft, the push rod forces the rocker arm to open the valve into the combustion chamber. The push rod is used in engines where the camshaft is located in the block of the engine. Return Copyright©CIAT2009

Fuel Injector Doğru miktarda yakıtı , to create the correct air/fuel ratio for the current demands on engine speed and power. The injector is turned on/off by the onboard computer (PCM). The fuel is broken up into a fine spray pattern by the injector. This spray is then vaporized by the low pressure in the combustion chamber during the intake stroke. Malfunctions

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Fuel Injector Malfunction If the fuel injector should malfunction, it can cause driveabily as well as emissions problems. If the injector should not seat properly, it could cause a rich running condition (high CO). If the orifice should build up a carbon deposit, the spray pattern will be distorted and the results could be an incomplete vaporization of the fuel. This in turn could cause an incomplete combustion with a resulting high HC emission. Also, if the injector is not opening, it would cause a misfire. However, since there is no HC entering that combustion chamber, there would not be an increase in HC. Copyright©CIAT2009

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Ateşleme Zamanlaması Ateşleme zamanlama işareti uygun olarak ayarlandığında , 1 no’lu piston üst ölü noktadadır. Şekilde zamanlama zinciri muhafazasındaki işaret ile krank mili kasnağındaki işaret bir hizaya getirilmiştir. Genellikle bu çizgiler üst ölü noktadan çok az öndedirler.

Arızalar

Geri

Ignition Timing Malfunction If the ignition timing is too far advanced, It can cause a “pinging” problem within the engine. This can also produce an elevated amount of both HC and NOx exhaust gases. By igniting the air/fuel mixture too early in the compression stroke, the result will be a higher peak pressure and temperature within the cylinder. This can produce elevated HC and or NOx in the exhaust gases. Return Copyright©CIAT2009

Push Rod The push rod is the connection between the camshaft and the valve rocker arm. This push rod is used on the OHV (overhead valve) engine. In this case the camshaft is located within the engine block. The push rod is moved up and down as the camshaft lob comes in contact with it. This in turn opens and closes the corresponding valve, via the valve rocker arm. Return Copyright©CIAT2009

Ignition Spark Ignition spark is used to ignite the air/fuel mixture within the combustion chamber. This is done when the piston reaches a proper point in its upward stroke. This position of the piston is determined by engine speed and load. This is termed as ignition timing. This was controlled by vacuum and centrifugal weights within the distributor in the older vehicles with mechanical ignition distributors. In the modernday vehicle spark timing is controlled by the PCM. Return Copyright©CIAT2009

Initial Flame Front When the ignition spark ignites the air/fuel mixture, a flame front is created in an area surrounding the spark plug. If the conditions for proper “burning” of the air/fuel mixture is correct, the flame front proceeds across the combustion chamber. If the air/fuel mixture is rich, the flame front will proceed faster. If the air/fuel mixture is lean, the flame front will move slower. Copyright©CIAT2009

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Second Stage – Normal Combustion If the combustion process is functioning normally, the flame front will proceed across the combustion chamber. It should be noted that the piston is still in its upward movement. This produces a higher pressure within the combustion chamber. Also, the “burning” of the air fuel mixture creates more heat and pressure. Thus the upward movement of the piston and the burning of the air/fuel mixture is creating a very high pressure, during the compression stroke of the piston. Return Copyright©CIAT2009

Complete Combustion When the air/fuel mixture has burned to completion, The maximum pressure is produced within the combustion chamber. It should be noted the piston is in its downward movement at this point. The greatest torque produced on the crankshaft is when the piston is about 12 degrees past TDC. Now the piston will move to its bottom most position and then it will start moving up in the exhaust stroke. Copyright©CIAT2009

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Abnormal Combustion 1 At times an engine will “ping” or “knock” during acceleration. One cause for this condition is carbon buildup on top of the piston or within the combustion chamber. Carbon retains heat. So when the piston moves up during the compression stroke, the carbon “hot spot” can ignite the air/fuel mixture. This will produce a second flame front and when the two collide, the result will be a “ping” or “knock”. Copyright©CIAT2009

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Abnormal Combustion 2 If the ignition timing is advanced too far, the results can be a “pinging” during acceleration. This is caused by the high pressure during the compression stroke. The flame front is proceeding across the combustion chamber. Meanwhile, the pressure is increasing causing the temperature within the chamber to increase. The air/fuel mixture will ignite at another point and cause a second flame front to be created. When these two flame fronts collide, It causes aCopyright©CIAT2009 “ping”. Return

Overhead Cam The overhead cam engine has its camshaft located within the head. This eliminates the need for the pushrod which is used in the overhead valve engine. This type of valve function, at times, uses a rocker arm. However, some OHC systems control the opening and closing of the valves by directly positioning the valve stems next to the lobes of the camshaft. This eliminates the need for a rocker arm. Copyright©CIAT2009

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Overhead Cam Engine The camshaft on this type of engine is located on the top portion of the cylinder head. This eliminates the need for a “push rod” to control the opening and closing of the valves. Nearly all modern-day vehicles have this type of camshaft operation. If there is only one camshaft per head, there is still a need for the rocker arm to control the opening and closing of the valves. If the vehicle has two camshafts per head, there is no need for a rocker arm. In this case, the camshaft lobes are in direct contact with the valve stem. In this case, there are some valve adjustments done with shims. Copyright©CIAT2009 Return

Overhead Valve Engine Push Rod Cam Follower

The camshaft, in an overhead valve engine, is located in the engine block. This requires a “push rod” to control the opening and closing of the valves at the correct time. The push rods fit into a cam follower which is in constant contact with the camshaft. Some of these cam followers were hydraulic controlled. This eliminated and valve adjustments. However, some were not hydraulic and these needed the proper valve clearance. Again, this adjustment must be performed on a warm engine for the proper clearance to adjust to a normal operating engine temperature.

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Idle Air/Fuel Adjustment

Idle Air/Fuel mixture Adjustment Screw

The proper air/fuel mixture, entering the engine at idle rpm, can be adjusted. The engine must be at the proper rpm and normal operating temperature. The mixture screw is turned clockwise to restrict the flow of fuel. With the engine running at proper idle speed and at normal operating temperature, the mixture screw is turned clockwise until the rpm starts to go down. The screw is then turned counter clockwise ¼ turn. This should control the proper air/fuel mixture entering the engine at idle rpm.

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Carburetor Venturi Area Atmospheric Pressure

Low Pressure Area

The fuel is forced into the throat of the carburetor be the higher atmospheric pressure into the lower pressure within the carburetor. This lower pressure is created by the “venturi” within the throat of the carburetor. The venturi is like the shape of an airplane wing. In fact that is what causes an airplane to fly. As the air passes over the wing, a lower pressure is created on top of the wing. Thus the atmospheric pressure forces the wing up thus causing the plane to fly. The same thing happens within the venturi area of the carburetor. The more air that passes over the venturi, the lower the pressure. The result is more fuel is forced into the carburetor throat. Thus the mixture stays balanced and the engine runs faster with more power.

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Feedback Carburetor The feedback carburetor is controlled by the on-board computer (PCM). It does so by controlling the mixture control solenoid within the carburetor. It either allows or disallows the fuel to enter the main discharge nozzle or the idle circuit. This controls the air/fuel ratio under various operating conditions. The technician can monitor the controlling signal to the discharge nozzle solenoid. This signal should be 30 degrees dwell under ideal air/fuel ratio. If the dwell reading is higher, the PCM is leaning out a rich mixture. The opposite is true, if the dwell reading is lower than 30 degrees, the PCM is richening up a lean running condition. Copyright©CIAT2009

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Fuel Injector The illustration on the left is of a fuel injector. The electrical terminals is when the injector is electrically connected to the PCM. The PCM controls the “on time” of the injector by supplying an electrical ground to the injector solenoid coil. The “fuel in” shown in the illustration is where the fuel is supplied to the injector at a constant pressure. When the solenoid coil is energized, the injector opens and the fuel is injected into the intake system. Copyright©CIAT2009

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Throttle Body Fuel Injection This system of fuel injection is mounted on the intake manifold where the carburetor used to be. It should be noted the fuel pressure regulator controls the fuel pressure. Any fuel that is not required to maintain the correct fuel pressure is allowed to returned to the fuel tank. The idle speed is controlled by the PCM. It does so by controlling the amount of air allowed into the intake system below the throttle plate (idle air control valve). Return Copyright©CIAT2009

Multiport Fuel Injection The multiport fuel injection system has one injector for each cylinder. Each of these injectors are controlled by the PCM. Each injector is located in the intake manifold next to the intake valve for that cylinder. The fuel pressure is maintained at a specific level. Any gasoline that is not needed to maintain this pressure is returned to the gas tank. The fuel pump can be located in the tank or any where along the line to the engine. Return Copyright©CIAT2009

Contact Point Distributor Ignition This type of ignition system uses a distributor with contact points. As these points close they provide a complete circuit for the coil primary circuit. As these points open, the magnetic field created by the current flow through the primary windings, collapse. This creates a very high voltage in the secondary windings of the coil. This is the voltage that is used to “jump” the sparkplug gap which begins the combustion process within the combustion chamber. Copyright©CIAT2009

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Distributor Ignition System (DI) This ignition system uses a distributor that creates an electronic signal. This signal is sent to the “control unit”. This unit then opens and closes the coil primary circuit at the proper time. When the primary circuit is opened, the magnetic field created by the current flow through the primary windings, collapses and the high voltage is created in the secondary windings of the coil. This high voltage is directed to the cylinder sparkplug. This all happens at the correct time for the ignition of the air/fuel mixture within the combustion chamber. Copyright©CIAT2009

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Waste Spark Ignition System (EI) This ignition system fires two sparkplugs at the same time. The secondary wire is connected to the cylinders that are on the opposite stroke when the piston is in its upward stroke. One plug fires on the compression stroke while the other fires on the exhaust stroke. This is called a “waste spark” system, as when the coil fires, on sparkplug fires when there is no compression of air/fuel mixture to ignite. The opening and closing of the coil primary windings is controlled by the PCM. Copyright©CIAT2009

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Coil On Plug Ignition System (COP) This type of ignition system uses one coil per sparkplug. The secondary of the coil is connected directly to the sparkplug. This system eliminates the need for sparkplug wires. This also eliminates the magnetic fields created by the sparkplug wires. These fields can cause computer control problems as it creates “radio signals” which can interfere with the computer sensor signals needed to fine tune the proper running of the engine. This ignition system is Return Copyright©CIAT2009 controlled by the PCM.