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I G N IT I O N AN D ELECTRI CAL SYSTEMS
based o n throttle valve position and engine speed. This system i s comprised of 4-pulser coils, battery charging coil, condenser charge coil. There is also a gear counter coil to control ignition timing at all rpm, an ignition timing sensor that provides an automatic JCBTDC advance for engine starting. lt will remain at JCBTDC for 1 2-1 5 seconds, at which time the ignition timing will return to the idle speed circuit and whatever position the "Idle Speed Adjustment Switch" is set at.
** CAUTION Due to the higher idle speed created by this automatic starting device, DO NOT shift the engine until the engine rpm has returned to idle speed. Fuel Injected DT1 1 5 and DT140 The fuel injected models use the Suzuki Micro-Link ignition system. This system uses sensors to monitor specific engine operating conditions and sup plies signals to an Engine Control Unit (ECU) for ignition and warning opera tion. The primary ignition sensors are the throttle valve sensor (TVS) for determining throttle valve opening angle and the engine speed sensor (gear count coil) that determines engine speed. Based on these signals, the ECU determines the ignition timing necessary for the engine's current requirements and del ivers voltage to the ignition coils thus producing ignition spark. Two compensation sensors, cylinder wall temperature and air temperature, supply signals used by the ECU to compensate ignition timing based on tem perature related conditions. A pulser coil supplies crankshaft angle signals which the ECU uses when determining a trigger signal for the ignition. DURING START At engine start, the ignition timing is set at 5°BTDC Sequential operation while cranking (below 440 rpm). AFTER START After engine start, keeping the throttle lever at the idle position will allow the ECU "Warm-up mode" map to control the ignition timing in relation to cylinder wall temperature. In this mode, ignition timing stays advanced above normal until the cylinder wall temperature reaches 1 1 3° (45°C) the timer, which was set according to cylinder wall temperature, expires. NORMAL OPERATING MODE When the "Warm-up mode" ends, the ECU changes to the "Normal operating mode". This mode is based on the map control in relation to engine speed, throttle valve opening angle, cylinder wall temperature and air temperature. FAIL SAFE MODE Each sensor has an assigned default value programmed into the ECU. In the event of a sensor failure, the monitor gauge flash code will indicate the failure and the engine will continue to operate, but with much reduced performance, ignition timing during a sensor failure will automatically default to the following method of control : Throttle valve sensor failure: Ignition timing w i l l b e automatically set according to the engine speed. Cylinder wall temperature sensor failure: Ignition timing will be automati cally set as if the sensor senses 86°F (30°C). Air temperature sensor failure: Ignition timing wil l be automatically set as if the sensor senses 68°F (20°C). If either gear counter coil or pulser coil fails, the ECU will not provide and injection signal without a reference from these coils. Under this condition, the engine can be cranked, but it will not start due to no fuel injection pressure. •
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DT1 50, DT175, DT200 and DT225 These models are equipped with the Micro-Link ignition system. This system incorporates a microcomputer to improve engine performance by maximizing combustion control . This system uses information from sensors and switches located a various positions on the engine to monitor throttle valve opening, engine rpm, shift lever position and operator selected idle speed. The micro computer constantly evaluates this information and instantly provides the opti mal spark timing for the current engine running conditions. The Micro-Link system also monitors the caution system sensors for oil
level, oil flow, water flow and engine over-rev. If any of these sensors indicate a malfunction, the microcomputer wil l activate a warning buzzer and/or monitor gauge indicator lamp and then operate the engine under reduced power. The magneto consists of the following components. Each coil functions as follows: The condenser charging coil charges the condenser for the spark primary power source in the CDI unit. The pulser coils, positioned 1 20°apart. When the pulser coil voltage enters the delay circuit, the CDI unit begins to count the voltage signals from the gear counter coil and will release the signal from the delay circuit when the flywheel indicates the proper piston position according to the idle speed adjust ment switch setting. The counter coil causes a reference pulse to decide the ignition timing to be input into the microcomputer. The battery charging coils, No.1 and No.2, perform power generating nec essary to charge the battery. In addition, the microcomputer gets it's 1 2 volt operating power from the bat tery. •
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System Testing PROCEDURE Perform a visual inspection of the wiring connections and grounds. Deter mine if the problem affects all or just certain cylinders and perform a spark check using a spark gap tool ("spark tester") and then check ignition timing with a timing light. If the problem affects all the cylinders, check the capacitor charge coil out put, engine stop switch, COl unit output and pulse coil output. If the problem affects individual cylinders only, check the components whose failure would affect that particular cylinder such as the pulse coil and ignition coil performance. If the problem is timing related, check the mechanical part of the system, such as the pulse coil or CDI box itself and then check the electronic timing advance components of the system, the throttle position sensor (if applicable), the pulse coil(s) and the CDI module. CDI troubleshooting can be performed with a peak reading voltmeter. This will check the CDI voltage to the ignition coils. If CDI voltage is good, isolate individual ignition coils or spark plugs and check output voltage. If the COl voltage is bad, check all COl input voltages. Check the pulse coil output to the CDI unit. Check the capacitor charge coil output to the CDI unit. Check the pulser coil output to the COl unit. If all the input voltages are normal, the problem has now been isolated to the CDI unit itself. If any input voltage is abnormal, check the appropriate coil for winding resistance and insulation breakdown. If the problem is timing related, check all the timing inputs to the CDI unit, such as the throttle position sensor. If the timing inputs are good, the problem is isolated to the CDI unit. •
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Pulsar/Charging/Gear Counter Coils DESCRIPTION & OPERATION The second circuit used in CDI systems is the pulsar circuit. The pulsar cir cuit has its own flywheel magnet, a pulsar coil, a diode, and a thyristor. A thyristor is a solid state electronic switching device which permits voltage to flow only after it is triggered by another voltage source. At the point in time when the ignition timing marks align, an alternating cur rent is induced in the pulsar coil , in the same manner as previously described for the charge coil . This current is then passed to a second diode located in the CDI unit where it becomes DC current and flows on to the thyristor. This voltage triggers the thyristor to permit the voltage stored in the capacitor to be dis charged. The capacitor voltage passes through the thyristor and on to the pri mary windings of the ignition coil . In this manner, a spark a t the p l u g may b e accurately timed b y the timing marks on the flywheel relative to the magnets in the flywheel and to provide as many as 1 00 sparks per second for a powerhead operating at 6000 rpm. A system of battery charging is standard on all electric start model engines.