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35 - E THEORY/OPERATION Article Text 1989 Volkswagen Golf...

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E - THEORY/OPERATION Article Text 1989 Volkswagen Golf For Volkswagen Technical Site Copyright © 1998 Mitchell Repair Information Company, LLC Monday, August 23, 1999 11:48PM ARTICLE BEGINNING 1989 ENGINE PERFORMANCE Volkswagen Theory & Operation - CIS-E Fox, Golf, Golf GT, Jetta INTRODUCTION This article covers the basic description and operation of engine performance related systems and components. Prior to diagnosing vehicles or systems with which you are not completely familiar, read through this article. Bosch CIS-E fuel injection system uses Continuous Injection System (CIS) for fuel delivery and electronic controls for mixture adjustment. Mechanical portion of CIS-E system consists of Mixture Control Unit (MCU) which is also known as the fuel distributor, airflow sensor plate, diaphragm pressure regulator, fuel injectors, fuel pumps and filter. Electronic controls consist of airflow sensor position indicator (potentiometer), Differential Pressure Regulator (DPR), thermo time switch, coolant temperature sensor, Electronic Control Unit (ECU), oxygen sensor, auxiliary air regulator, idle speed stabilizer control unit, cold start valve, idle speed boost valve. COMPUTERIZED ENGINE CONTROLS CONTROL UNIT NOTE: For ease of understanding, components are grouped into 2 categories. The first category, INPUT DEVICES, is components which control or produce voltage signals that are monitored by the ECU. The second category, OUTPUT SIGNALS, are components that are controlled by the ECU (this is usually accomplished by the ECU grounding individual circuits). Electronic Control Unit (ECU) ECU is found behind plenum panel on driver's side of vehicle. ECU must not be exposed to temperatures above 180øF (85øC). ECU unit utilizes various input signals to control fuel delivery. Idle Speed Stabilizer Control Unit This unit is located near the fuse relay panel. Idle speed stabilizer control unit receives signals from ignition coil tach signal. When engine speed drops below 750 RPM, idle speed stabilizer control unit energizes the auxiliary air regulator to raise engine speed. INPUT DEVICES
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E - THEORY/OPERATION Article Text (p. 2) 1989 Volkswagen Golf For Volkswagen Technical Site Copyright © 1998 Mitchell Repair Information Company, LLC Monday, August 23, 1999 11:48PM All vehicles are equipped with different combinations of input devices. Not all devices are used on all models. To determine the input usage on a specific model, see L - WIRING DIAGRAMS article.
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