Hyundai Coupe, Sedan Repair Manual 1994-1998

• Hyundai Accent
• Hyundai Elantra
• Hyundai Excel
• Hyundai Scoupe
• Hyundai Sonata
• Hyundai Tiburon

(See figures 22 and 23)

1. Disconnect the power transistor electrical connector.
   
   
2. Check for continuity at the cylinders' No. 1 and No. 4 power transistor.
   
   a) Connect the negative terminal of a 1.5 volt power supply (battery) to terminal 3 of the power transistor.
   
   b) Connect the positive terminal of a 1.5 volt power supply to terminal 4 of the power transistor.
   
   c) Connect the ohmmeter across terminals 3 and 5 (with the negative ohmmeter lead on terminal 5) of the power transistor connector.
   
   d) With 1.5 volts applied there should be continuity between terminals 3 and 5 of the power transistor connector.
   
   
3. Check for continuity at the cylinders' No. 2 and No. 3 power transistor.
   
   a) Connect the negative terminal of a 1.5 volt power supply (battery) to terminal 3 of the power transistor.
   
   b) Connect the positive terminal of a 1.5 volt power supply to terminal 2 of the power transistor.
   
   c) Connect the ohmmeter across terminals 1 and 3 (with the negative ohmmeter lead on terminal 1) of the power transistor connector.
   
   d) With 1.5 volts applied there should be continuity between terminals 1 and 3 of the power transistor connector.
   
   
4. Disconnect the 1.5 volt power supply from the power transistor connector.
5. Check for continuity again. Continuity should not exist.
6. If the power transistor does not respond as stated, it should be replaced.

REMOVAL AND INSTALLATION:

1. Disconnect the negative battery cable.
2. Disconnect the power transistor electrical harness.
3. Remove the power transistor mounting bolts.
4. Carefully remove the power transistor from the engine.
   
   TO INSTALL:
   
   
5. Install the power transistor on the engine.
6. Install the mounting bolt and tighten it securely.
7. Connect the power transistor electrical harness.
8. Connect the negative battery cable.

When there is a problem starting or driving a vehicle, two of the most important checks involve the ignition and the fuel systems. The question most mechanics attempt to answer first "is there a spark?" and "Is there fuel?" will often lead to solving most basic problems. For ignition system diagnosis and testing, please refer to the information on engine electrical components and ignition systems found earlier in this manual. If the ignition system checks out (there is spark), then you must determine if the fuel system is operating properly (is there fuel?).

GASOLINE FUEL INJECTION SYSTEM: GENERAL INFORMATION

The fuel injection system used on Hyundai vehicles is classified as a Multi-port Fuel Injection (MFI) system. The basic function of the system is to control the air/fuel ratio, based on input signals from various engine sensors. The air/fuel ratio is controlled by varying the injector drive time (pulse width). The system is controlled by an Electronic Control Module (ECM), which monitors the engines conditions, then calculates the injection timing and air/fuel ratio according to the signals from the sensors. The ECM consists of a microprocessor, Random Access Memory (RAM) Read Only Memory (ROM) and input and output signal interface systems.

The MFI system consists of 2 operating modes: Open Loop- air/fuel ratio is controlled by information programmed into the ECM by the manufacturer. Closed Loop- air/fuel ratio is varied by the ECM based on information supplied by the oxygen sensor.

An electrical fuel pump supplies sufficient fuel to the injection system and the pressure regulator maintains a constant pressure to the injectors. These injectors inject a metered quantity of fuel into the intake manifold in accordance with signals from the Electronic Control Module (ECM) or engine computer. After pressure regulation, excess fuel is returned to the fuel tank.

The injectors have two modes (injector Drive Timing) of operation: Non-synchronous Injection (Simultaneous injection) Synchronous Injection (Sequential Injection)

Non-synchronous Injection is activated during engine starting (cranking). There are 2 fuel injections, for each engine rpm, to all 4 cylinders. Also, during acceleration, fuel proportionate to the magnitude of acceleration, is injected to 2 selected cylinders during the intake and exhaust strokes.

Synchronous Injection is activated after the engine has started. The injectors are activated at the exhaust stroke of each cylinder in a sequential manner, according to the crankshaft angle sensor signal. There is 1 injector per cylinder for every 2 crankshaft revolutions, according to fire order.

• Tune-up and routine maintenance
• Engine and overhaul procedures
• Cooling, heating and air-conditioning systems
• Fuel and exhaust systems
• Engine electrical systems
• Emissions control systems
• Transmission
• Brakes
• Suspension and steering systems
• Body
• Chassis electrical system
• Wiring diagrams