Engine Controls - Basic Testing Hyundai Elantra I

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning computerized system, perform each test listed in this article.

Note. Perform all voltage tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions.

ENGINE COMPRESSION

Exhaust System Backpressure

Exhaust system can be checked with a vacuum or pressure gauge. If using a pressure gauge, remove O2 sensor or air injection check valve (if equipped). Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi, exhaust system or catalytic converter is plugged.

If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum slowly drops after stabilizing, check exhaust system for restrictions.

FUEL SYSTEM

FUEL PRESSURE RELEASE

Disconnect fuel pump harness connector at fuel tank rear side (under rear seat on Elantra). Start engine. After engine stalls, turn ignition switch to OFF position. Disconnect negative battery cable. Reconnect fuel pump harness connector.

FUEL PUMP TEST

Turn ignition switch to OFF position. Apply battery voltage to fuel pump drive terminal (Yellow wire on Elantra, Excel and Scoupe; Black/White wire on Sonata). (Scheme 1)- (Scheme 4). Remove fuel tank cap and listen for fuel pump operation. Pinch fuel hoses by hand and ensure fuel pressure can be felt.

Scheme 1

Scheme 2

Scheme 3

Scheme 4

Scheme 5

1. Release fuel pressure. See FUEL PRESSURE RELEASE. Disconnect high pressure fuel hose from top of fuel filter. Cover hose connection using rags to avoid spraying of fuel.
2. Using Fuel Pressure Gauge Adapter (09353-24200 ), install fuel pressure gauge to fuel filter. (Scheme 5) Tighten bolt to 18-25 ft. lbs. (25-34 N.m). Reinstall negative battery cable.
3. Start engine. Ensure no fuel leakage exists at pressure gauge or connection. Disconnect vacuum hose from fuel pressure regulator, and plug hose end.
4. Measure and record fuel pressure at idle. Reconnect vacuum hose, and again measure and record fuel pressure. See FUEL PUMP SPECIFICATIONS table. If measurements are not within specification, go to next step. If measurements are okay, go to step 8). FUEL PUMP SPECIFICATIONS Engine Application Pressure psi (kg/cm 2 ) Volume In One Min. Pts. (L) With Vacuum 39 (2.8) (1) Without Vacuum 46-49 (3.3-3.5) (1) (1) Information is not available from manufacturer.
5. If fuel pressure is low, check for: Restricted fuel filter. Fuel leaking to return side. This can be caused by poor seating of valve in fuel pressure regulator. Low fuel pump discharge pressure.
6. If fuel pressure is too high, check for: Sticking valve in fuel pressure regulator. Restricted or bent fuel return hose or pipe.
7. If fuel pressure does not differ whether vacuum hose is connected or not, check for: Restricted/damaged vacuum hose or fitting. Sticking or poor seating valve in fuel pressure regulator.
8. If measurements are okay in step 4), stop engine and ensure fuel pressure gauge reading does not drop. If fuel pressure drops slowly after engine is stopped, an injector is leaking. If fuel pressure drops immediately after engine is stopped, check valve inside fuel pump is not closed.
9. After testing is completed, release fuel pressure. See FUEL PRESSURE RELEASE. Disconnect fuel pressure gauge from adapter bolt. Ensure hose connection is covered by a shop towel to prevent fuel spray. Remove adapter bolt and replace with original bolt. Apply battery voltage to fuel pump drive terminal. (Scheme 1)- (Scheme 4). Check for leaks.

CONTROL RELAY TEST

1.5L

1. Remove control relay, located under left side of dashboard, near instrument panel. Using an ohmmeter, check continuity between terminals No. 3 and 8 and then terminals No. 2 and 8. (Scheme 6) Resistance should be about 95 ohms. Check continuity between terminals No. 6 and 7. Resistance should be about 35 ohms. Check continuity between relay terminals No. 1 and 4. Continuity should not exist. If continuity exists, control relay is defective. Replace control relay. If continuity does not exist, go to next step.
2. Connect 12-volt battery across relay terminals No. 6 (positive) and No. 7 (negative). Continuity should exist between terminals No. 1 and 4. Disconnect battery from relay. Using an ohmmeter, check continuity between terminals No. 1 and 3. Continuity should not exist. Check continuity between terminals No. 7 and 5, and then reverse leads.
3. Continuity should exist in one direction only. Connect 12-volt battery across terminals No. 5 and 7, and check continuity between terminals No. 1 and 3. Continuity should exist between terminals No. 1 and 3. If results are not satisfactory, replace control relay.

Scheme 6

1.6L, 2.0L & 3.0L

1. Remove control relay, located under right side of dashboard, near blower motor housing. Apply battery voltage across terminals No. 6 (positive) and No. 8 (negative) while checking voltage on terminals No. 1 and 2. (Scheme 7) If battery voltage exists, relay is okay. If battery voltage does not exist, replace relay.
2. Apply battery voltage across terminals No. 7 (positive) and No. 10 (negative) while checking continuity between terminals No. 3 and 4. If continuity exists, relay is okay. If continuity does not exist, replace relay.
3. Apply battery voltage across terminals No. 3 (positive) and No. 9 (negative) while checking continuity between terminals No. 3 and 4. If continuity exists, relay is okay. If continuity does not exist, replace relay.

Scheme 7

Spark (Spark Plug)

Connect spark plug to a high tension cable. Ground outer electrode (main body of spark plug), and crank engine. Spark should occur in discharge gap between electrodes. Spark plug gap should be .039-.043" (1.0-1.1 mm).

Ignition Coil Power Source

Disconnect coil primary connector. Turn ignition on. Using voltmeter, check voltage between positive terminal and ground. Battery voltage should exist.

Ignition Coil Resistance

1. Using an ohmmeter, measure primary coil resistance for cylinders No. 1 and 4 between coil connector terminals No. 1 and 3 (Elantra) or terminals No. 2 and 4 (Sonata 2.0L). Measure resistance for cylinders No. 2 and 3 between connector terminals No. 2 and 3 (Elantra) or No. 1 and 4 (Sonata 2.0L). (Scheme 8) See DIS IGNITION COIL RESISTANCE table.
2. To measure secondary coil resistance, disconnect ignition coil connector. Measure resistance between coil towers No. 1 and 4 and between coil towers No. 2 and 3. See DIS IGNITION COIL RESISTANCE table. Replace coil if readings are not within specification.

DIS IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C)

Scheme 8

Power Transistor

1. Disconnect connector from power transistor. To check power transistor for cylinders No. 1 and 4, apply 1.5 volts between power transistor terminals No. 3 (negative) and 4 (positive). (Scheme 9)or (Scheme 10).
2. Using analog ohmmeter, check continuity between terminals No. 3 and 5. With voltage applied to terminal No. 4, continuity should exist. With voltage removed from terminal No. 4, continuity should not exist.
3. To check power transistor for cylinders No. 2 and 3, apply 1.5 volts between power transistor terminals No. 2 (positive) and 3 (negative). Using analog voltmeter, check for continuity between terminals No. 1 and 3. With voltage applied to terminal No. 2, continuity should exist. With voltage removed from terminal No. 2, continuity should not exist.

Scheme 9

Scheme 10

Spark (Coil)

Check for spark at coil wire. Hold wire about 1/4" from an engine ground, and crank engine. If spark is produced, coil is okay. If spark is not produced, use a voltmeter to check voltage at negative side of coil (tach signal) while cranking engine. If voltage does not exist, see IGNITION COIL POWER SOURCE. If voltage does not fluctuate, check coil wiring, power transistor, ECU and distributor assembly. If voltage fluctuates, check coil resistance, coil wire and connections.

Connect spark plug to a high tension cable. Ground outer electrode (main body of spark plug) and crank engine. Spark should occur in discharge gap between electrodes. Spark plug gap should be .039-.043" (1.0-1.1 mm).

Disconnect coil primary connector. Turn ignition on. Using voltmeter, check voltage between positive terminal and ground. Battery voltage should exist.

1. Remove primary and secondary leads from ignition coil. Using an ohmmeter, check primary resistance between positive and negative terminals of coil. See EIS IGNITION COIL RESISTANCE table.
2. Check secondary resistance between ignition coil positive terminal and ignition coil tower. See EIS IGNITION COIL RESISTANCE table. Replace coil if readings are not within specification.

EIS IGNITION COIL RESISTANCE - Ohms @ 68°F (20°C)

Power Transistor (Excel & Scoupe)

1. Disconnect connector from power transistor. Apply 3.0 volts between power transistor terminals No. 2 (negative) and 3 (positive). (Scheme 9)
2. Check continuity between terminals No. 1 and 2. With voltage applied to terminal No. 3, continuity should exist. With voltage removed from terminal No. 3, continuity should not exist. If continuity is not as specified, power transistor is defective.

Power Transistor (Sonata 3.0L)

1. Disconnect connector from power transistor. Apply 3.0 volts between power transistor terminals No. 1 (positive) and 2 (negative). (Scheme 9)or (Scheme 10).
2. Check continuity between terminals No. 2 and 3. With voltage applied to terminal No. 1, continuity should exist. With voltage removed from terminal No. 1, continuity should not exist. If continuity is not as specified, power transistor is defective.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS article in the ENGINE PERFORMANCE Section.

SUMMARY

If no faults were found while performing BASIC TESTING , proceed to TESTS W/CODES article in the ENGINE PERFORMANCE Section. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.