Engine Controls - Basic Testing Hyundai Sonata II

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's 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 the computerized system, perform each test listed in this article.

Note. Perform all voltage tests with 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 to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Compression

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

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or 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 a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL PRESSURE RELEASE

Disconnect fuel pump harness connector at fuel tank rear side. 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 connector (on Excel, Yellow wire, all others White/Black wire). (Scheme 1)or (Scheme 2). 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

1. Release fuel pressure. See FUEL PRESSURE RELEASE in this article. Disconnect high pressure fuel hose from to delivery pipe (at fuel filter). (Scheme 3) Cover hose connection with rags to avoid spraying of fuel.
2. Using the Fuel Pressure Gauge Adapter (09353-24200), install the fuel pressure gauge to the fuel filter. (Scheme 3) Tighten bolt to 18-25 ft. lbs. (25-34 N.m). Reinstall the negative battery cable.
3. Start engine. Ensure no fuel leakage is present from the pressure gauge or connection. Disconnect vacuum hose from fuel pressure regulator and plug the hose end.
4. Measure and record fuel pressure at idle. Reconnect vacuum hose and again measure and record fuel pressure. For fuel pressure specifications, see FUEL PUMP SPECIFICATIONS table. If measurements are not within specification, go to step 5). If measurements are okay, go to step 8). FUEL PUMP SPECIFICATIONS Application Pressure psi (kg/cm 2 ) (1) Excel & Sonata 2.4L With Vacuum 39 (2.8) Without Vacuum 47-50 (3.3-3.5) Sonata 3.0L With Vacuum 38 (2.7) Without Vacuum 46-49 (3.2-3.4) (1) Fuel pump volume specification is not available from manufacturer.
5. If fuel pressure is low, check the following items: Restricted fuel filter. Fuel leaking to the return side. This can be caused by poor seating of the valve in the fuel pressure regulator. Low fuel pump discharge pressure.
6. If fuel pressure is too high, check the following items: Sticking valve in fuel pressure regulator. Restricted or bent fuel return hose or pipe.
7. If there is no difference in fuel pressure whether vacuum hose is connected or not, check the following: Restricted/damaged vacuum hose or fitting. Sticking or poor seating valve in fuel pressure regulator.
8. 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 in this article. Disconnect the fuel pressure gauge from the adapter bolt. Ensure the hose connection is covered with 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)and (Scheme 2). Check for leaks.

Control Relay (1.5L & 2.4L)

1. Disconnect control relay connector. Using an ohmmeter, check continuity between relay terminals No. 1 and 4. (Scheme 4) If no continuity is present, go to next step. If continuity is present, control relay is defective. Replace control relay.
2. Check resistance between terminals No. 3 and 8, and terminals No. 2 and 8. Approximately 95 ohms resistance should be present. If resistance is not within specification, replace control relay.
3. Check resistance between terminals No. 6 and 7. Approximately 35 ohms resistance should be present.
4. Check continuity between terminals No. 5 and 7, then reverse leads. Continuity should exist in one direction only. If continuity exists in both or neither direction, control relay is defective.
5. Apply battery voltage across terminals No. 6 (positive) and No. 7 (negative), while checking continuity between terminals No. 1 and 4. If continuity is present, control relay is okay. If continuity does not exist, replace control relay.
6. Apply battery voltage across terminals No. 5 (positive) and No. 7 (negative), while checking continuity between terminals No. 1 and 2. If continuity is present, relay is okay. If continuity is not present, replace control relay.

Scheme 4

Control Relay 3.0L

1. Disconnect electrical connector. Using an ohmmeter, check continuity between relay terminals No. 3 and 4, and terminals No. 1 and 6. (Scheme 5) If continuity is not present, go to next step. If continuity is present, control relay is defective.
2. Check resistance between terminals No. 3 and 9. Approximately 95 ohms resistance should be present. Check resistance between terminals No. 7 and 10. Approximately 35 ohms resistance should be present. Check continuity between terminals No. 6 and 8, then reverse leads. Continuity should exist in one direction only. If continuity is not as specified, control relay is defective.
3. Apply battery voltage across terminals No. 7 (positive) and No. 10 (negative), while checking continuity between terminals No. 3 and 4. If continuity is present, control relay is okay. If continuity is not present, replace control relay.
4. Apply battery voltage across terminals No. 6 (positive) and No. 8 (negative), while checking voltage on terminals No. 1 and 2. If battery voltage is present, control relay is okay. If battery voltage is not present on terminals No. 1 and 2, replace control relay.

Scheme 5

Spark (Coil)

Check for spark at coil wire. Hold wire approximately 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 is not present, 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.

Spark (Spark Plug)

Connect spark plug to a high tension cable. Ground outer electrode (main body of spark plug) and crank engine. If good, 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.

Power Transistor

1. Remove connector from power transistor. Apply 1.5 volts (3 volts on Sonata 2.4L) between power transistor terminals No. 1 and 2. (Scheme 6)& (Scheme 7).
2. Check continuity between terminals No. 2 and 3 with terminal No. 1 disconnected from battery, no continuity should be present. With terminal No. 1 connected to battery, there should be continuity between terminals No. 2 and 3.

Scheme 6

Scheme 7

Ignition Coil Resistance

1. Remove primary and secondary leads from ignition coil. Using an ohmmeter, check primary resistance between positive and negative terminals of coil. Resistance should be .72-.88 ohm.
2. Check secondary resistance between ignition coil positive terminal and high voltage terminal. Resistance should be 10,300-13,900 ohms. Replace coil if readings are not within specifications.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ON-VEHICLE ADJUSTMENTS article.

IGNITION TIMING (Degrees BTDC @ RPM)

SUMMARY

If no faults were found while performing BASIC TESTING , proceed to TESTS W/CODES article. If no hard codes are found in self-diagnostics, or vehicle does not have a self-diagnostic system, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.