engine is a double over head camshaft with hydraulic
lash adjusters and four valve per cylinder design.
The engine is free-wheeling; meaning it has provi-
sions for piston-to-valve clearance. However valve-to-
valve interference can occur, if camshafts are rotated
independently.

The cylinders are numbered from front of the

engine to the rear. The firing order is 1–3–4–2.

The engine identification number is located on the

rear of the cylinder block (Fig. 1).

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - ENGINE
DIAGNOSIS - INTRODUCTION

Engine diagnosis is helpful in determining the

causes of malfunctions not detected and remedied by
routine maintenance.

These malfunctions may be classified as either

mechanical (e.g., a strange noise), or performance
(e.g., engine idles rough and stalls).

Refer to the Engine Mechanical and the Engine

Performance diagnostic charts, for possible causes
and corrections of malfunctions (Refer to 9 - ENGINE
- DIAGNOSIS AND TESTING - MECHANICAL)
(Refer to 9 - ENGINE - DIAGNOSIS AND TESTING
- PERFORMANCE).

For fuel system diagnosis, (Refer to 14 - FUEL

SYSTEM/FUEL DELIVERY

DIAGNOSIS AND

TESTING).

Additional tests and diagnostic procedures may be

necessary for specific engine malfunctions that can-
not be isolated with the Service Diagnosis charts.
Information concerning additional tests and diagno-
sis is provided within the following:

• Cylinder Compression Pressure Test

• Cylinder Combustion Pressure Leakage Test

• Engine Cylinder Head Gasket Failure Diagnosis

• Intake Manifold Leakage Diagnosis

• Hydraulic Lash Adjuster Noise Diagnosis

• Engine Oil Leak Inspection

Fig. 1 Engine Identification

1 - ENGINE IDENTIFICATION LOCATION

ENGINE 2.4L

9 - 3

DIAGNOSIS AND TESTING - ENGINE DIAGNOSIS - PERFORMANCE

CONDITION

POSSIBLE CAUSE

CORRECTION

ENGINE WILL NOT START

1. Weak battery.

1. Test battery. Charge or replace
as necessary. (Refer to 8 -
ELECTRICAL/BATTERY SYSTEM -
DIAGNOSIS AND TESTING)

2. Corroded or loose battery
connections.

2. Clean and tighten battery
connections. Apply a coat of light
mineral grease to terminals.

3. Faulty starter.

3. Test starting system. (Refer to 8 -
ELECTRICAL/STARTING -
DIAGNOSIS AND TESTING)

4. Faulty coil(s) or control unit.

4. Test and replace as needed.
(Refer to Appropriate Diagnostic
Information)

5. Incorrect spark plug gap.

5. Set gap. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL
- SPECIFICATIONS)

6. Contamination in fuel system.

6. Clean system and replace fuel
filter.

7. Faulty fuel pump.

7. Test fuel pump and replace as
needed. (Refer to Appropriate
Diagnostic Information)

8. Incorrect engine timing.

8. Check for a skipped timing
belt/chain.

ENGINE STALLS OR IDLES
ROUGH

1. Idle speed too low.

1. Test minimum air flow. (Refer to
Appropriate Diagnostic Information)

2. Incorrect fuel mixture.

2. (Refer to Appropriate Diagnostic
Information)

3. Intake manifold leakage.

3. Inspect intake manifold, manifold
gasket, and vacuum hoses.

4. Faulty ignition coil(s).

4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

9 - 4

ENGINE 2.4L

ENGINE 2.4L (Continued)

CONDITION

POSSIBLE CAUSE

CORRECTION

ENGINE LOSS OF POWER

1. Dirty or incorrectly gapped plugs.

1. Clean plugs and set gap.

2. Contamination in fuel system.

2. Clean system and replace fuel
filter.

3. Faulty fuel pump.

3. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

4. Incorrect valve timing.

4. Correct valve timing.

5. Leaking cylinder head gasket.

5. Replace cylinder head gasket.

6. Low compression.

6. Test compression of each
cylinder.

7. Burned, warped, or pitted valves.

7. Replace valves.

8. Plugged or restricted exhaust
system.

8. Perform exhaust restriction test.
(Refer to 11 - EXHAUST SYSTEM -
DIAGNOSIS AND TESTING) Install
new parts, as necessary.

9. Faulty ignition coil(s).

9. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

ENGINE MISSES ON
ACCELERATION

1. Dirty or incorrectly gapped spark
plugs.

1. Clean spark plugs and set gap.

2. Contamination in Fuel System.

2. Clean fuel system and replace
fuel filter.

3. Burned, warped, or pitted valves.

3. Replace valves.

4. Faulty ignition coil(s).

4. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

ENGINE MISSES AT HIGH SPEED

1. Dirty or incorrect spark plug gap.

1. Clean spark plugs and set gap.

2. Faulty ignition coil(s).

2. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

3. Dirty fuel injector(s).

3. Test and replace as necessary.
(Refer to Appropriate Diagnostic
Information)

4. Contamination in fuel system.

4. Clean system and replace fuel
filter.

ENGINE 2.4L

9 - 5

ENGINE 2.4L (Continued)

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