Isuzu KB P190. Manual — part 500

Section 6 Engine Diagnosis . . . . . . . . . . . . . . . . . . . . . . .. 2001

PAGE

Section 6A Engine Mechanical . . . . . . . . . . . . . . . . . . . . . 2015

Section 6B Engine Cooling . . . . . . . . . . . . . . . . . . . . . . .. 2105

Section 6C Fuel System . . . . . . . . . . . . . . . . . . . . . . . ... 2119

Section 6D Engine Electrical . . . . . . . . . . . . . . . . . . . . . ... 2137

Section 6E Engine Driveability and Emissions . . . . . . . . . . . . . . .. 2171

Section 6F Exhaust System . . . . . . . . . . . . . . . . . . . . . . 2450

SECTION 6

ENGINE

TABLE OF CONTENTS

C24SE MODEL

ENGINE (C24SE) 6

Section 6G Engine Lubrication. . . . . . . . . . . . . . . . . . . . . 2465

Section 6H Engine Speed Control System . . . . . . . . . . . . . . . . 2472

Section 6J Induction . . . . . . . . . . . . . . . . . . . . . . . . ... 2476

ENGINE DIAGNOSIS (C24SE) 6-1

SECTION 6

ENGINE DIAGNOSIS

TABLE OF CONTENTS

PAGE

Engine Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6- 2

Hard Starting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 2

Engine Compression Test Procedure . . . . . . . . . . . . . . . . . . . 6- 3

Rough Engine Idling or Engine Stalling. . . . . . . . . . . . . . . . . .. 6- 4

Rough Engine Running . . . . . . . . . . . . . . . . . . . . . . . . 6- 5

Hesitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6- 6

Engine Lacks Power. . . . . . . . . . . . . . . . . . . . . . . . . . 6- 7

Engine Noisy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6- 8

Abnormal Noise Due to Hydraulic Lash Adjustor . . . . . . . . . . . . . .. 6- 9

Troubleshooting Procedure. . . . . . . . . . . . . . . . . . . . . . . 6- 9

Abnormal Combustion . . . . . . . . . . . . . . . . . . . . . . . . . 6-11

Engine Oil Consumption Excessive. . . . . . . . . . . . . . . . . . . 6-12

Fuel Consumption Excessive . . . . . . . . . . . . . . . . . . . . . .. 6-13

Oil Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6-13

Engine Oil Pressure Check . . . . . . . . . . . . . . . . . . . . . . .. 6-13

Malfunction Indicator Lamp . . . . . . . . . . . . . . . . . . . . . . . 6-14

6-2 ENGINE DIAGNOSIS (C24SE)

Engine Diagnosis

Hard Starting

1.Starting Motor Does Not Turn Over

Trouble Shooting Procedure
Turn on headlights and starter switch.

Condition Possible

cause Correction

Headlights go out or dim
considerably

Battery run down or under
charged

Recharge or replace battery

Terminals poorly connected

Clean battery posts and terminals
and connect properly

Starting motor coil circuit shorted

Overhaul or replace

Starting motor defective

Overhaul or replace

2.Ignition Trouble - Starting Motor Turns Over But Engine Does Not Start

Spark Test

Disconnect a high tension cable from any spark plug.
Connect the spark plug tester (use commercially
available tool), crank the engine, and check if a spark is
generated in the spark plug tester. Before cranking the
engine, make sure that the spark plug tester is properly
grounded. To avoid electrical shock, do not touch the
high tension cable while the engine is running.

Condition Possible

cause Correction

Spark jumps across gap

Spark plug defective

Clean, adjust spark gap or replace

Spark plug wire in correct

Connect properly or replace

Ignition timing incorrect

Refer to Ignition System

Fuel not reaching fuel injector(s)
or engine

Refer to item 3 (Trouble in fuel
system)

Valve timing incorrect

Adjust

Engine lacks compression

Refer to item 4 (Engine lacks
compression)

No sparking takes place

Ignition coil disconnected or
broken

Connect properly or replace

Electronic Ignition System with
module

Replace

Poor connections in engine
harness

Correct

Engine Control Module cable
disconnected or defective

Correct or replace

ENGINE DIAGNOSIS (C24SE) 6-3

3.Trouble in Fuel System

Condition Possible

cause Correction

Starting motor turns over and
spark occurs but engine does not
start.

Fuel tank empty

Fill

Water in fuel system

Clean

Fuel filter clogged

Replace filter

Fuel pipe clogged

Clean or replace

Fuel pump defective

Replace

Fuel pump circuit open

Correct or replace

Evaporative Emission Control
system circuit clogged

Correct or replace

Multiport Fuel Injection System
faulty

Refer to "Electronic Fuel Injection"
section

4.Engine Lacks Compression

Condition Possible

cause Correction

Engine lacks compression

Spark plug loosely fitted or spark
plug gasket defective

Tighten to specified torque or
replace gasket

Spark plug wire incorrect

Connect properly or replace

Valve timing incorrect

Adjust

Cylinder head gasket defective

Replace gasket

Valve incorrectly seated

Lap valve

Valve stem seized

Replace valve and valve guide

Valve spring weakened

Replace

Cylinder or piston rings worn

Overhaul engine

Piston ring seized

Overhaul engine.

Engine Compression Test Procedure

1. Start and run the engine until the engine

reaches normal operating temperature.

2. Turn the engine off.

3. Remove all the spark plugs.

4. Remove ignition coil fuse (15A) and disable the

ignition system.

5. Remove the fuel pump relay from the relay and

fuse box.

6. Engage the starter and check that the cranking

speed is approximately 300 rpm.

7. Install cylinder compression gauge into spark

plug hole.

8. With the throttle valve opened fully, keep the

starter engaged until the compression gauge
needle reaches the maximum level. Note the
reading.

9. Repeat the test with each cylinder.

The pressure difference between the individual
cylinders should not exceed 100kPa (14.5 psi).