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Isuzu engine C22NE / 22LE / 20LE. Manual - part 64

DRIVEABILITY AND EMISSIONS 6E1-85

Surges and/or Chuggles Symptom (Cont'd)

Step

Action

Value(s)

Yes

Visually/Physically inspect the secondary ignition wires.

Check for the following conditions.
• Verify that all ignition wire resistance are less than the

specified value.

• Verify that ignition wires are correctly routed to eliminate

cross-firing.

• Verify that ignition wires are not arcing to ground.
Spraying the secondary ignition wires with a light mist of

water may help locate an intermittent problem.

Was a problem found?

#1 cyl. 4.7k

Ω

#2 cyl. 3.9k

Ω

#3 cyl. 3.4k

Ω

#4 cyl. 3.1k

Ω

Verify repair

Go to Step 13

1. Check ignition coil secondary resistance.

2. Replace the coil if it is greater than the specified

resistance.

Did the coil require replacement?

2.5 k

Ω

Verify repair

Go to Step 14

1. Remove the spark plugs and check for gas or oil

fouling cracks, wear, improper gap, burned electrodes,

heavy deposits or improper heat range.

2. If spark plugs are fouled, the cause of fouling must be

determined before replacing the spark plugs.

Was a problem found?

Verify repair

Go to Step 15

1. Check the injector connectors.

2. If any of the connectors are connected at an improper

cylinder, correct as necessary.

Was a problem found?

Verify repair

Go to Step 16

Check the ECM grounds to verify that they are clean and

tight. Refer to the ECM wiring diagrams in Electrical

Diagnosis.

Was a problem found?

Verify repair

Go to Step 17

Visually/Physically check the vacuum hoses for splits,

kinks and proper connections and proper connections and

routing as shown on the "Emission Control System

Schematics".

Was a problem found?

Verify repair

Go to Step 18

Check the exhaust system for a possible restriction:
• Damaged or collapsed pipes
• Internal muffler failure

Verify repair

Go to Step 19

1. Review all the diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:
• Visual/physical inspection.
• Scan Tool data.
• All electrical connections within a suspected circuit

and/or system.

Was a problem found?

Verify repair

Contact

Technical

Assistance

6E1-86 DRIVEABILITY AND EMISSIONS

Lack of Power, Sluggish or Spongy Symptom

Step

Action

Value(s)

Yes

DEFINITION: Engine delivers less than expected power. Little or no increase in speed when accelerator pedal is

pushed down part-way.

Was the On-Board Diagnostic (OBD) System Check

performed?

Go to Step 2

Go to OBD

System

Check

1. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

Verify Repair

Go to Step 3

Was a visual/physical check performed?

Go to Step 4

Go to

Visual/Physic

al Check

1. Remove and check the air filter element for dirt or

restrictions. Refer to Air Intake System in On-Vehicle

Service.

2. Replace the air filter element if necessary.

Was a repair required?

Verify repair

Go to Step 5

Check for proper ignition voltage output with the spark

tester (Use commercially available tool).

Was a problem found?

Verify repair

Go to Step 6

1. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned electrodes,

heavy deposits or improper heat range.

2. If spark plugs are fouled, the cause of fouling must be

determined before replacing the spark plugs.

Was a problem found?

Verify repair

Go to Step 7

Check the fuel pressure. Refer to Fuel System Pressure

Test.

Was a problem found?

Verify repair

Go to Step 8

Check for water or alcohol contaminated fuel.

Was a problem found?

Verify repair

Go to Step 9

Check the ECM grounds to verify that they are clean and

tight. Refer to the ECM wiring diagrams in Electrical

Diagnosis.

Was a problem found?

Verify repair

Go to Step 10

Check the exhaust system for a possible restriction:
• Damaged or collapsed pipes
• Internal muffler failure
Was a problem found?

Verify repair

Go to Step 10

DRIVEABILITY AND EMISSIONS 6E1-87

Lack of Power, Sluggish or Spongy Symptom (Cont'd)

Step

Action

Value(s)

Yes

Check for the following engine mechanical problems:
• Low compression
• Leaking cylinder head gasket
• Worn or incorrect camshaft
• Loose timing belt
Was a problem found?

Verify repair

Go to Step 12

1. Review all the diagnostic procedures within this table.

2. If all procedures have been completed and no

malfunctions have been found, review/inspect the

following:
• Visual/physical inspection.
• Scan Tool data.
• All electrical connections within a suspected circuit

and/or system.

Was a problem found?

Verify repair

Contact

Technical

Assistance

6E1-88 DRIVEABILITY AND EMISSIONS

Detonation/Spark Knock Symptom

Step

Action

Value(s)

Yes

DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks

that change with throttle opening.

Was the On-Board Diagnostic (OBD) System Check

performed?

Go to Step 2

Go to OBD

System

Check

1. Perform a bulletin search.

2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

Verify Repair

Go to Step 3

Was a visual/physical check performed?

Go to Step 4

Go to

Visual/Physic

al Check

1. If scan tool readings are normal (refer to Typical Scan

Values) and there are no engine mechanical faults, fill

the fuel tank with a known quality gasoline that has a

minimum octane rating Showing on the applicable

specification list.

2. Re-evaluate the vehicle performance.

Is detonation present?

Go to Step 5

Verify Repair

1. Check for obvious overheating problems:

• Low engine coolant.
• Restricted air flow to radiator, or restricted water flow

through radiator.

• Incorrect coolant solution. It should be a 50/50 mix of

approved antifreeze/water.

2. If a problem is found, repair as necessary.

Was a problem found?

Verify repair

Go to Step 6

Check fuel pressure. Refer to Fuel System Pressure Test.

Was a problem found?

Verify repair

Go to Step 7

Check items that can cause the engine to run lean.

Refer to Diagnostic Aids in Diagnostic Trouble Code 44 (If

applicable).

Was a problem found?

Verify repair

Go to Step 8

Check spark plugs for proper heat range. Refer to General

Information.

Were incorrect spark plugs installed?

Verify repair

Go to Step 9

1. Remove excessive carbon buildup with a top engine

cleaner. Refer to instructions on the top engine cleaner

can.

2. Re-evaluate vehicle performance.

Is detonation still present?

Go to Step 10

Verify repair

Check for an engine mechanical problem. Perform a

cylinder compression check. Refer to Engine Mechanical.

Was a problem found?

Verify repair

Go to Step 11

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