Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 371

6E–514

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Sparks Knock Symptoms

 

Step

Action

Value(s)

Yes

No

1

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

2

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

3

Was a visual/physical check performed?

—

Go to 

Step 4

Go to 

Visual/

Physical

Check

4

If Tech 2 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 of 87 and re-evaluate the
vehicle performance.

Is detonation present?

—

Go to 

Step 5

Verify repair

5

1. Check the transmission range switch circuit.  Use a

Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.

2. If a problem is found, diagnose and repair the

transmission range switch as necessary (refer to
4L30-E Automatic Transmission Diagnosis).

Was a problem found?

—

Verify repair

Go to 

Step 6

6

1. Check TCC operation.  Refer to 

4L30-E

Transmission Diagnosis.

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

Was a problem found?

—

Verify repair

Go to 

Step 7

7

1. Check for obvious overheating problems:

D

Low engine coolant.

D

Restricted air flow to radiator, or restricted
water flow through radiator.

D

Correct coolant solution should be a 50/50 mix
of approved antifreeze/coolant and water.
Refer to 

Engine Cooling.

D

EGR operation.  Refer to 

DTC P0401.

D

ION sensing module fault.

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

Was a problem found?

—

Verify repair

Go to 

Step 8

8

1. Ignition “OFF”.
2. Disconnect the ION sensing module.
3. Disconnect the PCM.

Is the action complete?

—

Go to 

Step 9

—

9

Check the ION sensing harness between the PCM
(F68) and ION sensing module circuit (RED Wire) at
the Kl line harness connector.

Was a problem found?

—

Verify repair

Go to 

Step 10

6E–515

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Sparks Knock Symptoms

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

1. Disconnect the ignition coil.

Is the action complete?

—

Go to 

Step 11

—

11

Check the ION sensing harness between the ignition
coil and ION sensing module circuit at the DC motor
harness connector.

Was a problem found?

—

Verify repair

Go to 

Step 12

12

Check the following items;

1. Ignition coil and ignition coil circuit.
2. Ignition coil ground circuit for a poor connection.
3. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to 

Step 13

13

Replace the Ignition coil.

Is the action complete?

—

Verify repair

Go to 

Step 14

14

Check the following items;

1. ION sensing module ground circuit for a poor

connection.

2. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Go to 

Step 10

Go to 

Step 16

15

Replace the ION sensing module.

Is the action complete?

—

Verify repair

Go to 

Step 16

16

1. Check fuel pressure.  Refer to Chart  Fuel System

Pressure Test.

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

Was a problem found?

—

Verify repair

Go to 

Step

17

17

1. Check items that can cause an engine to run lean

(long term fuel trim significantly in the positive
range).  For a lean condition, refer to 

Diagnostic

Aids in DTC P0171 Diagnostic Support.

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

Was a problem found?

—

Verify repair

Go to 

Step 18

18

1. Spark plugs for proper heat range.  Refer to 

General

Information.

2. If incorrect spark plugs are installed, replace spark

plugs as necessary.

Did any spark plugs require replacement?

—

Verify repair

Go to 

Step 19

19

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 20

Verify repair

6E–516

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Sparks Knock Symptoms

  (Cont'd)

Step

No

Yes

Value(s)

Action

20

1. Check for an engine mechanical problem.  Perform

a cylinder compression check.  Refer to 

Engine

Mechanical.

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

Was a problem found?

—

Verify repair

Go to 

Step 21

21

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

D

Visual/physical inspection

D

Tech 2 data

D

Freeze Frame data/Failure Records buffer

D

All electrical connections within a suspected
circuit and/or system.

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

Was a problem found?

—

Verify repair

Contact

Technical

Assistance

6E–517

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

 

Step

Action

Value(s)

Yes

No

1

DEFINITION:
Engine runs unevenly at idle.  If severe, the engine or
vehicle may shake.  Engine idle speed may vary in
RPM.   Either condition may be severe enough to stall
the engine.

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to 

Step 2

Go to 

OBD

System

Check

2

Was the “Electric Throttle Control (ETC) System
Check” performed?

—

Go to 

Step 3

Go to 

ETC

System

Check

3

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?

—

Go to 

Step 14

Go to 

Step 4

4

Was a visual/physical check performed?

—

Go to 

Step 5

Go to 

Visual/

Physical

Check

5

1. Check the PCM grounds for cleanliness, tightness

and proper routing.  Refer to the PCM wiring
diagrams in 

Electrical Diagnosis.

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

Was a problem found?

—

Verify repair

Go to 

Step  6

6

Observe the long term fuel trim on the Tech 2.

Is the long term fuel trim significantly in the negative
range (rich condition)?

—

Go to 

Step 7

Go to 

Step 8

7

1. Check items that can cause the engine to run rich.

Refer to 

Diagnostic Aids in DTC P0172 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to 

Step 10

8

Is the long term fuel trim significantly in the positive
range (lean condition)?

—

Go to 

Step 9

Go to 

Step 10

9

1. Check items that can cause the engine to run lean.

Refer to 

Diagnostic Aids in DTC P0171 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to 

Step 10

10

1. Check for incorrect idle speed.  Ensure that the

following conditions are present:

D

The engine is fully warm.

D

The accessories are “OFF”.

2. Using a Tech 2, monitor the Engine Speed.

Is the Engine Speed within the specified values?

Desired Idle

Speed

Go to 

Step 12

Go to 

Step 11