Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Service 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
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