Isuzu Trooper (1998-2002 year). Service manual — part 527
6E–478
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
Cuts Out, Misses Symptom
(Cont'd)
Step
No
Yes
Value(s)
Action
20
1. Check the PCV valve for proper operation. Refer to
Crankcase Ventilation System.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 21
21
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 22
22
1. Check the following engine mechanical items.
Refer to
Engine Mechanical for diagnosis
procedures:
D
Low compression
D
Sticking or leaking valves
D
Worn camshaft lobe(s)
D
Camshaft drive belt slipped or stripped
D
Incorrect valve timing
D
Worn rocker arms
D
Broken valve springs
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 23
23
1. Check for faulty motor mounts. Refer to
Engine
Mechanical for inspection of mounts.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 24
24
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 butter
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–479
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom
Step
Action
Value(s)
Yes
No
1
DEFINITION:
Momentary lack of response as the accelerator is
pushed down. Can occur at any vehicle speed. Usually
most pronounced when first trying to make the vehicle
move, as from a stop sign. May cause the engine to stall
if severe enough.
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?
—
Verify repair
Go to
Step 4
4
Was a visual/physical check performed?
—
Go to
Step 5
Go to
Visual/
Physical
Check
5
1. Check the fuel control heated oxygen sensors
(HO2S, B1S1 and B2S1). The fuel control heated
oxygen sensors (HO2S) should respond quickly to
different throttle positions. If they don’t, check them
for silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a
white powdery coating.
Silicon contamination causes a high but false
HO2S signal voltage (rich exhaust indication).
The PCM will then reduce the amount of fuel
delivered to the engine, causing a severe
driveability problem. For more information, refer
to
Powertrain Control Module (PCM) and Sensors.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 6
6
1. Check the fuel pressure. Refer to
Fuel System
Pressure Test.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 7
7
Observe the TP 1, 2 angle display on the Tech 2 while
slowly increasing accelerator pedal depression.
Does the TP angle display steadily increase from 8
∼
10% at closed throttle to 90
∼
92% at WOT?
—
Go to
Step 8
Go to
Step 9
8
Monitor 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 9
Go to
Step 10
9
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 11
6E–480
6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom
(Cont'd)
Step
No
Yes
Value(s)
Action
10
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 11
11
1. Check for proper ignition voltage output with spark
tester J 26792 (ST-125). Refer to
Electronic Ignition
System for the procedure.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 12
12
1. Check for a loose ignition coil ground and ION
Sensing module circuit.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 13
13
1. Check the ignition coils for cracks or carbon
tracking.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 14
14
1. Remove spark plugs and check for wet plugs,
cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to
Electronic Ignition
System.
NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 15
15
1. Check the PCM grounds for clearness, 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 16
16
1. Check the MAF sensor connections.
2. If a problem is found, replace the faulty terminals as
necessary. Refer to
Electrical Diagnosis for wiring
repair procedures.
Was a problem found?
—
Verify repair
Go to
Step 17
6E–481
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom
(Cont'd)
Step
No
Yes
Value(s)
Action
17
1. Visually/physically check vacuum hoses for splits,
kinks, and proper connections and routing as
shown on the “Vehicle Emission Control
Information” label.
2. If a problem is found, repair as necessary.
Was a problem found?
—
Verify repair
Go to
Step 18
18
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 butter
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
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