Isuzu engine C22NE / 22LE / 20LE. Service manual — part 68
DRIVEABILITY AND EMISSIONS 6E1-101
Cuts Out, Misses Symptom (Cont'd)
Step
Action
Value(s)
Yes
No
10
1. Visually/Physically inspect for the following conditions:
• Restricted air intake system. Check for a restricted
air filter element, or foreign objects blocking the air
intake system.
• Check for objects blocking the IAC passage or
throttle bore, excessive deposits in the IAC passage
and on the IAC pintle, and excessive deposits in the
throttle bore and on the throttle plate.
• Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hoses or brake booster hose
disconnected.
Was a problem found?
-
Verify repair
Go to Step 11
11
1. Check the injector connections. If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.
Was a problem found?
-
Verify repair
Go to Step 12
12
1. Perform the Injector Coil/Balance Test.
Was a problem found?
-
Verify repair
Go to Step 13
13
1. Check for fuel in the pressure regulator vacuum hose.
2. If fuel is present, replace the fuel pressure regulator
assembly.
Was a problem found?
-
Verify repair
Go to Step 14
14
Check for proper ignition voltage output with the spark
tester (Use commercially available tool).
Was a problem found?
-
Verify repair
Go to Step 15
15
1. Remove spark plugs and check for gas or oil fouling
cracks, wear, improper gap, burned electrodes of
heavy deposits.
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 16
16
Check for a loose ignition control module ground.
Was a problem found?
-
Verify repair
Go to Step 17
17
Using a Scan Tool, monitor the TP angle with the engine
idling.
Is the TP angle at the specified value and steady?
0%
Go to Step 18
Refer to
Diagnostic
Trouble Code
21 for further
diagnosis
18
Check the PCV passage for proper operation.
Was a problem found?
-
Verify repair
Go to Step 19
6E1-102 DRIVEABILITY AND EMISSIONS
Cuts Out, Misses Symptom (Cont'd)
Step
Action
Value(s)
Yes
No
19
Check the following engine mechanical problems:
• Low compression
• Leaking cylinder head gasket
• Worn or incorrect camshaft
• Sticking or leaking valves
• Valve timing
• Broken valve springs
• Camshaft drive belt slipped or stripped.
Was a problem found?
-
Verify repair
Go to Step 20
20
Check for faulty motor mounts. Refer to Engine
Mechanical for inspection of mounts.
Was a problem found?
-
Verify repair
Go to Step 21
21
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
DRIVEABILITY AND EMISSIONS 6E1-103
Hesitation, Sag, Stumble Symptom
Step
Action
Value(s)
Yes
No
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.
1
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/Physic
al Check
4
1. Check the fuel control heated oxygen sensor (If
applicable). The HO2S should respond quickly to
different to throttle positions. If it doesn't, check for
silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a white
powdery coating. Silicon contamination sends a rich
exhaust signal which causes the ECM to command an
excessively lean air/fuel mixture.
Was a problem found?
-
Verify repair
Go to Step 5
5
Check the fuel pressure. Refer to Fuel System Pressure
Test.
Was a problem found?
-
Verify repair
Go to Step 6
6
Observe the "TP angle" display on the Scan Tool while
slowly increasing throttle pedal.
Does the TP angle display steadily increase from 0% at
closed throttle to 100% at WOT?
-
Go to Step 7
Go to Step 13
7
Monitor "Long Term Fuel Trim" on the Scan Tool.
Is the "Long Term Fuel Trim" in the negative range (rich
condition)?
-
Go to Step 8
Go to Step 9
8
Check items that can cause the engine to run rich.
Refer to Diagnostic Aids in Diagnostic Trouble Code 45 (If
applicable).
Was a problem found?
-
Verify repair
Go to Step 10
9
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 10
10
Check for proper ignition voltage output with spark tester
(Use commercially available tool). Refer to Electronic
Ignition System for the procedure.
Was a problem found?
-
Verify repair
Go to Step 11
6E1-104 DRIVEABILITY AND EMISSIONS
Hesitation, Sag, Stumble Symptom (Cont'd)
Step
Action
Value(s)
Yes
No
11
Check for a loose ignition control module ground.
Was a problem found?
-
Verify repair
Go to Step 12
12
Visually/Physically inspect the secondary ignition wires.
Check for the following conditions.
• Verify that all ignition wire resistance are less than the
specified value.
• Value 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 14
13
Replace the TP sensor.
-
Verify repair
-
14
1. Check the ignition coil secondary resistance.
2. Replace the coil if it is greater than the specified value.
Was a problem found?
2.5 k
Ω
Verify repair
Go to Step 15
15
1. Remove the spark plugs and check for gas or oil
fouling cracks, wear, improper gap, burned electrodes
of heavy deposits.
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 16
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
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
18
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.
3. If a problem is found, repair as necessary.
Was a problem found?
-
Verify repair
Contact
Technical
Assistance
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