Isuzu 2000 Trooper Workshop Manual page 1374

Rough, Unstable, or Incorrect Idle, Stalling Symptom
Step
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?
2 Was the "Electric Throttle Control (ETC) System
Check" performed?
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?
4 Was a visual/physical check performed?
5 1. Check the PCM grounds for cleanliness, tightness
and proper routing.
diagrams in Electrical Diagnosis .
2. If a problem is found, repair as necessary.
Was a problem found?
6 Observe the long term fuel trim on the Tech 2.
Is the long term fuel trim significantly in the negative
range (rich condition)?
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?
8 Is the long term fuel trim significantly in the positive
range (lean condition)?
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?
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?
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Action
Refer to the PCM wiring
Value(s) Yes
— Go to Step 2
— Go to Step 3
— Go to Step 14
— Go to Step 5
— Verify repair
Go to Step 7
—
— Verify repair
— Go to Step 9
— Verify repair
Desired Idle
Speed Go to Step 12
6E–505
No
Go to OBD
System
Check
Go to ETC
System
Check
Go to Step 4
Go to
Visual/Physic
al Check
Go to Step 6
Go to Step 8
Go to Step 10
Go to Step 10
Go to Step 10
Go to Step 11