Isuzu 4ja1, Workshop Manual

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6E-238 Engine Control System (4JH1)
Important:
The following symptom tables contain groups of
possible causes for each symptom. The order of these
procedures is not important. If the scan tool readings do
not indicate the problems, then proceed in a logical
order, easiest to check or most likely to cause first. In
order to determine if a specific vehicle is using a
particular system or component, refer to Engine
Controls Schematics for an application.
Use the following tables when diagnosing a symptom
complaint:
•
Intermittent Conditions
•
Hard Start
•
Rough, Unstable, or Incorrect Idle and Stalling
•
Cuts Out, Misses
•
Surge/Chuggles
•
Lack of Power, Sluggishness, or Sponginess
•
Hesitation, Sag, Stumble
•
Fuel Knock/Combustion Noise
•
Poor Fuel Economy
•
Excessive Smoke (Black Smoke)
•
Excessive Smoke (White Smoke)
Intermittent Conditions
Checks Action
DEFINITION:The problem is not currently present but is indicated in DTC History.
OR
There is a customer complaint, but the symptom cannot currently be duplicated, if the problem is not DTC related.
Preliminary Checks
•
Refer to Symptoms – Engine Controls before starting.
Harness/Connector Many intermittent open or shorted circuits are affected by harness/connector
movement that is caused by vibration, engine torque, bumps/rough pavement, etc.
Test for this type of condition by performing the applicable procedure from the
following list:
•
Move related connectors and wiring while monitoring the appropriate scan tool data.
•
Move related connectors and wiring with the component commanded ON, and OFF,
with the scan tool. Observe the component operation.
•
With the engine running, move related connectors and wiring while monitoring
engine operation.
If harness or connector movement affects the data displayed, component/system
operation, or engine operation, inspect and repair the harness/connections as
necessary.
Refer to Electrical Connections or Wiring.