Isuzu 1999 RODEO Workshop Manual page 823

6E1–196 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
f Substitute a known good coil – Swap the ignition coils
and retest. If misfire follows the coil, replace the ignition
coil.
If the misfire is random, check for the following conditions:
f System grounds – Ensure all connections are clean
and properly tightened.
f Air induction system – Check for disconnected or
damaged vacuum hoses, incorrectly installed or faulty
PCV valve, or for vacuum leaks at the throttle body,
EGR valve, and intake manifold mounting surfaces.
f Fuel pressure – Perform a fuel system pressure test.
A faulty fuel pump, plugged filter, or faulty fuel system
pressure regulator will contribute to a lean condition.
f Excessive engine vibration – This may falsely set a
P0301. Refer to Engine Mechanical Diagnosis to
check for a falsely Mechanical condition or component.
f Injector(s) – Perform an injector coil/balance test to
locate faulty injector(s) contributing to a lean or
flooding condition. In addition to the above test, check
the condition of the injector O–rings.
f EGR – Check for a leaking valve, adapter, or feed pipes
which will contribute to a lean condition or excessive
EGR flow.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the Diagnostic Trouble Code to
be set occurs. This may assist in diagnosing the
condition.