Isuzu Rodeo UE. Manual — part 206
6E1–195
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0301 RANDOM/MULTIPLE CYLINDER
MISFIRE DETECTED
D06RX050
Circuit Description
If the PCM determines that the engine is misfiring and can
determine the actual cylinder that is misfiring then it will
log the individual trouble code for that cylinder P0301.
This is normally the situation in the case of a failed fuel
injector, spark plug or ignition lead.
Conditions for Setting the DTC
f
None of the following Diagnostic Trouble Codes are
present: TP sensor, MAP sensor, CMP sensor, VSS,
ECT, CKP sensor.
f
The engine speed is between 600 and 6250 RPM.
f
The system voltage is between 11 and 16 volts.
f
The engine coolant temperature sensor (ECT)
indicates an engine temperature between –6.75
°
C
(20
°
F) and 120
°
C (248
°
F).
f
Throttle angle is steady and throttle angle changes less
than 2.73% per 100 milliseconds.
f
The PCM detects a crankshaft RPM variation
indicating a misfire that is sufficient to cause catalytic
converter damage or emissions levels to exceed the
mandated standard.
f
TP sensor reads less than 3.125%.
f
Vehicle speed is greater than 33km/h (20mph).
f
Engine under load.
Action Taken When the DTC Sets
f
The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
f
If the misfire is severe enough to cause possible
catalyst damage, the PCM will flash the MIL for as long
as the misfire remains at catalyst damaging levels.
f
”Open Loop” fuel control will be in effect.
f
The PCM will store conditions which were present
when the Diagnostic Trouble Code was set as Freeze
Frame and in the Failure Records data.
Conditions for Clearing the MIL/DTC
f
The PCM will turn the MIL OFF on the third consecutive
trip cycle during which the diagnostic has been run and
the fault condition is no longer present.
f
A history Diagnostic Trouble Code P0301 will clear
after 40 consecutive warm–up cycles have occurred
without a fault.
f
Diagnostic Trouble Code P0301 can be cleared by
using the Scan Tool’s ”Clear Info” function.
Diagnostic Aids
The Tech 2 displays ”Misfire Cur. # 1 through #4” can be
useful to determine whether the misfire is isolated to a
single cylinder.
f
Damaged or faulty ignition coils – Check for cracks or
other damage.
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.
6E1–197
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DTC P0301 – Random/Multiple Cylinder Misfire Detected
Step
Action
Value(s)
Yes
No
1
Was the ”On–Board Diagnostic (OBD) System Check”
performed?
—
Go to Step 2
Go to OBD
System
Check
2
1. Start and idle the engine.
2. Review and record the Tech 2 Freeze Frame data.
3. Operate the vehicle to duplicate the conditions
present when the Diagnostic Trouble Code was set
(as defined by the Freeze Frame data).
4. Monitor the Tech 2 ”Misfire Cur. #” display for each
cylinder.
Is ”Misfire Cur. #” display increasing for any cylinder
(indicating a misfire currently occurring)?
—
Go to Step 3
Refer to
Diagnostic
Aids
3
1. Visually and physically inspect the vacuum hoses
for splits, kinks, and improper connections.
2. If a problem is found, repair or replace the vacuum
hoses as necessary.
Did your inspection reveal a problem?
—
Verify repair
Go to Step 4
4
1. Visually and physically inspect the following areas
for vacuum leaks:
f
Intake manifold
f
Injector O–rings
f
EGR valve
f
EGR feed pipes
Did your inspection reveal a vacuum leak?
—
Verify repair
Go to Step 5
5
Inspect the crankcase ventilation valve for proper
installation or a cracked hose.
Did your inspection reveal a problem?
—
Verify repair
Go to Step 6
6
1. Remove and visually/physically inspect the ignition
coils. Ensure that the coils are free of cracks and
carbon tracking.
2. If a problem is found, replace the damaged ignition
coils.
Was a problem found?
—
Verify repair
Go to Step 7
7
1. Install a spark tester at the spark plug end of the
ignition wire for the cylinder that is indicated by the
”Misfire Cur. Counters” or ”Misfire Hist. Counters”
as having the most severe misfire (largest number
of counts).
2. Crank the engine while observing the spark tester. A
crisp, blue spark should be observed.
Is adequate spark present?
—
Go to Step
12
Go to Step 8
8
1. Remove the spark plugs from the cylinders that
were indicated as misfiring.
2. Visually inspect the spark plug electrodes.
Does your inspection reveal any spark plugs exhibiting
excessive fouling?
—
Go to Engine
Mechanical
Diagnosis
Go to Step 9
6E1–198
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DTC P0301 – Random/Multiple Cylinder Misfire Detected
(Cont'd)
Step
No
Yes
Value(s)
Action
9
1. Visually inspect the spark plug insulators for cracks,
carbon tracking, or other damage.
2. If a problem is found, replace the faulty spark
plug(s) as necessary.
Did your inspection reveal a problem?
—
Verify repair
Go to Step
10
10
Replace the ignition control module.
—
Verify repair
—
11
1. Inspect the PCM injector grounds, power grounds
and sensor grounds to ensure that they are clean,
tight and in their proper locations.
2. If a problem is found, correct the faulty ground
condition as necessary.
Did your inspection reveal a poor ground?
—
Verify repair
Go to Step
12
12
1. Perform the ”Fuel System Pressure Test”
procedure.
2. If a problem is found, repair as necessary (refer to
Engine Fuel or Fuel Metering System).
Was a fuel system problem found?
—
Verify repair
Go to Step
13
13
1. Check the fuel for excessive water, alcohol, or other
contaminants (refer to Diagnosis in Engine Fuel for
procedure).
Was the fuel contaminated?
—
Verify repair
Go to Step
14
14
1. Perform the ”Injector Coil/Balance Test.”
2. If a problem is found, replace the faulty injector(s) as
necessary.
Did any of the injectors require replacement?
—
Verify repair
Go to Step
15
15
Check for an engine mechanical problem. Refer to
Engine Mechanical Diagnosis to diagnose the following
conditions:
f
A faulty or incorrect camshaft
f
Leaking or sticky valves or piston rings
f
Excessive valve deposits
f
Loose or worn rocker arms
f
Weak valve springs
f
Incorrect valve timing
f
A leaking head gasket
f
A loose or broken motor mount
—
Verify repair
—
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