Isuzu Rodeo UE. Service manual — part 375
6E2–255
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0301 Cylinder 1 Misfire Detected
Circuit Description
The powertrain control module (PCM) has the ability to
detect a misfire by monitoring the 58X reference and the
camshaft position sensor input signals. If the PCM
detects a crankshaft speed variation that indicates 1% or
more of cylinder firing events are misfires, the PCM will
disable the torque converter clutch (TCC). If the RPM
variation detected indicates a misfire, the PCM attempts
to calculate which cylinder is misfiring by associating
crankshaft angle (using the camshaft position sensor
signal) with the RPM variation (using the 58X reference).
If cylinder #1 is isolated as the misfiring cylinder, DTC
P0301 will set.
If the ABS Rough Road sensor input signal to the PCM
determines that a rough road condition is present, the
misfire diagnostic will be temporarily disabled.
Conditions for Setting the DTC
f
None of the following DTCs occur: TP sensor, MAF
sensor, camshaft position sensor, vehicle speed
sensor, ECT sensor, ABS rough road sensor,
crankshaft position sensor.
f
The engine speed is between 600 and 6250 RPM.
f
The system voltage is between 11 and 16 volts.
f
The ECT indicates an engine temperature between
–7
°
C (28
°
F) and 120
°
C (248
°
F).
f
The throttle angle is steady.
f
The PCM is detecting a crankshaft RPM variation that
indicates a misfire on cylinder #1 sufficient to cause
three-way catalytic converter damage or emissions
levels to exceed mandated standard.
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
The PCM will store conditions which were present
when the DTC 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 ignition cycle in which the diagnostic has
been run and the fault condition is no longer present.
f
A history DTC P0301 will clear after 40 consecutive
ignition cycles occur without a fault.
f
DTC P0301 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
f
System grounds – Ensure all connections are clean
and properly tightened.
f
Injector – Perform the injector coil/balance test to
locate a faulty injector that contributes to a lean
condition on the affected cylinder. In addition to the
above test, check the condition of the injector O-ring.
f
Faulty spark plug – Check for a cracked insulator,
carbon tracking, incorrect gap, and worn electrodes.
f
Damaged or faulty ignition coil – Check for cracks or
other damage.
f
Substitute a known good coil – Swap the ignition coils
and retest. If the misfire follows the coil, replace the
ignition coil.
DTC P0301 — Cylinder 1 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 the engine. Run the engine at idle.
2. Review and record Tech 2 Freeze Frame data.
3. Monitor “Misfire Cur. #1” on the Tech 2.
Is “Misfire Cur. #1” increasing (indicating a misfire
currently occurring)?
—
Go to
Step 4
Go to
Step 3
3
Monitor “Misfire Hist. #1” while operating the vehicle to
duplicate the conditions present when the DTC was set
(as defined by the Freeze Frame data recorded in Step
2).
Is “Misfire Hist. #1” increasing (indicating a misfire
currently occurring)?
—
Go to
Step 4
Refer to
Diagnostic
Aids
6E2–256
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0301 — Cylinder 1 Misfire Detected
(Cont'd)
Step
No
Yes
Value(s)
Action
4
1. Visually and physically inspect the vacuum hoses
for splits, kinks, and improper connections. Also,
inspect the intake manifold for a vacuum leak.
2. If a problem is found, repair it as necessary.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 5
5
1. Install a spark tester at the spark plug end of the
cylinder #1 ignition coil.
2. Crank the engine while observing the spark tester.
A crisp, blue spark should be observed.
Is adequate spark present?
—
Go to
Step 8
Go to
Step 6
6
1. Remove and visually/physically inspect the ignition
coil associated with cylinder #1. Ensure that the coil
is free of cracks and carbon tracking.
2. If a problem is found, replace the damaged ignition
coil as necessary.
Did the visual inspection reveal a problem?
—
Verify repair
Go to
Step 7
7
1. Measure the ignition coil primary resistance.
2. If resistance is not within the specified value,
replace the faulty ignition coil.
Did the ignition coil require replacement?
2.6 - 2.7 k
W
Verify repair
Go to
Step 12
8
Remove the cylinder #1 spark plug and visually inspect
the spark plug electrode.
Does the inspection reveal excessive fouling?
—
Go to
Contaminatio
n Diagnosis
chart in
Engine
Mechanical
Diagnosis
Go to
Step 9
9
1. Visually inspect the spark plug insulator for cracks,
carbon tracking, or other damage.
2. If the spark plug is damaged, replace the spark plug.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 10
10
1. Perform the “Injector Coil/Balance Test.”
2. If any faulty injectors are found, replace them as
necessary.
Did any of the injectors require replacement?
—
Verify repair
Go to
Step 11
11
1. Inspect the injector O-rings for a vacuum leak.
2. If a problem is found, repair it as necessary.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 12
12
Check for an engine mechanical problem. Refer to
Engine Mechanical Diagnosis to diagnose and repair
the following conditions:
f
A faulty or incorrect camshaft
f
Leaking or sticky valves or rings
f
Excessive valve deposits
f
Loose or worn rocker arms
f
Weak valve springs
f
A leaking head gasket
Was a basic engine mechanical problem found?
—
Verify repair
Refer to
Diagnostic
Aids
6E2–257
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0302 Cylinder 2 Misfire Detected
Circuit Description
The powertrain control module (PCM) has the ability to
detect a misfire by monitoring the 58X reference and the
camshaft position sensor input signals. If the PCM
detects crankshaft speed variations that indicate 1% or
more of cylinder firing events are misfires, the PCM will
disable the torque converter clutch (TCC). If the RPM
variation detected indicates a misfire, the PCM attempts
to calculate which cylinder is misfiring by associating
crankshaft angle (using the camshaft position sensor
signal) with the RPM variation (using the 58X reference).
If cylinder #2 is isolated as the misfiring cylinder, DTC
P0302 will set.
If the ABS Rough Road sensor input signal to the PCM
determines that a rough road condition is present, the
misfire diagnostic will be temporarily disabled.
Conditions for Setting the DTC
f
None of the following DTCs occur: TP sensor, MAF
sensor, camshaft position sensor, vehicle speed
sensor, ECT sensor, ABS rough road sensor,
crankshaft position sensor.
f
The engine speed is between 600 and 6250 RPM.
f
The system voltage is between 11 and 16 volts.
f
The ECT indicates an engine temperature between
–7
°
C (28
°
F) and 120
°
C (248
°
F).
f
The throttle angle is steady.
f
The PCM is detecting a crankshaft RPM variation that
indicates a misfire on cylinder #2 sufficient to cause
three-way catalytic converter damage or emissions
levels to exceed mandated standard.
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
The PCM will store conditions which were present
when the DTC 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 ignition cycle in which the diagnostic has
been run and the fault condition is no longer present.
f
A history DTC P0302 will clear after 40 consecutive
ignition cycles occur without a fault.
f
DTC P0302 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
f
System grounds – Ensure all connections are clean
and properly tightened.
f
Injector – Perform the injector coil/balance test to
locate a faulty injector that contributes to a lean
condition on the affected cylinder. In addition to the
above test, check the condition of the injector O-ring.
f
Faulty spark plug – Check for a cracked insulator,
carbon tracking, incorrect gap, and worn electrodes.
f
Damaged or faulty ignition coil – Check for cracks,
carbon tracking or other damage.
f
Substitute a known good coil – Swap the ignition coils
and retest. If the misfire follows the coil, replace the
ignition coil.
DTC P0302 – Cylinder 2 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 the engine. Run the engine at idle.
2. Review and record Tech 2 Freeze Frame data.
3. Monitor “Misfire Cur. #2” on the Tech 2.
Is “Misfire Cur. #2” increasing (indicating a misfire
currently occurring)?
—
Go to
Step 4
Go to
Step 3
3
Monitor “Misfire Hist. #2” while operating the vehicle to
duplicate the conditions present when the DTC was set
(as defined by the Freeze Frame data recorded in Step
2).
Is “Misfire Hist. #2” increasing (indicating a misfire
currently occurring)?
—
Go to
Step 4
Refer to
Diagnostic
Aids
6E2–258
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
DTC P0302 – Cylinder 2 Misfire Detected
(Cont'd)
Step
No
Yes
Value(s)
Action
4
1. Visually and physically inspect the vacuum hoses
for splits, kinks, and improper connections. Also,
inspect the intake manifold for a vacuum leak.
2. If a problem is found, repair it as necessary.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 5
5
1. Install a spark tester at the spark plug end of the
cylinder #2 ignition coil.
2. Crank the engine while observing the spark tester.
A crisp, blue spark should be observed.
Is adequate spark present?
—
Go to
Step 8
Go to
Step 6
6
1. Remove and visually/physically inspect the ignition
coil associated with cylinder #2. Ensure that the coil
is free of cracks and carbon tracking.
2. If a problem is found, replace the damaged ignition
coil as necessary.
Did the visual inspection reveal a problem?
—
Verify repair
Go to
Step 7
7
1. Measure the ignition coil primary resistance.
2. If resistance is not within the specified value,
replace the faulty ignition coil.
Did the ignition coil require replacement?
2.6 - 2.7 k
W
Verify repair
Go to
Step 12
8
Remove the cylinder #2 spark plug and visually inspect
the spark plug electrode.
Does the inspection reveal excessive fouling?
—
Go to
Contaminatio
n Diagnosis
chart in
Engine
Mechanical
Diagnosis
Go to
Step 9
9
1. Visually inspect the spark plug insulator for cracks,
carbon tracking, or other damage.
2. If the spark plug is damaged, replace the spark plug.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 10
10
1. Perform the “Injector Coil/Balance Test.”
2. If any faulty injectors are found, replace them as
necessary.
Did any of the injectors require replacement?
—
Verify repair
Go to
Step 11
11
1. Inspect the injector O-rings for a vacuum leak.
2. If a problem is found, repair it as necessary.
Did the inspection reveal a problem?
—
Verify repair
Go to
Step 12
12
Check for an engine mechanical problem. Refer to
Engine Mechanical Diagnosis to diagnose and repair
the following conditions:
f
A faulty or incorrect camshaft
f
Leaking or sticky valves or rings
f
Excessive valve deposits
f
Loose or worn rocker arms
f
Weak valve springs
f
A leaking head gasket
Was a basic engine mechanical problem found?
—
Verify repair
Refer to
Diagnostic
Aids
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