DTC P0300-P0304 (LDD)
Diagnostic Instructions
DTC Descriptors
DTC P0300 00: Engine Misfire Detected |
DTC P0301 00: Cylinder 1 Misfire Detected |
DTC P0302 00: Cylinder 2 Misfire Detected |
DTC P0303 00: Cylinder 3 Misfire Detected |
DTC P0304 00: Cylinder 4 Misfire Detected |
Circuit/System Description
The engine control module (ECM) uses information from the
crankshaft position sensor in order to determine when an engine
misfire is occurring and uses information from the camshaft
position sensor - intake and camshaft position sensor - exhaust
sensors in order to determine which cylinder is misfiring. By
monitoring variations in the crankshaft rotation speed for each
cylinder, the ECM is able to detect individual misfire events. If
the ECM detects a misfire rate sufficient to cause emission levels
to exceed mandated standards, DTC P0300 00 sets. Under certain
driving conditions, a misfire rate can be high enough to cause the
3-way catalyst to overheat, possibly damaging the converter. The
malfunction indicator lamp (MIL) will flash ON and OFF when
converter overheating, damaging conditions are present and DTC
P0300 00 is set. DTCs P0301 00 - P0304 00 correspond to cylinders
1-4. If the ECM is able to determine that a specific cylinder that
is misfiring, the DTC for that cylinder will set.
Conditions for Running the DTC
• |
DTCs P0010 00, P0011 00, P0013
00, P0014 00, P0016 00, P0017 00, P0101 00, P0102 00, P0103 00,
P0112 00, P0113 00, P0117 00, P0118 00, P0121 00, P0122 00, P0123
00, P0222 00, P0223 00, P0315 00, P0335 00, P0336 00, P0502 00,
P0651 00, and P2135 00 are not set. |
• |
The engine speed is between
600-6 528 RPM. |
• |
The ignition voltage is
between 11-18 V. |
• |
The engine coolant temperature
(ECT) sensor is between -7 to +125°C (+19 to
+257°F). |
• |
The A/C compressor clutch is
not changing states. |
• |
The fuel tank level is greater
than 15%. |
• |
The ECM is not in fuel cut-off
or deceleration fuel cut-off mode. |
• |
The ECM is not receiving a
rough road signal. |
• |
The throttle angle is steady
within 5%. |
• |
The throttle angle is greater
than 3% when the vehicle speed is greater than 5 km/h (3
MPH). |
• |
The transmission is not
changing gears. |
• |
The antilock brake system
(ABS) and the traction control system, if equipped, is not
active. |
• |
DTCs P0300 00, P0301 00, P0302
00, P0303 00, and P0304 00 run continuously when the above
conditions are met. |
Conditions for Setting the DTC
The ECM is detecting a crankshaft rotation speed variation
indicating a misfire sufficient to cause emission or catalyst
damaging levels to exceed mandated standards.
Action Taken When the DTC Sets
DTCs P0300 00, P0301 00, P0302 00, P0303 00 and P0304 00 are
Type A (MIL flashing) or Type B DTCs.
Conditions for Clearing the DTC
DTCs P0300 00, P0301 00, P0302 00, P0303 00 and P0304 00 are
Type A (MIL flashing) or Type B DTCs.
Diagnostic Aids
• |
A misfire may only occur when
the engine is under a load or when the engine is cold. |
• |
A misfire DTC may be caused by
an excessive vibration from sources other than the engine. Inspect
for the following possible sources: |
|
- |
A tire or wheel
that is out of round or out of balance |
|
- |
Variable
thickness brake rotors |
|
- |
Certain rough
road conditions |
|
- |
A damaged
accessory drive component or belt |
|
- |
A damaged
reluctor wheel |
• |
High resistance in the
circuits of the injectors may set a misfire DTC without setting an
injector DTC. Test the injector circuits of the affected
cylinder(s) for a high resistance if you suspect a
condition. |
• |
The MIL indicator flashes when
there is an engine misfire. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Fuel System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Special Tools
• |
EL 26792 HEI
Spark Tester |
• |
EN 36012-A
Ignition System Diagnostic Harness |
For equivalent regional tools, refer to
Special Tools .
Circuit/System Verification
1. |
Engine running at the normal
operating temperature, verify there is no abnormal engine
noise. |
2. |
Observe the DTC information
with a scan tool. Verify that DTC P0201 00, P0202 00, P0203 00,
P0204 00, P0315 00, P0335 00, P0336 00, P0351 00, P0352 00, P0353
00, or P0354 00 are not set. |
|
Note: A misfire may
only occur when the engine is under a load. An engine load may be
necessary to verify the condition.
|
3. |
Observe the scan tool Misfire
Current Counter parameters. The Misfire Current Counters should not
be incrementing. |
4. |
Operate the vehicle within the
conditions for running the DTC to verify the DTC does not reset.
You may also operate the vehicle within the conditions that you
observed from the freeze frame/failure records data. |
Circuit/System Testing
1. |
Verify that the following
conditions do not exist: |
|
• |
Vacuum hose splits, kinks, and
incorrect connections |
|
• |
Crankcase ventilation system
for vacuum leaks |
⇒ |
If you find any of the above conditions, repair as
necessary. |
2. |
Ignition OFF, disconnect the
harness connector at the appropriate Q17 Fuel Injector.
|
3. |
Connect a test lamp between
the control circuit terminal B (1.6L) or terminal 2 (1.8L) and the
ignition voltage circuit terminal A (1.6L) or terminal 1
(1.8L). |
4. |
Engine idling, the test lamp
should flash. |
5. |
Ignition OFF, connect the Q17
Fuel Injector connector. Remove the K35 Ignition Coil
Module. |
6. |
Inspect the ignition coil
spark plug boots for the following conditions: |
⇒ |
If you find any of the above conditions, repair as
necessary. |
7. |
Connect the harness connector
to the ignition coil assembly. |
|
Note: It may be
necessary to secure the EN 36012-A Ignition System
Diagnostic Harness to the spark plug boots with electrical
tape.
|
8. |
Install the EN
36012-A Ignition System Diagnostic Harness to the spark
plug boots. |
9. |
Install the EL 26792
HEI Spark Tester between the spark plug boot of the
misfiring cylinder and earth. |
10. |
Connect the remaining wires to
the appropriate cylinders. |
|
Note: An erratic or
weak spark is considered a no spark condition.
|
11. |
Attempt to start the engine
and observe the EL 26792 HEI Spark Tester . The
spark tester should spark. |
12. |
Ignition OFF, remove the spark
plug from the misfiring cylinder. Verify the following conditions
do not exist with the spark plug: |
|
• |
Cracked, worn, incorrectly
gapped |
⇒ |
If there is a condition with the spark plug, replace the spark
plug. |
13. |
Exchange the suspected spark
plug with another cylinder that is operating correctly.
|
14. |
Engine running, observe the
scan tool Misfire Current Counters. The misfire should not follow
the spark plug exchange. |
⇒ |
If the misfire follows the spark plug, replace the
spark plug. |
15. |
If all conditions test normal,
test or inspect for the following: |
Repair Instructions
Repair Verification
1. |
If the customer concern was a
flashing MIL, operate the vehicle within the conditions for running
DTC P0420 00. Refer to
DTC P0420 . |
2. |
Clear the DTCs with a scan
tool |
3. |
Turn OFF the ignition for 60
s. |
5. |
Operate the vehicle within the
conditions for running the DTC. You may also operate the vehicle
within the conditions that you observed from the freeze
frame/failure records. |
6. |
If the DTC fails this
ignition, a misfire still exists. |
|