Chrysler Crossfire. Manual — part 549
(P0300) MULTIPLE CYLINDER MISFIRE (CONTINUED)
When Monitored and Set Condition
•
When Monitored: Any time the engine is running, and the Target Learning Coefficient has been successfully
updated.
•
Set Condition: When more than a 1.0% misfire rate is measured during two trips.
POSSIBLE CAUSES
ENGINE CONTROL RELAY OUTPUT CIRCUIT
FUEL INJECTOR CONTROL CIRCUIT
FUSED IGNITION OUTPUT CIRCUIT
ENGINE MECHANICAL PROBLEM
COIL ON PLUG
COIL ON PLUG DRIVER CIRCUIT
SPARK PLUG
FUEL STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP
FUEL INJECTOR
POWERTRAIN CONTROL MODULE
For a complete Powertrain Control Module Circuit Diagram, (Refer to 9 - ENGINE - SCHEMATICS AND DIA-
GRAMS).
Diagnostic Test
1.
PRE-DIAGNOSTIC CHECK OUT
Note: Always perform diagnostics with a fully charged battery.
Note: Check connectors — Clean/repair as necessary. Poor pin to
terminal connections can set DTCs.
Note: Check for applicable TSBs related to the problem.
Turn the ignition on.
With the DRB III
T
, read PCM DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and
connectors. Repair as necessary.
Perform this procedure prior to symptom diagnosis.
Continue
Go To 2
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(P0300) MULTIPLE CYLINDER MISFIRE (CONTINUED)
2.
CHECK FOR CURRENT DTC
Note: If the PCM detects and stores a DTC, the PCM also stores
the engine/vehicle operating conditions under which the DTC was
set. Some of these conditions are displayed on the DRB III
T
at the
same time the DTC is displayed.
Note: Before erasing stored DTCs, record these conditions.
Attempting to duplicate these conditions may assist when check-
ing for a DTC.
Turn the ignition on.
With the DRB III
T
, erase PCM DTCs.
Note: It maybe necessary to road test the vehicle for this DTC to
set.
With the DRB III
T
, read PCM DTCs.
Did this DTC set again?
Yes
>> Go To 3
No
>> Go To 19
3.
VISUAL AND PHYSICAL INSPECTION
Note: Reviewing the vehicle repair history may aid in the repair of the misfire condition.
Turn the ignition off.
Visually and physically inspect the engine for any of the following conditions:
- Worn serpentine belt
- Binding Engine-Driven accessories
- Misaligned water pump, P/S pump and A/C compressor pulleys
- Improper CKP Sensor mounting
- Poor connector/terminal to component connection, i.e., CKP Sensor, Fuel Injector, Coil On Plug, etc.
- Vacuum leaks
- Restricted Air Intake system
Note: Ensure the powers and grounds for the PCM are functioning properly.
Were any of the above conditions present?
Yes
>> Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST - VER 2.
No
>> Go To 4
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(P0300) MULTIPLE CYLINDER MISFIRE (CONTINUED)
4.
IGNITION SYSTEM OPERATION
With the ignition off.
Remove the Fuel Pump Fuse from the Relay Control Module.
Disconnect the suspect Coil On Plug harness connector.
Remove the Coil On Plug.
Note: Before continuing, inspect the Coil On Plug for the following conditions. Damage or Carbon Tracking
on the Coil or the spark plug insulator boot. If a problem is found, replace the Coil On Plug. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL/IGNITION COIL - REMOVAL).
Install spark testers to the Coil On Plug.
Reconnect the Coil On Plug harness connector to the Coil On Plug.
While cranking the engine, observe the spark coming from the spark testers.
Note: A crisp blue spark should be generated that is able to jump the gap of the spark testers.
Note: Before continuing with next Step, reinstall Fuel Pump Fuse in the Relay Control Module.
Is good spark present?
Yes
>> Go To 5
No
>> Go To 16
5.
SPARK PLUG
With the ignition off.
Remove the Spark Plug.
Inspect the Spark Plug for the following conditions:
- Cracks
- Carbon Tracking
- Foreign Material
- Gap size out of specifications
- Loose or broken electrode
Note: Lightly tap the bottom of the spark plug on a solid surface. The electrode in the spark plug should not
move.
Were any of the above conditions present?
Yes
>> Replace the Spark Plug(s). (Refer to 8 - ELECTRICAL/IGNITION CONTROL/SPARK PLUG -
REMOVAL).
Perform POWERTRAIN VERIFICATION TEST - VER 2.
No
>> Go To 6
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(P0300) MULTIPLE CYLINDER MISFIRE (CONTINUED)
6.
CHECKING FOR POSSIBLE MECHANICAL PROBLEM
Turn the ignition off.
Check for any of the following conditions/mechanical problems:
ENGINE VACUUM - must be at least 330 mm Hg (13 in. Hg) in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks
ENGINE CRANKCASE VENT SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - must not have internal vacuum leaks
FUEL - must be free of contamination
Are there any engine mechanical problems?
Yes
>> Repair as necessary.
Perform POWERTRAIN VERIFICATION TEST - VER 2.
No
>> Go To 7
7.
CHECKING FUEL PRESSURE
WARNING: THE FUEL SYSTEM IS UNDER A CONSTANT PRESSURE (EVEN WITH THE ENGINE OFF).
BEFORE TESTING OR SERVICING ANY FUEL SYSTEM HOSE, FITTING OR LINE, THE FUEL SYSTEM PRES-
SURE MUST BE RELEASED.
With the ignition off.
Install a fuel pressure test gauge to the fuel rail.
Start the engine and observe the fuel pressure reading.
Note: Fuel pressure specification is 3.7 to 4.2 bar (54 to 61 psi).
Choose a conclusion that best matches your fuel pressure reading.
Within Specification
Go To 8
Below Specification
Go To 14
Above Specification
Replace the fuel filter/pressure regulator. (Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/FUEL FILTER
- REMOVAL).
Perform POWERTRAIN VERIFICATION TEST - VER 2.
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