Ses Po300!!!!! [Archive] - GrandAmGT.com Forum

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DXP
06-12-2004, 07:00 AM
So the ses shows up. I take it to Autozone to get read and the code is
PO300
Random/Muttiple Cylinder Misfire

Guys say Plugs and Wires ok Thats obvious but i just replaced the plugs and wires.
I'm going to pull them out and check the gap.
My question is:
Is there any thing besides the plugs and wires that might cause this code??

asepgrad98
06-12-2004, 04:40 PM
DTC P0300
Circuit Description
The powertrain control module (PCM) uses information from the shaft position (CKP) sensors and from the camshaft position (CMP) sensor in order to determine if engine misfire is occurring. By monitoring the variations in the shaft rotational speed for each cylinder, the PCM is able to detect individual cylinder misfire events. A misfire rate that is high enough can cause damage to the 3-way catalytic converter (TWC). The malfunction indicator lamp (MIL) will flash if TWC damaging conditions are present.

Conditions for Running the DTC
DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0125, P0128, P0335, P0336, P0341, P0343, P0502, P0503, P1114, P1115, P1120, P1220, P1221, or P1336 are not set.
The engine speed is between 375-5,001 RPM for an automatic transmission.
The engine speed is between 450-5,001 RPM for a manual transmission.
The ignition voltage is between 10-18 volts.
The engine coolant temperature (ECT) is between -7 to +130C (19-266F).
The fuel level is more than 10 percent.
The throttle position (TP) sensor angle is steady within 1 percent.
The antilock brake system (ABS) and the traction control system are not active.
The transmission is not changing gears.
The secondary air injection (AIR) diagnostic test is not in progress (RPO NC1 only).
The A/C clutch is not changing states.
The PCM is not in fuel shut-off or decel fuel cut-off (DFCO) mode.
The ABS signal is not exceeding rough road thresholds.
Conditions for Setting the DTC
The PCM determines that an emission type misfire is present.
The PCM determines that a catalyst damaging misfire is present.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Diagnostic Aids

Important
Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Verify that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.


Running the vehicle out of fuel causes sufficient misfire to set DTC P0300. A vehicle that is out of fuel may have fuel level DTCs also set.
A restricted fuel filter can cause sufficient misfire to set DTC P0300. Refer to Fuel System Diagnosis .
Excessive vibration from sources other than the engine can cause a misfire DTC. The following are possible sources of vibration:
Variable thickness brake rotor
Drive shaft not balanced
Certain rough road conditions
Observe, if more then one cylinder is misfiring, the scan tool may only display one cylinder misfiring. This will not be apparent until the repair is completed. Also, if an ignition coil ground circuit is open for one side of the engine, the scan tool may only display 2 or 3 cylinders misfiring. Inspect the ground circuit for the ignition coil on the cylinder bank of the engine that has more then one cylinder misfiring.