01 4.8l, P1441 and P0300, vacuum leak?

[stumpuller454]

My cousins pickup has a re-occuring p1441 and a new p0300 this week, seems they could be linked to a potential vacuum leak? other than the common intake leaks is there any other regular places for a leak on this model? may sometime this week stick my manometer onit somehow to check it and have a quick visual under hood.

the truck runs fine just has a CEL.

[bradrhale]

isnt a p0300 code random misfire?? have you checked the cap??

[mudseeker]

sounds like an evap problem which could also cause the misfire.

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) monitors the amount of vacuum pressure in the Evaporative Emissions (EVAP) system by monitoring the Fuel Tank Pressure (FTP) sensor signal. The PCM seals the EVAP system by commanding the EVAP purge solenoid OFF and the EVAP vent valve ON. The PCM monitors the fuel tank pressure sensor in order to determine if the EVAP purge solenoid is leaking vacuum to the EVAP system. This Diagnostic Trouble Code (DTC) sets if the vacuum in the EVAP system is more than a predetermined value within a predetermined time.

CONDITIONS FOR RUNNING THE DTC

• DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0443, P0449, P0452, P0453, P1111, P1112, P1114, P1115, P1121 or P1122 are not set.
• No active system voltage DTCs
• The ignition voltage is between 10-18 volts .
• The Barometric Pressure (BARO) is more than 75 kPa .
• The fuel level is between 15-85 percent of full capacity.
• The engine coolant temperature is between 4-30°C (39-86°F) .
• The intake air temperature is between 4-30°C (39-86°F) .
• The start up engine coolant and intake air temperatures are within 8°C (14°F) of each other.
• The Throttle Position (TP) angle is between 0-99.6 percent .

CONDITIONS FOR SETTING THE DTC
The EVAP system develops a vacuum more than a predetermined value when purge is not commanded.

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.
• Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS

IMPORTANT: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Before replacing any components, visually and physically check for the following:

• Mis-routed harness
• Rubbed through wire insulation
• Broken wire inside the insulation
• kinked or damaged vacuum hoses
• Physically damaged system components
• Inspect components and vacuum lines for traces of carbon or other contaminants. The presence of foreign material may be causing a restriction in the system or preventing the solenoid valve from closing properly. Either condition may cause a DTC to set.

For an intermittent condition, refer to Symptoms - Computers and Control Systems. See: Symptom