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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0300-P0308: Engine Misfire Detected >> Test Description

Test Description

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step number in the diagnostic procedures.

  1. 2

    Engine misfire can change engine load characteristics which may affect the TP sensor performance diagnostic. Correct any misfire before diagnosing DTC P0121. A malfunctioning injector circuit, crankshaft position system variation not learned, an intermittent CKP sensor condition, incorrect rough road data from the Electronic Brake Control Module (EBCM), etc. may cause a misfire DTC to be set. If any other DTCs except P0121 are set with DTC P0300, diagnose and repair the other DTC before using DTC P0300 procedure.

  2. 3

    The Misfire Bar Graph, or Misfire Current Cyl#, display may normally display a small amount of activity, typically 0-10 counts, but should not steadily increment during an entire 200 revolution test sample period.

  3. 4

    A misfiring or dead cylinder can sometimes affect the misfire counters for other cylinders. When you perform the steps on this procedure, concentrating on the cylinder with the highest level of misfire and correcting the condition, may also correct the other cylinders that indicate misfire. This step splits the procedure between conditions that would cause a specific cylinder to misfire and conditions that would affect all cylinders, causing a random multiple cylinder misfire.
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