Step | Action | Value(s) | Yes | No |
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Engine Performance diagnosis procedures are covered in Engine Controls and should be consulted for diagnosis of any Driveability, Emissions, or Service Engine Soon lamp complaint. Notice: The following diagnosis information covers common problems and possible causes. When the proper diagnosis is made, the problem should be corrected by adjustment, repair or part replacement as required. Refer to the appropriate section of the manual for these procedures This diagnostic table will isolate any engine misfire due to a mechanical problem such as a faulty camshaft, leaking headgasket, etc. However, this table will not isolate a crossed injector wire, faulty injector, or any other component failure that may cause a misfire. Therefore, the On-Board Diagnostic System Check must be performed first, in order to ensure the correct table is followed for diagnosis of a misfire. Refer to Engine Controls first, then, if necessary, refer to this table. | ||||
1 |
Is the noise timed to the crankshaft speed? | -- | ||
2 |
Does the engine continue to misfire? | -- | System OK | |
3 | Check to see if the noise is timed to the camshaft speed. Is the noise timed to the camshaft speed? | -- | ||
4 |
Does the engine continue to misfire? | -- | System OK | |
5 |
Is the camshaft within specifications? | -- | ||
6 | Replace the camshaft. Refer to Camshaft Replacement . Does the engine continue to misfire? | -- | System OK | |
7 |
Are the repairs complete? | -- | System OK | -- |
Checks | Action | ||||||||||||||||||||||
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Engine performance diagnosis procedures are covered in Engine Controls and should be consulted for diagnosis of any Driveability, Emissions, or Malfunctioning Indicator Lamp (MIL) concerns. The following diagnosis covers common concerns and possible causes. When the proper diagnosis is made, the concern should be corrected by adjustment, repair or replacement as required. Refer to the appropriate section of the service manual for each specific procedure. This diagnostic table will assist in engine misfire diagnosis due to a mechanical concern such as a faulty camshaft, worn or damaged bearings. a crossed injector wire, faulty injector or any other driveability component failure that may cause a misfire. The Powertrain On-Board Diagnostic System checks must be performed first. When using this table to make a Base Engine Misfire diagnosis, begin with the preliminary information below and then proceed to the specific category. | |||||||||||||||||||||||
Preliminary |
DTC P0300 will assist in determining which cylinder or cylinders are misfiring.
Refer to Low or No Oil Pressure . Refer to Excessive Oil Loss . Refer to Engine Compression Test . | ||||||||||||||||||||||
Intake Manifold Leaks | An intake manifold that has a vacuum leak may cause a misfire. Inspect for the following:
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Coolant Consumption | Coolant consumption may or may not cause the engine to overheat. Inspect for the following:
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Oil Consumption |
Refer to Engine Compression Test .
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Abnormal Internal Engine Noises |
Important: A slight COLD knock or piston slapping noise could be considered normal if not present after the engine has reached normal operating temperatures.
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No Abnormal Internal Engine Noise |
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