Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
you need to check to make sure you have no vacuum leak...also remove the plug and recheck the gap,,why you have the plug out,check the compression on the #5 and compare it to the other cylinders to make sure the engine is sound..
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CIRCUIT DESCRIPTION The Crankshaft Position (CKP) sensor is the primary input to determine if misfire is occurring. Engine misfire is detected by monitoring crankshaft speed variations between cylinders. If a crankshaft deceleration occurs during a combustion or power stroke, the control module will compare this change in crankshaft speed to the previous cylinder. If the crankshaft speed change is more than a maximum allowable speed, the misfire is detected. Misfire may occur in a specific cylinder or in all cylinders randomly.When an engine is misfiring, brief decelerations in crankshaft rotational speed will be detected by the CKP. The control module determines which cylinder has misfired based upon the Camshaft Position (CMP) sensor input. Misfire data is stored for each cylinder in separate accumulators. After 100 combustion events, the misfire totals are compared to a calibrated maximum number. If the misfire is excessive, this Diagnostic Trouble Code (DTC) will set.CONDITIONS FOR RUNNING THE DTC IMPORTANT: If start-up ECT is below -7°C (20°F) , misfire detection is delayed until ECT is more than 21°C (70°F) . If start-up ECT is more than -7°C (20°F) , misfire detection begins after a 5 second delay.
CONDITIONS FOR SETTING THE DTC The VCM detects a deceleration in the crankshaft speed characteristic of either an emission type misfire or a catalyst damaging type misfire.ACTION TAKEN WHEN THE DTC SETS If the VCM determines that the engine misfire is significant enough to have a negative impact on emissions, the VCM turns ON the Malfunction Indicator Lamp (MIL) after the misfire has been detected on 2 non-consecutive trips under the same operating conditions. If the misfire is severe enough that catalytic converter damage could result, the MIL flashes while the misfire is present.CONDITIONS FOR CLEARING THE MIL OR DTC
DIAGNOSTIC AIDS The Misfire Index counts the number of misfires. The scan tool can monitor the Misfire Index. There is a current and history misfire counter for each cylinder. Use the current misfire counter in order to determine which cylinder is misfiring or use the history misfire counter for misfires that are not currently present. Many different condition could cause an intermittent misfire.Check for the following conditions:
An intermittent may be caused by any of the following conditions:
Thoroughly inspect any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent and Poor Connections in Diagrams.If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Diagrams.