In this video I will show you how to identify which cylinder is misfiring using just a scan tool and basic test light. This test can be used when you have a constant misfire on one or more cylinders. Once the specific cylinder is isolated, further testing may be needed to determine whether it is a spark, fuel or compression problem.

Engine Performance Diagnostics chapter 22

symptoms 50

  • constant misfire
  • check engine light (P0300, P0305)

fix 50

  • replace faulty ignition coil assembly

test shown enh 50

  • RPM drop test
  • how to short out each plug wire with a test light
  • how to determine if the coil is bad or if there is a control issue

Tools used

  • scan tool
  • incandescent test light

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(Chapter 22) No Spark Troubleshooting, Ignition Coil & Module Testing

Related videos:

How to identify a shorted ignition coil (Honda):


Misfire Case Study (1999 Honda Accord):


Misfire caused by a vacuum leak:


Ignition testing with a scope (Secondary Waveforms) - open plug wire :


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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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