This vehicle came in with a long history, a severe misfire complaint that two shops couldn’t fix, and lots of parts changing along the way. Testing and careful analysis led to a surprising fix. All of the testing methods shown can be applied to any vehicle with a coil-on-plug ignition system.

Engine Performance Diagnostics chapter 1 page 2, 14 - 21

symptoms 50

  • severe misfire
  • check engine light (P0300)
  • intermittent backfiring through intake

fix 50

  • correct swapped #4 and #6 ignition coil connectors

test shown enh 50

  • how to perform a cylinder balance test (power balance)
  • using a coil-on-plug adapter with a lab scope for secondary ignition waveforms
  • analyzing secondary waveform attributes during misfire diagnosis
  • how to perform a relative compression test
  • how to use a coil current ramp as a sync trace
  • setting up a lab scope for various testing methods
  • how to use an in-cylinder pressure transducer to verify spark timing
  • how to get a primary ignition waveform (safely)

Tools used

  • scan tool
  • Picoscope automotive 4 channel lab scope
  • Fluke PV350 pressure transducer
  • inductive low amp probe

end faq

{accordionfaq faqid=accordion15 faqclass="dotluvfaq help2 aligncenter headerbackground headerborder contentbackground contentborder round7" active=item0}


(Chapter 1) Misfire ID, Compression Tests, Vacuum Leaks, Fuel Trim, Head Gasket, Restricted Exhaust, Low Power, DMM

Related videos:

2004 Mazda MPV Low Power Case Study:


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


Secondary Ignition Waveforms (common faults):


How to determine which cylinder is misfiring (cylinder drop test):


How to check for a jumped timing chain or belt:


end faq

{accordionfaq faqid=accordion3 faqclass="darkhivefaq defaulticon headerbackground headerborder contentbackground contentborder round5" active=item0}

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.

Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium. There is a 14 day free trial.

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!