Relative compression test using the Snap-On Verus. You do not need a Snap-on scope to do these tests. The same procedure can be followed using any Lab Scope.

Engine Performance Diagnostics chapter 1 pages 17-22

test shown enh 50

  • how to use starter current to determine cylinder compression
  • how to synchronize the starter current pattern with an ignition firing event to determine exact cylinder location

Tools used

  • lab scope
  • low amp probe
  • high amp probe (preferred)
  • secondary ignition pick-up

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

Related videos:

How to perform a compression test with a scope (Picoscope):


Relative Compression Testing Variables (3 cylinders have no compression):


How to check for a jumped timing chain or belt:


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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.

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!