NP Gents... Just know that I was more interested in the
Historical Importance of the Delphi Brand as per our GMT360 History along with presenting the images of these OEM COPs "Strictly for The Purists" among us... and so the Title of this Post is of course, Self Explanatory.
But as Tom (
@TJBaker57) points out... Regardless of whether you are replacing COP(s) with NEW or USED Coil Over Plug Unit(s) as needed... It makes perfect sense to
"Verify WHY ...BEFORE You BUY...." and only replace the Damaged COPs
. This On-Topic Training Video on "How To Test COPs using Many Different Methods" is very much worth a look or two:
NOTE:
Testing COPs "In Situ" allows for the Stress of Compression and the Fuel to Air Ratios delivered to each Cylinder provides a more realistic circumstance of having High Atmospheric Pressure working to defeat the Spark Events. ONLY an Oscilloscope is capable to performing this Diagnostic and with the use of a Paddle or Coin Sensor... it becomes very straightforward. Static Bench Tests of COPs and Spark Plugs will only get you so far!
The Attached Images are of a "Known GOOD COP Wave Form" well explained for Novice Oscilloscope Techs the DIFFERENCES between what is happening of the Primary Side "Charging" side of the COPs and What is happening on the Secondary Side of the "Fire" making areas of the COPs:
Divide your Spark Voltage in HALF with a Black Line to see Which side of the COP is suffering problems!