GM Truck V8 Misfire Diagnostics: SMA "O" School vs, "O"scillosopes

mrrsm

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Oct 22, 2015
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It might seem from some of my own recent threads and postings about the use of the PICO-Scope and Hantek Oscilloscopes that THESE Diagnostic Tools are not only the BEST way to diagnose Auto Engine Problems... but the ONLY Real Way to do so.

But Hold ON! Not so Fast, Folks. My thinking is that these 'Fancy Tools' are ADDITIVE to our list of possible solutions and should NOT become the sole method and approach to performing Engine Diagnostics.

What I do LIKE about them is their often Magical Nature at revealing what is REALLY happening inside of Sick Engines ...often without having to do excessive labor to make such discoveries.

And to amplify this message on how "Bright & Shiny Objects" can often lure us astray ... Eric "O" from South Main Auto puts on a superb, contemporary (09/10/2021) GM V8 Engine Misfire Clinic involving an intractable P0300 Code in a Silverado Truck. You'll get to see him using a whole Raft of Special Tools and Investigative Ideas on how to chase this common issue to ground.

In this example, he uses his Old School Skill Set and Methods to prove that relying entirely on ONE Technique, ONE Tool... or your FIRST Impression... can often be the wrong way to go when working towards solving the actual issues at hand. The BEST Technique here is to come at these issues from MANY directions before arriving at your final conclusions:

 
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mrrsm

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Having watched this Video many times (as I always do when viewing anything from SMA to learn as much as possible)... I noticed something odd that Eric "O" did not address occurring during his "Power Braking" Technique to stress the V8 Engine that is worth mentioning at GMTN.

If you Watch & Listen to this Video once more from around 1:35 and then 6:00 and once more around 7:00 minutes along you can hear 3-4 rapid "Bump-Bump-Bump" events that should be of concern to the Owner, as the cause can originate from having a Broken or Damaged Transmission Mount.

When Stressed in Drive while raising the Engine RPM and with the Brakes applied, the entire Drive Train will try to Buckle from the Strength of the Rotational Torque being loaded along its length against the resisting Brakes and the constraints of the Motor and Transmission Mounts..

This action can often become strong enough to lift the Transmission right up off of any Loose or Damaged Transmission Mount with repeated 'elevation and dropping' events occurring as the result.

In some cases, even Bad Universal Joints on the Main Drive Shaft will raise an 'Ugly Face' here too and of course... these issues are fairly EZ2 Investigate using Ramps or NON-HF Truck Jack Stands and a Floor Jack to manipulate the Transmission. Having a Bright Flash Light and some Curiosity while "Fiddlin' Around" down there will surely help too.

No Offense or Criticism meant towards Eric "O"... Just Sayin'...
 
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