How to test a knock sensor - GM (low power condition)

GM 3100 engine, knock sensor test.
This engine had a slight rod knock or upper engine noise that was causing the knock sensor to record a false signal. The computers reaction was to retard ignition timing in an attempt to quiet the knock sensor down. The result was a severe low power condition at times.
The main take away with this case study is for low power complaints, don't forget to look at your knock sensor activity as a possible cause.

Engine Performance Diagnostics chapter 10 pages 6-7

Symptoms
intermittent low power
runs good cold and at WOT
knock retard degrees on scan data goes very negative

Fix
internal engine noise was causing false knock sensor activity
left knock sensor disconnected (car was not worth repair cost to fix the engine)

Tests shown
how to test a knock sensor
how to determine the cause of a low power condition

Tools used
scan tool
labscope
back-probing tools

Playlist
(Chapters 9, 10 and 11) The 5v Reference and Signal Circuit Quick Tests
   • (Chapters 9, 10 and 11) The 5v Reference a...  

Related Videos
How to test a Knock Sensor (P0328) - Subaru
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How to test a Knock Sensor (P0328) - Nissan

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