A common problem on these second generation GM fuel injectors. (Multec 2) They would mechanically stick closed and cause an intermittent misfire. I cannot tell you how many of these I have run across, where the customer already replaced all of the ignition components in an attempt to fix the misfire. There are multiple ways to identify a no fuel misfire. In this video we will cover a few of them. In the related videos posted lower on the page, I will cover more.

Engine Performance Diagnostics chapter 17 page 20-23

symptoms 50

  • intermittent misfire
  • check engine light (P0300)

fix 50

  • clean or replace sticking fuel injector

test shown enh 50

  • injector sound test
  • secondary ignition waveform of a no fuel misfire
  • injector voltage waveform showing a missing pintle hump
  • misfire counters on a scan tool

Tools used

  • scan tool
  • lab scope
  • secondary capacitive pick-up
  • back-probing tool

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(Chapters 17, 18 and 19) Fuel Injector Testing

Related videos:

How to test a fuel injector (open winding case study) Nissan :


How to identify injector flow problems (Toyota 1.8L) part 1:


How to identify injector flow problems (Toyota 1.8L) part 2:


Secondary Ignition Waveforms (common faults):


Identifying type of misfire using tailpipe emissions:


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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.

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