Cylinder 5 Misfire Still Present?

2007 LINCOLN MKZ
150,000 MILES • 3.5L • AUTOMATIC
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FREERIDER78
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Cylinder 5 misfires. I did a coil swap to determine it's still cylinder 5. When I did the injector pulse test on this cylinder the noid light flashed a few times and then stopped, indicating a problem with the injector circuit but not the injector. Could this be the ECM stopping the signal?
Jun 28, 2026 at 12:45 PM
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STRAILER
  • ✓ASE Certified Mechanic
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Yep, it sure can, injector drivers go bad all the time inside the PCM. Fortunately I believe you can swap out the PCM without programming for this year, I would get a used one from eBay. Let me know how it goes.
Jun 28, 2026 at 5:47 PM
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FREERIDER78
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Would this be your chosen direction or are there more tests you would conduct?
Jun 29, 2026 at 11:26 AM
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STRAILER
  • ✓ASE Certified Mechanic
  • 54,832 POSTS
  • ASE Certified Mechanic
You may want to check the wiring and the condition of the pigtail @ the injector if they are okay the PCM is next. Here is a guide to help and the wiring diagrams so well.

https://www.2carpros.com/articles/how-to-check-wiring/

Check out the images (below). Please let me know what happens.
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Jun 29, 2026 at 2:12 PM
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