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When diagnosing diesel noise I found that cylinder 2's COP's internal spring was stretched out and allow the internal rod to move more than normal.
comparing good (left) to stretched out (right)
To troubleshoot I swapped spark plugs between cylinders, replaced COP, and the issue continues on cylinder 2 by stretching another COP.
Truck had a misfire when I bought truck in cylinder 2. new spark plug and COP fixed that but in turn caused the catalytic converter to fail and was replaced by dealer.
Besides noise see no ill effects on engine or performance. Did noticed on Edge that my Avg MPG dropped pretty quickly which idling at a light. 2-3 minutes at a light dropped 1-1.5 MPG.
Has anyone ever seen this happen before?
Thoughts are compression issue or fuel injector issue.
I've already replaced the cop twice and both times within 50 miles of driving the noise returns because it had stretched out the spring. I don't believe the issue with the brand of cop but more the cylinder.
You are incorrect, stretching the spring is common among Mustang owners and Mazda owners. That is not your problem. A stretched spring is not the cause of your issue. http://www.mazdaspeedforums.org/foru...etch-mod-4577/
You have something else going on. My best "guess" is you have an injector problem. If you say you had a catalytic converter melt down, then the issue is with your injector, most likely on #2.
COP issues
