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Slight Backfiring and Mode 6 misfire


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I'm entering two posts that are sort of related I think.


I was hoping people would tell me their experience to know if I have an issue.


I'm fairly experienced with Auto Diagnostics, but I don't know the normal behavior for a GT500.


Here are the parameters to my question:

  • the CEL is NOT illuminated
  • Sitting at idle
  • Car warmed up in closed loop
  • I snap the throttle
  • I sometimes get a slight small back-fire
  • When this happens, in mode 6, "Misfires for Current Cycle", on differing cylinders, increments its Value parameter
  • Yet, misfires in the "last 10 drive cycles and manufacture specific test" has value of 0 and result set as passed
  • I've attached one such Scanner screen capture
  • I unfortunately have not had a chance to view STFT and LTFT
  • At idle, I cannot feel or hear a misfire. This only occurs on a snap. The car does not hesitate when accelerating normal or hammering it. It feels strong; you know like a Cobra should.


So, if you don't know anything of what I just said, you can still help me. When your car is warm at idle, snap the throttle, does your Cobra slightly back-fire?




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