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'07 Cobalt LS, 2.2 L I-4

Car is not getting a misfire code. (p030x) However, the mode 6 data shows Non-zero "misfire counts" on all cylinders. The counts are single- or double-digits, and are very low at highway speed. I don't feel any misfires, and I'm not aware of a performance problem.

  1. Should these counts be just dead-nuts 0?
  2. Is misfire detection reliable at high speed?
Pᴀᴜʟsᴛᴇʀ2
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George
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1 Answers1

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You're raised two questions:

Should these counts be just dead-nuts 0?

In my experience, NO. While I'm sure every manufacturer has their own standard for when to set the CEL on a misfire, some number of misfires are "normal".

Is misfire detection reliable at high speed?

The speed of an automobile engine compared to the speed of the electronics monitoring and controlling it are at least an order of magnitude apart. So yes, even at the engine speeds used in F1 engines (~20K RPM) misfire is detected and controlled.

jwh20
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