Discussion and questions related to the course EFI Tuning Fundamentals
what would be the cause or difference between a + reading and a - reading. which would be worse to see?
I don't understand your question. Can you tell us what engine, ECU, and/or software you are using? What does "+ reading" and "- reading" mean?
Do you mean a higher value on a particular channel or signal? If so, what is the channel/signal name in your software or documentation?
Are you measuring a voltage with voltmeter or oscilloscope?
the car is an 15 sti EJ25 on a cobb access port tuner. i am getting a -1.40 to -3.40 knock reading as a norm but from time to time i am getting a reading of .85 knock reading with no - and it is set as it is the high reading so i am assuming it would be considered a +
I don't have any experience with Cobb, and this page doesn't refer to any channel named just "knock":
It seems like what you might be describing is Feedback Knock Correction, or Feedback Knock Learning and if so, then those values represent the amount of timing adjustment. I would expect a negative number to be retarding timing, and a positive number to be advancing timing. it seems like large negative number would be of a concern.