PID's

Can anyone Explain PIDs to me, I've heard and seen the term several times but don't know what exactly a PID is. from what I can see, it is an operating instruction of sorts, is that accurate?

Thanks-

Eric

well, in the OBD2 world, i've been under the assumption of Parameter ID....

in a more general sense, specifically math: Proportional, Integral, Derivative.

OBD-II PIDs (On-board diagnostics Parameter IDs) are codes used to request data from a vehicle, used as a diagnostic tool.

http://en.wikipedia.org/wiki/OBD-II_PIDs

so then the pids define what information the PCM receives, and how it uses the info?

PID: P=Proportional I=Integral D=Derivative. Bottom line, PIDs provide a way to hold a process to a set-point, like your AC thermostat; or to control events gradually so that a change from one state to the next is not made all at once. For example, if you accelerate from 1000 to 5000 RPM and immediately let your foot off the gas so TPS% = 0, the IAC will not immediately go to idle setting, but rather will gradually go there (note that gradually here is in a period of milliseconds). Here are two good explanations:
http://www.expertune.com/tutor.aspx and
http://www.eetimes.com/document.asp?...&page_number=2

Edit: The PIDs are within the code of the bin to control events.