Hello again teener family....I was told long ago that the knob on the ECU should be turned all the way to the left and then turn to the right for 13 clicks....can someone please explain what the knob does and how to adjust it? Car runs great so I don't want to touch it before I know what I am doing. Any and all comments will be greatly appreciated.....thank you very much!!
gg

If car runs great.... Dont touch it!
Why poke the bear?

I get it but knowledge is power....in the 914 world you need to know as much as possible to keep things going....thank you for your reply.
gg

Have fun reading this.

https://members.rennlist.com/pbanders/

Idle fine tune only.
Your recollection is correct full L. is 0 value.
My understanding is that the stock setting is in the middle of its adj range but I dont recall if/where that is defined in any OE source.
Gross adjust idle value with the TB screw, then you can use the knob on later ECU to fine tune the idle, turning R. enriching the mixture.

PS - Brad is the MAN!

The knob is a fine tune on fuel mixture at idle. It has very little effect overall. MAP and CHT sensors have way more influence on how the car starts and runs under load than that knob.

That knob really is only to adjust CO for emissions purposes as measured with a tail pipe sniffer.

Click to view attachment

Having said that - no need to be moving it if your already running well.

There is the source.

As a general rule, I've found that turning it counter-clockwise until the idle starts to hunt (too lean) followed by then turning it clockwise 1-2 clicks to richen the mixture will put you in the ballpark of where it should be set. This assumes that the MPS is adjusted properly as well.

Curious @rjames - will this make a noticeable difference in how rich the exhaust will smell?

Maybe, depending on how much you adjust it, and the sensitivity of your nose.
It should be set using an O2 wideband sensor.