2G 97 tsi doesn't want to idle randomly

[blazerlt]

750cc injectors, 255 fuel pump, Aeromotive fuel pressure regulator, 16g @ 20psi, 3' turboback, ecmlink v3.

The car runs flawlessly besides this one hiccup. It normally idles around 14.5-15.0 but it will randomly start to lean out and reads --- or just very lean like 17+. if I let it sit like that it eventually returns back to normal. what could it be? Is it the tune? Sensors? Vacuum leaks? Any help at all would be much appreciated.

 

[portum89]

Mine does that, I just dont pay much attention to it anymore, doesnt bother me anymore, no clue what it could be. Not the tune, maybe something puts a lil load in the engine or something leans it out vacuum related maybe.

 

[secretagentstv]

It could be your radiator fan turning on. It will lean it out for a second and climb back up when it shuts off.

 

[blazerlt]

It could be your radiator fan turning on. It will lean it out for a second and climb back up when it shuts off.

If it didn't do it on coldstarts too sometimes then id think it was that. Is it hard on the motor letting in lean out at idle like that?