My fc3s constantly runs lean and idles very rough and when I put it into any gear if I don't keep giving gas it'll die out. Is it because of the apexi neo computer, should I go stand alone?

 

You'll need to post the settings on your NEO.
You may also want to check out the other sections of the Forum as they may be more specific as to what you have on your car( like the SAFC section)

Personally I see a lot of "What is going on with my car???"
when someone posts and says they have a SAFC on the car,It usually turns out to be the SAFC.
Stand alone?.you got a Turbo engine?..you did not state that,along with any other Mods.

 

As far as I know there are no settings on the apexi, yes I have turbo II s5 swap bone stock with even the stock turbo but it has a ATK sticker on it so it may be built I'm not entirely sure upgraded koyo radiator and that's about it

 

no settings on the neo if you all stock you dont need it but yes it could be a issue it bypasses you ecu for your fuel map

 

That Neo needs to see the AFM set to flapper and also the tps setting does it not?

as I said,not familiar with it as I read too much crap about them,and that steered me away from them.
The Super AFC section would have more info.
Link:

 

I looked through and I'm not getting the answers I need, on idle it begins to run super lean..afr will be at 13 then start jumping to 17+ I can't seem to get the car to idle right

 

I may get flamed here, but I hunted around everywhere here for an idle issue and tried the throttle position sensor, the bac solenoid, etc to get my idle from bouncing. the problem I had with my s5 tii was that the check valves for all 4 oil injectors were blown out. it wasn't a problem until the engine warmed up and the oil started flowing well. when the rotors closed, it would force oil and fuel back up into the throttle body and then back down into the engine. This made a 'closed-circuit' vacuum leak... or that's the best description I can think of. It has lean cycles and rich cycles. The way I found it out was there was fuel and oil clear up to the butterfly valves on the throttle body.

The first indicator should be to pull the top plenum and see if it smells like fuel. The tubes should be moist too. if so, that might be your problem. Mine was obnoxious at anything below 3k rpm. The injectors on these engines are as old as I am so its probably due to be changed. They don't go out very often, but if its bouncing, that could be it. Somebody will probably call me a fool for this but its what was my problem. If they are not new, might as well replace all of them anyway.

Im not as knowledgeable as the senior members here, but I know what I did to fix a fuel/idle bounce issue. Good luck