Okay, I'm not exactly sure if this belongs here but it does involve my car going single so I'll put it here for now and if a mod moves it then so be it.

Recently my car has been idling low and sometimes stalling out when the fans come on and I have no idea why. When I first got the car back from KD it did alright except for being terrible about fouling the plugs but I anticipated that happening until I got the car tuned. Then after I put around 3k miles on the engine I started to push it a little while it was still on the basemap that KDR put on the Microtech. Nothing extreme just 10psi. But then sometime after that the car started idling low and the vaccuum was erratic I can't figure it out. You can adjust the idle screw and it will be fine for a short time and then it starts all over again. I finally noticed that this only happened when the fans came on.

So I'm puzzled with it. When the fans are off the idle and vaccuum are fine but when they come on it drops to about 600-700rpm and then vaccuum drops to around -11 to -9. Even then, the car is otherwise fine, it boosts fine and there's no noticeable loss of power.

Has this happened to anyone else before? I'm thinking it might be a vaccuum leak or since its only when the fans come on, an ECU problem. My car still isn't tuned yet so hopefully it would be something simple with it but I know these cars are anything but simple. I'm just praying I haven't hurt my new engine.

Any help is greatly appreciated.

 

I'm using an AEM and getting the same exact symptom as you are. I believe it has something to do with the current draw hitting the limit of the stock alternator at idle. Still working on investigating this.