This is wierd, car idles fine until i turn the A/C on. It goes from 1300k down to like 400k up and down until i take off or turn off the A/C. Why? Basic S3 mods, still need to dump ZZP can tune for custom tune but what the hell is causing this?

 

normal. drag of the compressor. Better question is why does your car usually idle at 1300?

 

even better yet.... why does it idle at 1,300,000 (1300k)?!?!?!? These those new neutral balance shafts I've heard so much about????

 

His RPMs probably shoot up to that much when he has the A/C on then surges from there down to 400 repeating.
Mine does this sometimes, but if its constantly doing it, try cleaning the throttle body.

 

Gella is right, it shoots up to 1300 then down to 400 and up and down. My normal idle is around 950 or so. I have cleaned my tb when i did the s3 mods about 4k miles ago. And also it does this similar up/down idle at warm up, it does this until normal opperating temp then smoothes out. Its not as drastic as the ac but its annoying, around 600 to 1200 rpm

 

That's cat warmup circuit. You have have that removed with a tune if it bothers you.

 

surely just the cat warm up isnt causing the A/C idle? i can see the car warm up/cat warm up.

 

IF the TB,SC inlet, and MAF are clean without any buildup, sounds like a problem with the tune to me

 

No. You described two different things, I gave you two different answers, one for each item.

This is cat warmup. As you said, it goes within 1 to 2 minutes. It can be removed by a tuner and is not related to rough idle with the AC on.

 

well it didnt do this before the S3 stuff and tune. oh well i guess its just an annoyance i gotta live with

 

I have the same problem, as far as ive been told, its the tune, I have a custom tune, and i still have the issue, so good luck lol

 

I have the same problem, as far as ive been told, its the tune, I have a custom tune, and i still have the issue, so good luck lol