i just bought a 2001 s2000 with 105k miles. the s2k was already modded by the last owner. it came with CAI, headers, exhuast ( really loud ) vtec controller, and others. i think i might have a few problems but it could be normal just want to make sure. i looked around the forum but had no luck

#1 when ac is on and leaving the car idle it would lose rpm and the car would shake for about a sec and the rpm would go back up again. it does that only when a/c is on and probably about every minute.

#2 when my throttle is about 1-2% ,according to the vtec controller, my car would shake and barely jerk back and forth kinda when driving, it sounds like it just could be the exhaust since the exhaust is pretty big and it might shake the car when the throttle is low. it does it when i take my foot off the throttle a lot also but stops once i apply break

#3 when driving the car has this weird sound, like its almost sound like its winding. it could be some type of turbine sound, the sound is hard to explain. its not that loud so i tune it out sometimes but it just bugs me to know if its a problem or not. idk if thats normal or not

#4 my air fuel meter shows lean stoich and rich and the meter would bounce back and forth all the time it rarely stays at one of them. is that normal?

sorry if these are all newb questions but i'm just a newly proud owner of an s2k and wanting to know more about what i have. thank you

 

i think 1 2 and 3 are pretty normal, since i have them too.

dont know about 4 though, since i dont have a air-fuel meter.

 

#1 - normal AC power issue
#2 - sounds like the car is bogging, which is normal when the accelerator is not pressed more fully when in too high of a gear
#3 - does it have an intake as well? Might want to check for an exhaust leak or header leak
#4 - can't help on that one.

 

#4 is ok. You want it to bounce back and forth. That means the Air/Fuel ratio is good. It will stay on one when hitting the throttle hard or right after you let go of the gas.