idle surging?

[Brunoboy]

Biss screw all the way in, new o ring, it didnt do this before I changed the ecu and link and pump, I bought a brand new ISC as well, now it surges when cold and warm. Causes? Can I stop it in Link?
-Shane

 

[GVR4_1057]

Are you using simulate idle switch in link? That may help.
Also maybe do a boost leak test.

 

[Brunoboy]

It never uaed to do this, and the only things changed are the isc ecu link and rewire, the simulate was on and it didnt make a difference , the other thing tht helped was the groundig option, but still with the biss all the way in it idle surges

 

[fuel]

the biss screw is only one of three valves which controls the idle speed - it's basically a fine tuning adjuster. I would make sure the throttle plate and surrounding area where it sits when closed inside the throttle body is nice and clean and free from deposits blocking it up - the throttle plate is meant to be every so slightly open when it's in the closed position. The throttle stop screw should be adjusted a little bit passed the point where the throttle plate starts to bind as you're trying to gently open the throttle plate immediately after opening the throttle and letting the return spring slam it shut - once you're satisfied with the throttle plate being in the correct spot when fully closed then move onto adjusting the TPS and idle switch (should be a faq somewhere on the forum), and then after that the biss screw should be adjusted - ideally it should be about half way when the engine is warm and idling at approx 750-800rpm.