Quote Originally Posted by Nigel Pitsch View Post
Just a thought
What size inj are you using , Ive heard of some using way oversize inj than what is req ,,so then the idle area is in the non linear zone leading to a nasty idle..
I also had a surge at highway cruze speeds IE low ish throttle openings eventually I fixed it by changing the way the surge valve worked I added an arm to the shaft and fitted a spring to load the valve open , In my case as im using a bigger centrifugal SC and its out of its happy zone at low ish rpms so it became necessary to allow more bleed of in these zones
Got zero surge now and clean map graps runs well
This was all related to disabling the VVT function in HPtuners. If I set to disable, the vehicle had all sorts of issues. Turning it back on, setting the parameters to enter VVT operation to point it would never reach and disabling codes fixed it.