I have an RB20 with an HKS GT2530 turbo. With the Boost controller removed, the actuator pressure was approx 0.8bar but recently it started hoovering there until 4k rpm and then started climbing again and wouldn't stop (1.3bar+). I fitted a new HKS actuator and new vac hose (actuator to inlet pipe). Now the boost just climbs progressively but still doesn't stop! I tried winding the rod out so it holds the wastegate slightly open to start and still made no difference. Surely you dont want the wastegate open at all at idle, and shortening the rod will only make it want to boost higher? My AFR readings dont suggest an air leak anywhere, but it would need to be in the actuator hose to effect that anyway? Wastegate arm on top of the turbo moves freely too. Any advice would be appreciated.
Is this turbo a real GT2530? The ebay ones have very small wastegate ports and can't control boost beyond a certain load point. I can't remember how these internal gate diapghrams work but idle vacuum might hold it closes as well. An open wastegate anything before desired boost will increase the spool time. I am guessing you don't have the vacuum line run properly based, re-check the lines. The wastegate line should run from the WG to the turbo housing IIRC. Also you have a maf sensor so your fuel is adjusted based on the air the MAF sensor is seeing until you hit load cut / boost cut with the ECU. Would happen to me at 14.5psi on factory ECU / cold night.
Thanks for the reply. Turbo is genuine as far as I know but it came on the car. Everything was working spot on until a week or so ago so something has changed. Its a nistune ECU and the car is mapped for 1.2bar and normally uses a blitz EBC to achieve this. I agree the problem seems to be air getting to the actuator, but its only a short vac hose running of the inlet and that system has worked fine up until now. Unsure how else it could be routed?
Update: I ran the actuator pipe from a union on the inlet mani with a different pipe, so it's definitely getting the same pressure as my boost gauge, still same problem. I used a screwdriver to push the wastegate arm with actuator attached and it seems to move smoothly with good actuator resistance. I also removed actuator and drove the car, and it made no boost so the wastegate isn't blocked/stuck shut. The actuator mount also has minimal flex in it. Any ideas!?
