Overboosting.

[Sparky206]

from all the reading i did, for people who have this problem, boring out the wastegate hole makes no difference

Im almost certain now it is caused by an overly rich tune

[ODessA]

i dont see how boost could go up 0.8 bar just cause of a rich tune, especially when its holding boost till almost 6k

i havent had time to touch the car during the week, i will get stuck into it on the weekend prolly replace the actuator and dump as i had planned on doing that anyway and let you guys know my findings.

i really appreciate everyones help here though thank you!!

[R31Nismoid]

imo, turbo off. dump off.

get it all in your hands and have a darn good look at movement with the dump on/off.

even paint the flapper to see its not touching anything.

then once its all ok, start measuring. find out how big the gate hole is etc.

then wire the gate open to max, and see what happens. if its still doing it, hole needs to be bigger. If its ok, connect actuator up.

if the problem comes back then the actuator is f**ked, or you failed off car checking of interference that's bout all it could be unless cam timing or something is way out perhaps.

[Pal]

I've had this problem for ages in my rb25. I have tried everything, different actuators, a high flowed turbo, a split and bellmouth dump pipe, but nothing stopped the creep. The only thing that i could find that made and difference was by placing a 2.5" restriction plate at the end of my 3" exhaust. That allowed the car to hold a steady boost level all the way to redline. I can't explain why, found the idea from a few supras who had the same problem. I have a feeling its to do with the tune, as im running stock ecu with mods, but when i get it re flashed i'll just up the boost anyway and let it do what it wants

mine was doing the same thing as well. used the restrictor plate till i got bigger injectors to let it run higher boost and a tune and the problem went away as well, i put mine in front of the cat. alot more variables to tune with if the ecu's just matched with the turbo. cats, injectors, exhaust , intercooler can all add up and put the tune out. i even bored out my wastegate from i think it was 24 mm to 28mm and didnt make the slightest difference.

[scotty nm35]

mine was doing the same thing as well. used the restrictor plate till i got bigger injectors to let it run higher boost and a tune and the problem went away as well, i put mine in front of the cat. alot more variables to tune with if the ecu's just matched with the turbo. cats, injectors, exhaust , intercooler can all add up and put the tune out. i even bored out my wastegate from i think it was 24 mm to 28mm and didnt make the slightest difference.

If all is well with the wastegate clearance you have another issue.

I agree, up the boost and the problem should disappear. The wastegate can only divert so much exhaust flow at that low a boost setting... Enlarging the hole may work, or weld an external wastegate in?