Hi guys. Im hoping you can help. I've just about to buy a Gen3 Twin Turbo Efini (Jap spec) and the 1st Turbo seems to be releasing its boost to early. Was thinking the diaphram in the dump valve could be split but does anyone else have any ideas?

Once the second turbo cuts in shes fine and shes off like a rocket!

 

What mods done to the car? Sometimes changes like exhaust and intake on an otherwise stock car can throw off the boost pattern. It could be the restrictor pill for the pre-control actuator is either missing or no longer the correct size. If thats the case you may be able to resolve the problem with a bleeder valve inserted into the pre-control line.

 

I think it has an HKS cat back exhaust and thats it. Would that throw it off? Or would it be only if it was doubled with a front pipe/de-cat. This restrictor pill-does it act as an airflow/vacum reducer? Also where would i find the pre-control line? Is it possible a vac hose has just popped off? Sorry for all the questions i'm a complete noob if you hadnt already guessed! Lol Cheers man.

 

With just a cat-back exhaust I wouldn't think your boost pattern would be thrown that far off. So it could be a restrictor pill in the pre-control line. To replace that with a bleeder valve check this out:

http://robrobinette.com/boost_controller.htm

If you go this route be very careful.If you adjust the pre-control improperly you can get a big spike at the transition and blow things up.