98 GTB Twin turbo Boost Solinoid......

[rfrbwags]

Hi all. I have read bits and pieces all over the place about replacing or refurbishing the factory
boost solinoid which i hear gets overlooked when it comes to servicing and can affect the way
your car performs in a HUGE way.
Im in Nelson,New Zealand and am wondering if anyone can tell me how to refurb the unit if possible
or whether replacing it is neccessary,and where to get it from? Obviously i want the best performance possible from
my ride and any help would be appreciated. :smt023

[Robbks]

ok here's the best way to make a TT run properly.

Convert it to single turbo...

Or if you're a glutton for punishment and want to keep it TT then do the following.

-remove each and every vacuum line (one at a time is best) from both inside and outside the BBoD (Black Box of Death, aka Solenoid box) and clean it out with some upper-engine cleaner (from subaru) or throttle body cleaner.
-replace any cracked/ perished/ split vacuum lines with new ones
-take when replacing lines that they do not have restrictors in them. Line #2 (pressure feed for Positive pressure side of ECV has one) and the line to the primary wastegate has one also.
-next, remove the solenoids themselves from the BBoD and clean them out aswell, including the vent caps
-also clean the wastegate solenoid which is in the passenger side guard
-check all vacuum actuators that they operate correctly and will hold a vacuum (use a piece of clean tubing and suck/ blow through it, they should operate correctly and smoothly)

there's a heap of porting you can do in the exhaust side of things to help reduce the VoD (changeover lag) such as porting the primary wastegate, up-pipes and especially enlarging the ECV port in the secondary up-pipe

here's a great document that helps explain what everything does.
http://www.veloce.pwp.blueyonder.co.uk/ ... opprt2.htm (http://www.veloce.pwp.blueyonder.co.uk/Twin%20Turbo%20Operation/ttopprt2.htm)

i also suggest bypassing the factory boost control and using a good EBC
one that has the ability to keep the wastegate completely shut below a certain boost level, this can help to reduce the VoD a little aswell, and make boost faster

Also, a less restrictive exhaust gives very good gains in low-mid range response aswell

2.5" dump from the primary (with divorced wastegate pipe)
3" dump from the secondary
into a 3" system with free-flowing mufflers

[kevinjones]

Most of these cars are growing after 10 years now, and all rubber parts most likely to succumb to time and perish / deform due to stresses like heat, pressure and bushings are replaced after tension.Suspension X miles, which is followed on the engine. Apparently, the manual version has a stiffer chassis / stronger weld, as you would not notice it visually, but it would feel different dynamic.