I think the rev3 system is different from the rev2.
The rev2 system has butterflys inside the inlet manafold that open,close as needed by the ecu you disconnect this when you fit a mbc,ebc.
Hey Ricky, that is called TVIS (Toyota Variable Induction System) and yes it only came on genI & II 3sgte. It was also fitted on the 4age and possibly others?. Toyota introduced it as a measure to create more torque in low rpm bands. This was as a result of their moving to multivalve heads (16valve rather than 8 in a 4 cyl).
The increased volume of available induction moved the efficiency band of the engines higher up the rev range, i.e. they breathed a lot better up top but with some loss of low down torque due to a reduction in the port intake velocity. The idea for TVIS then is that at low down RPM's the system actuates a butterfly in 4 of the intake ports to effectively reduce the size of the intake port and therefore speed up the intake velocity. Then when it get's to a preset RPM, the ECU would open the ports allowing the full charge. The TVIS plate is located between the inlet manifold and the head, but it's not affected by changing to a mbc or ebc.
I used to have a Yamaha FZR250RR it had a similar system but on the exhaust (called EXUP) whereby a valve in the exhaust would be partially closed at low rpm - causing greater backpressure and extra torque, and then it would open fully at a preset rpm, allowing my little 250 to rev out to 16,000rpm
- yes no joke!
The other system you guys are talking about is TVSV (Turbo Vacuum Solenoid Valve). Basically what happens is that as your manifold pressure builds (i.e. boost), your turbo syphons off some of this pressure to the wastegate, a device which bleeds exhaust pressure from the hot side of your turbo. This is a control mechanism for your turbo to protect your engine. The wastegate has an internal spring (I guess it is .5bar or whatever the lowest Toyota pressure setting is) that governs the pressure that the turbo can spool to. Because Toyota wants to have the ability to run multiple pressures (i.e. high and low boost mode) then they have a vacuum solenoid that intercepts the pressure feed between the turbo and the wastegate actuator. This is what the TVSV is. As I understand it the factory ECU offers low boost in 1st & 2nd, and also when in limp mode (i.e. excessive knock or over boost). If you're getting low boost in high gears then it is possibly a boost leak somewhere or maybe problem with the wastegate or bov.
When fitting a manual boost controller or electronic boost controller it is typical to remove the TVSV from the boost circuit.