DIY Fix: How to Install a Greddy Boost Cut Controller (BCC) on a 2JZ-GTE with VVT-i (Lexus GS300/Toyota Aristo)

A Greddy Boost Cut Controller (BCC) will allow you raise the boost pressure without hitting the factory boost cut.

Our project Lexus GS300 (Toyota Aristo) has been running great, and we love the flexibility of the VVT-i 2JZ-GTE engine around town.  Boost comes online at 1500 rpm in sequential operation to provide adequate torque, and the 2nd turbo comes on at about 4200 rpm to provide additional power up top when needed.  We switched the car to a parallel setup aka True Twin Conversion (TTC mode), which has a bit more lag with the turbos providing boost starting at about 2800 rpm, but there is no dip in power between 3800-4200 rpm when the 2nd turbo would spool up in sequential mode.  This gives the car a more linear feeling powerband with more midrange punch, albeit at the expense of low end torque. 

We recently installed a bleed valve style manual boost controller to increase the boost from the factory setting of 12 psi.  One thing we noticed with the installation of the boost controller was the immediate increase in low end torque.  Noticeable boost (~5 psi) would come in at about 2200-2400 rpm depending on the gear we were in, which made our GS300 much easier to drive around town at low speeds.  We wanted to set our boost to 16 psi, however we were running into boost cut at 14.7 psi (1 Bar) of boost.  Boost cut is a safety feature where the computer cuts the ignition to the motor if the manifold pressure exceeds a certain threshold (1 Bar in our case with the 2JZ-GTE engine) for more than a second or two. 

To bypass the factory boost cut, we went with Greddy's Boost Cut Controller (BCC).  This device caps the voltage signal coming from the manifold pressure sensor, so the car's computer will not invoke boost cut.  Since Greddy does not make a 2JZ-GTE specific BCC, you will need to source one for a 2nd generation MR2 (SW20 chassis).  Follow along as we show you how to install the BCC on a Lexus GS300/Toyota Aristo 2JZ-GTE VVT-i engine.