This site contains car modification and auto upgrade information specifically for the turbo import Toyota JZX90 MarkII TourerV, however the principles applied here can be mostly utilised regardless of the make or model of motor vehicle.
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Apexi AVCR Boost Controller 14/2/2004
Stock boost on the JZX90 is somewher around the 7-8 psi mark which is nice and conservative for the ceramic turbos. After some intake and exhaust mods this can naturally raise the boost levels to 10-12 psi, and I have heard that sometimes it can raise as high as 14 or 15psi which is where boost cut is hit. This is also dangerous for the ceramic turbos as this is the point where they decide that enough is enough and they vacate the compressor housings and take a trip down the dump pipe. Inevitably the Catalytic convertor acts as border patrol to freedom and sometimes the cat gets abused by these freedom-seeking turbines.
I did not want this to happen until I was completely ready for a turbo upgrade, so in order to control the boost level accurately and prevent overboosting in the future, I invested in an Apexi AVCR electronic boost controller. The consists of a nice vacuum fluorescent blue screen display unit, some wiring, a solenoid valve, a pressure sensor with filter, and some rubber piping with fittings.
The first step was to find a location for the solenoid valve. Ideally the solenoid valve should be placed as close as possible to the wastegate actuators, however there are two things that stop this from happening. Firstly the turbos get very hot and as much as this solenoid valve is very sturdy, close proximity to a glowing turbine housing will only lead to premature failure of the valve. Secondly there are two wastegate actuators with the twin turbos and they are about as far away from each other as they could be.
So I decided that a position somewhere in between the turbos but far
enough away from direct heat would be best accomplished by mounting on
the upper side of the chassis rail.
So the intake pipe is removed, along with the airbox. The silicone hose between the turbo outlet and the intercooler is also removed at this stage. This is where I am up to in the first picture.
The wastegate actuators need to be located so we can determine a good central position for the solenoid. The nipple for the rubber hose is easy to find on the front actuator as can be seen in this shot.
The rear turbo however is very difficult to get at. The wastegate actuator nipple is tucked away in a very inconvenient spot as you can see here. It was at this point that elastogirl would have come in handy, however I had to work with my big hands and arms so it was a little difficult.
This picture shows the rear wastegate actuator and just obscured on the
left is the actuator nipple.
Now the boost control solenoid is screwed down onto the chassis rail. The placement is not really in the centre of the two turbos, it is closer to the front turbo, but considering there was a significant distance to go to either turbo I figured it would not matter too much.
The solenoid has one input nipple and one output nipple and basically runs a duty cycle controlled by the head unit to open and close a valve in between these two nipples. One nipple takes the intake air charge pressure, while the second nipple connects to the wastegate actuator. Simple on a single turbo car, and only slightly more complicated on a twin turbo car.
On a twin turbo car each of the air lines need to be split into two and run to the appropriate places on each turbo. The reason the wastegate actuator line is split is obvious as we need to control both turbos. The reason the boost line is split is so that we are reading the boost level close to each actual turbo that we are controlling. If there is a slight variation in boost between the two turbos, this arrangement will give us an average value.
The solenoid valve seems to be placed reasonalby well for the two t-pieces to be fitted just above it, and provides a reasonably short enough distance to where the hoses need to go. From memory, the hose that leaves the bottom of the solenoid in the picture branches and attaches to each of the nipples on the turbo outlet in order to access the turbo outlet pressure. The hose leaving the left of the solenoid branches and goes to each of the wastegate actuators.
The AVCR also comes with its own boost sensor which needs to be fitted onto the intake manifold somewhere. It has its own cute little air filter that is attached in line between the intake manifold and the pressure sensor. This shot shows where I tapped into an existing hose with a t-piece in order to read the manifold pressure. The other end connects to the sensor itself.
You can see the small white disc-shaped item in the picture here which is the filter.
The black item between the diagnosis plug and the filter is the pressure sensor. It is mounted on to side of the the suspension tower, held in by two bolts.
Finishing the job then requires running the wires from the pressure sensor back to the head unit. And also running the wirees from the solenoid valve back to the head unit.
Now it is a matter of tuning the AVCR to provide the target boost with minimal overshooting and instability. This is beyond the scope of this basic installation but I may cover this in future.
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RECENT MODS CHRONOLOGY
5-Jan-2007
Turbo pages and Headlights
I have recently added a new page about my single turbo conversion. There is a second page yet to come, but page one outlines some of the supporting components needed as well as the turbo itself.
Page 2 will be forthcoming where I detail the fitment of the turbo, manifold and wastegate.
I have also added a page for modifications to my headlights that should be very useful for owners of import vehicles.
25-Jan-2007
Site Revamp
Wow, it has been a very long time since I worked on the site, but now I
am in the process of redesigning it so stay tuned as I add some more content
and attempt to bring this project up to date.
18-Mar-2006
Car Changes
Lots has happened since my last update on upgrades to the car. For instance
the car is now running a 2JZ bottom end and the gearbox has been completely
rebuilt with a stage 1.5 shift kit, beefier clutches and a 2800 rpm stall convertor.
To say that this has transformed the car is an understatement. The car is now
torque heaven, and is an absolute pleasure to drive. The lag that was sadly
felt with the 2.5L motor is now completely gone with the 3L and the stally.
When I can find time to update the site with the process I went through I will
do so. I have many hundreds of pictures to add.
Whatever your vehicle is, whether it is a turbo car or NA or a Toyota or other manufacturer, I hope that the automotive information on this page is of benefit to you as you take the path of modification and upgrade on your car.
Toyota JZX90 MarkII TourerV.