RB26dett ITB and vaccumm question

[sr20tom]

I know this sounds stupid, but i am having trouble with my map sensors on the power FC. They are always reading a + pressure. Now would the ITB effect the pressure in the manifld or do i need to plumb it from the little nipple behind the itbs. i guess this can be compared to a regular car where we have pressure on the charge pipe and pressure inside the manifold after the throttly body. In other words is it the same pressure before the throttle bodies as it is after the throttle bodies? Thanx

[Cjmartz2k]

The sensors need to read the area between the ITB's and the head. Think of it this way. The restriction caused by the throttle body(s) is what makes the vacuum, but boost is everywhere (when you have it.)

[gawdzilla]

where are you putting the map sensor? here's a hint.. the intake manifold is not a vacuum source

[mcfly]

I know this sounds stupid, but i am having trouble with my map sensors on the power FC. They are always reading a + pressure. Now would the ITB effect the pressure in the manifld or do i need to plumb it from the little nipple behind the itbs. i guess this can be compared to a regular car where we have pressure on the charge pipe and pressure inside the manifold after the throttly body. In other words is it the same pressure before the throttle bodies as it is after the throttle bodies? Thanx

Apexi said to install the map sensors in the 3rd and 4th throttle body after the butterfly. it has become the general consensus though that you can use the balance tube running above the throttle bodies. This was will give you a stronger vacuum reading as the throttle body mounting often causes fluctuations on light throttle.

[sr20tom]

There is this ballance tube that you are talking about? I only work on the car on the weekends so i cannot visualize the tube. i do know that there are little nipples on top of the itbs themselves and I need a lot of vaccum sources for this car. I am trying not to use a 1000 t's for this. Here is a pic i found on google.

I need a lot of vaccum for this car. 1. Fuel pressure regulator2. BOV3.2 map sensors 4.AEM Tru Boost gauge 5.There is some square box in the driverside cornere that needs vaccum and i dont know what it does (RHD R33)

Other Side Of The Motor

1. Tru Boost Solenoid 2. 2 Wastegates ( 1 Line From Tru Boost and another I guess i have to tap into the hot pipe or the turbo bousing)

Where can I get these sources from without using 1000 t's. Are those 3 nipples on top of the ITB's my only true source of vaccumm?All your help is much appretiated. Thanx Tom

[sr20tom]

I forgot to tell you guys that its a single turbo and I eliminated the hard lines of water and vaccumm that run begind the motor to the exhaust side.

[l0nestar]

No. That is not a balance tube.

The I don't have any pictures of the ITB setup I had before I sold it. The balance tube goes under the throttle-body assemblies. It is in the FSM in an exploded view. I will look for a picture..

[sr20tom]

Here is a pic i found on-line. Are the nipples coming out the balance tube? As far as my understanding goes, the vaccum to the chole block is supllied from the intake manifld again not giving me a negative pressure????

[Cjmartz2k]

No, that's the IAC valve. The balance tube is on the top and has vacuum ports at either end (front and back). I looks kinda like a fuel rail.

[Cjmartz2k]

Look between the fuel rail and the valve cover in this pic. See the aluminium rail? Follow it to the front. See the metal mesh vacuum tube going into it? That's where you want to go.