Joe P MBC Adjustment

[X-Rated GST]

I got a question for you guys...i just finished installing the MBC but i can't get the setting right. I know counter-clockwise = less boost and clockwise = more boost. I go and do 3rd gear pulls (it's what the instructions suggested) and the gauge would go up to 14 psi and hold for a blink of an eye and then back down to 11 where it wouldn't even budge. Before the MBC install, it would do the same thing except it would hit 13 psi. I haven't tried adjusting the MBC anymore just to get everyone's input. I installed it according to Joe P's instructions one hose to wastegate(side outlet) and then to the nipple on turbo housing (one on bottom).

I was searching the posts and found a diagram that shows the install differently.

My current mods are Ebay air filter and turbo intake, UICP and 1G Bov. Should i try to install the MBC to the diagram above? I need some input from you guys, thanks.

 

[Bigglesworth87]

The diagram is correct, it seems that yours is installed incorrectly. Double check your connection to this one that you have pictured.

 

[Bigglesworth87]

I used this link to help me install my boost controller also!

http://www.belitski.com/vfaqhallman.html

 

[zippyshoe]

You may just be seeing the normal response of the stock 2g turbo. If you are seeing a decrease in your boost pressure as your RPMs approach redline, then you are probably seeing an expected limitation of the stock 2g turbo. Typically the T-25 is incapable of maintaining 14psi boost pressure all the way to redline - the boost pressure tends to drop to about 11 or 12 psi near redline no matter what you do with the boost controller.

 

[X-Rated GST]

Gosh damnit, i knew it.

It's weird, the instructions from joe p. told me a different way. Oh well, i give installation diagram a try and see how it goes.

I've searched a lot about this topic, and i've found some people that installed it the way i did and some the way the diagram shows, why's that?

 

[zippyshoe]

It sounds like the only difference between the way you connected your boost controller vs the way it is shown in the diagram is that you used the nipple on your turbo compressor housing as your boost source while the diagram uses the hose going to the BOV as the boost source - either method should work. However, some people (including myself) prefer to connect the boost controller the way you did - using the nipple on the turbo compressor housing as your boost source. This will tend to minimize any boost spike you may see.

 

[wongcfoo]

It sounds like the only difference between the way you connected your boost controller vs the way it is shown in the diagram is that you used the nipple on your turbo compressor housing as your boost source while the diagram uses the hose going to the BOV as the boost source - either method should work. However, some people (including myself) prefer to connect the boost controller the way you did - using the nipple on the turbo compressor housing as your boost source. This will tend to minimize any boost spike you may see.

It's weird, when i connected the controller to the nipple on the turbo, the boost gauge would shoot up and then fall back down, is that considered a boost spike?

 

[zippyshoe]

Boost spike describes the situation in which, when you are building boost, the boost pressure briefly overshoots the boost pressure that you have set your boost controller to. For example, lets say you set your boost controller to 14 psi. While you are initially building boost, you see that your boost pressure quickly rises but does not immediately stop at 14 psi. You may see your boost continue to rise above this point to say 16 psi. Then, your boost pressure quickly falls back to 14 psi and holds there. This would be an example of a 2 psi boost spike. Boost spike is caused by the small time delay needed for your boost controller to "sense" a rapid change in boost pressure as well as for the wastegate actuator to respond to the boost controller and open the wastegate. You want this time delay to be as short as possible in order to minimize boost spike. Hope this helps!