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Boost Controller Install


VolvoWill

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I am having trouble installing my boost controller. I know that it is an easy thing. I think that I must be doing someting wrong. I looked at the directions in the modifications section. I have the boost controller hooked up with the bottom hose going to the inlet of the BC and I have the other hose going from the outlet to the wastegate down by the turbo. I unplugged the BCS and capped the ends off like the directions said. I am just looking to run about 14-15 psi right now. If you know what I have dont wrong please help and pictures would be greatly appreciated. I have a Forge Motorsports MBC.

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d3ubcslines.jpg

Use the green and yellow hoses in the illustration. The blue hose in the illustration goes to your intake pipe. Disconnect that and plug the intake side, or you won't get much boost (like 6psi max I think). The 'green' (off of the turbo) hose is your 'in' and your 'yellow' (off of the wastegate) hose is your 'out' on your mbc, regardless of what you're using.

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So what your BC does, is that it controls the pressure which is put on the wastegate.

It does so by altering the compressor housing pressure (coming thru green line) down by bleeding into the atmosphere (or blue hose).

On an electronic BC (same for the orig BC) this is done using the so called ratio, so a ratio of 75 would mean that in 75% of the time the Wastegate membrane is connected to the atmosphere and 25% of the time to the comp housing.

The resulting pressure on the wastegate results in certain opening for the exhaust gases to bypass the turbine. Therefore your overall boost pressure can be regulated down to the desired level. (e.g. i get 1.35 bar with a ration of 75).

An MBC basically does the very same thing, just that its static.

In the old turbo days before there were BCS's, it was different.

In our picture:

if the green line is hooked up directly to your wasgate i.e. connecting compressor housing and wastegate direclty, wastegate should open at baseline pressure all the time. So when the compressor housing reaches a certain pressure e.g. 10 psi the spring of wastegate membrane gets compressed and the actuator lets the exhaust gasses flow.

Is that correct so far?

So, if the greenline gets disconnected, the wastegate doesnt operate at all?

I was always wondering if that would lead to an inevitable overboost situation/ capital engine damage?

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So, if the greenline gets disconnected, the wastegate doesnt operate at all?

I was always wondering if that would lead to an inevitable overboost situation/ capital engine damage?

yes, you are correct. This hose came off my car two summers ago, and I was overboosting (20+ psi). I took it into Volvo and they told me that the lower vacuum hose that connects to the turbo was the culprit. No engine damage was caused (afaik)

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So do you just cap off part number 16(the circle looking thing with all three hoses going into it)?

No. Remove the middle line, or remove that line from the intake pipe (underside of the pipe), and cap the line (and the hole in the intake hose if you removed it there). Forget about the stuff on the BCS, but don't unplug the wiring from it or you'll CEL.

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