Stock Boost controller not working

[weaver]

I just upgraded to an EvoIII16G and got the mitsubishi dealer to install it along with some other things. I included a MBC but they didn't put it on because they said the stock controller held it at 10psi, which was fine untill I do some other mods. Well 2 days later I drive it down the road, hit the gas to pass someone and my boost goes straight up around 25psi, and would have kept rising if I didn't let off. When I inspected the stock controller wires, they tapped the top hose into my intake right behind the MAF. Seemed kind've wierd to me, but I'm no expert. Does anybody know what's going on??

Thanks

 

[VelocitàPaola]

I just upgraded to an EvoIII16G and got the mitsubishi dealer to install it along with some other things. I included a MBC but they didn't put it on because they said the stock controller held it at 10psi, which was fine untill I do some other mods. Well 2 days later I drive it down the road, hit the gas to pass someone and my boost goes straight up around 25psi, and would have kept rising if I didn't let off. When I inspected the stock controller wires, they tapped the top hose into my intake right behind the MAF. Seemed kind've wierd to me, but I'm no expert. Does anybody know what's going on??

Thanks

It sounds like your BCS isn't working at all - as if it got stuck closed or something. I wouldn't mess with the BCS at all; just run a vacuum line from the wastegate actuator on the turbo to any vacuum port along the intake tract (i.e. compressor housing, J-pipe, intake manifold, etc.). Doing that should keep you boosting at no more than 10 psi.

By the way, I'm surprised that you got the dealer to install the EvoIII. How'd you manage that?

 

[weaver]

My T-25 blew and they were gonna charge me 1800 just for the replacement part! So I asked if I could buy my own stuff and he said yeah. The manager is a young guy with a couple of 3000's that he's got some serious mods on, so I think he just likes doing stuff like this.

 

[weaver]

So I go from the wastegate to the intake nipple that was put in behind my MAF? Or should I go ahead and just install my MBC that I bought?

 

[VelocitàPaola]

So I go from the wastegate to the intake nipple that was put in behind my MAF? Or should I go ahead and just install my MBC that I bought?

The nipple behind the MAF... I'm not exactly sure what you're talking about, but it doesn't sound like it's past the turbo. You need a boost source for the wastegate to work properly. Any port past the compressor housing should suffice.

By the way, the MBC you bought can't lower boost past the wastegate setting. If you're trying to keep the boost down, just setup the wastegate like this. You can always install the MBC later when you want to start boosting more.

 

[weaver]

The nipple I'm talking about wasn't there when I took the car in. They tapped one into my intake, right between the MAFT and the turbo. And that hose is going to the BCS, then another hose goes from the BCS to the Wastegate. Does this sound wierd to you, because I've never seen it like that before.

 

[VelocitàPaola]

Yes, it does sound pretty weird. It also sounds like it won't work...

You need to tee a vac line post-turbo for the wastegate to function properly; it works in response to boost.

Anywhere between the filter element and the turbo compressor inlet does not experience boost.

 

[MrBoxx]

They tried to set it up like it was on the T25, only they're missing one key vacuum line: the one that supplies the actual BOOST signal. Normally, it would be taken from the T25 compressor housing nipple. There is no such nipple on 16g's. Most people buy J-pipes or L-pipes that have a nipple tapped into them for a pressure source. I think the vacuum line from the BCS to the intake pipe is just a recirculation from the BCS's pressure signal from the turbo.

You keep mentioning you have a MAF and a MAFT; is this a GM MAF and translator, or do you mean the stock Mass Air Sensor?

What are you using for a J-pipe/lower intercooler pipe to the stock sidemount? To run an aftermarket MBC, drill a hold in the lower intercooler pipe, tap it, thread in an NPT nipple fitting, and use that for a pressure source.