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Boost Controller Vac line ?s

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gats0101

20+ Year Contributor
68
1
Apr 3, 2005
overland park, Kansas
I recently installed a Slowboy Boost Controller and am having trouble setting a boost level. I have the controller set as low as possible with the spring still touching the ball bearing inside (which should be the wastegate setting 8psi), and it boosts indefinately, like its setup backwards. I took the screw out and blew it out, put it back together, and hooked an air pressure gauge to the wastegate side of it and blew air through it and it opened like it should(just over 8psi). Then during lunch I put it back on the car, and I'm still having the problem of no control over my boost. I hooked up the vac line from the compressor outlet (what I'm using as a pressure source) straight to the wastegate and it opens at 8psi like it should. So what I can gather from my tests, my source is alright, my wastegate is working, and my boost controller is working and hooked up correctly. So now what? My friend that is our mechanic at the body shop I work at suggested that I swap out the vac line I'm using from the source to the boost controller. His theory was that the line was expanding or ballooning and wasn't applying the air pressure to the ball bearing to open the controller. What do you guys think about this? I'm gonna try it tomorrow and see how it goes. Has anyone ran into any kinds of problems like this before? I've installed a couple manual boost controllers on some different cars before and never had a problem like this. Any input you guys could give me would be great. Thanks sam g
 
First of all, What happens when you run a straight vaccum line from a boost source to the WGA?

Also, what size exhaust do you have?

I would change out all of your vaccum line, try running a direct boost source line, and then go from there.

Chris
 
When I run a line straight from the source to the wastegate I run about 8psi. Thats how I'm currently driving my car. My 92 AWD is all stock except for a K&N filter and slightly cut air canister, so stock exhaust. Today after work I went and bought new vac lines and still no control over my boost.
 
If the vacuum lines are hooked properly, compressor fitting to the MBC fitting that is inline but opposite to the adjustment knob and the MBC perpendicular fitting to the wastegate, the issue here clearly is the MBC.
 
Thats how I had it hooked up. Its a wierd deal. I got the boost controller to open with an air line at work the other day but hooked up on my car it doesn't work. I'm trying to return it right now. Hopefully SB will take it back and send me a new one. I've been talking to them through email since I posted this but its kinda slow going since I don't have regular access to a computer since my laptop decided to jump off my bed and crack the LCD screen.
 
Thats how I had it hooked up. Its a wierd deal. I got the boost controller to open with an air line at work the other day but hooked up on my car it doesn't work. I'm trying to return it right now. Hopefully SB will take it back and send me a new one. I've been talking to them through email since I posted this but its kinda slow going since I don't have regular access to a computer since my laptop decided to jump off my bed and crack the LCD screen.
Sounds like the bleeder hole is too big OR the body/fitting of the MBC is leaking.
 
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