Need boost controller help

[delta448]

I bought a Turbo XS MBC off of someone on ebay a while back and have been using it for about a month or so. Today I tried to adjust the controller down from the roughly 15psi I had been running it at to 13-14psi in order to eliminate the possibility of over running the stock fuel system if I hit a boost spike. I had never had to adjust it before because it held at just under 15psi when I first put it on.

While I was adjusting it, I ran some brand new vacuum line from the pre-intercooler compressor piping to the MBC and then to the WG actuator. So after turning the boost controller down a couple of turns (each turn is supposed to equal 1 psi) I took the car out for a few runs.

There is absolutely no control over the boost now. I saw my boost gauge hit 28psi and flipped out, pulled over and adjusted the controller down a bunch more. No change. Adjusted back up past original setting. Still no change. WTF I cannot figure this out, unless the boost controller just died? There are no kinks in the vacuum lines.

Any help is greatly appreciated. Thanks.

-Zack

 

[95blackGsTurbo]

Try tightening it all the way down then see what happens. I would also make sure you didn't get it hooked up backwards or maybe even take it apart and see if you kinked the spring or something like that.

 

[delta448]

I have tried tightening it down all the way, it didn't help. It is not backwards, the brass nipple on the side is connected to the compressor to intercooler tubing and the blue bottom nipple is connected to the WG actuator. The Standard Turbo XS MBC does not have a spring, if I understand correctly, instead it uses a bleeder to let out some of the pressurized signal to the WG. The adjustment is supposed to control how much pressure is bled off and thus control the boost pressure reached before enough pressure signal hits the WG actuator and opens the WG.

Update: Well, I thought I had fixed the problem, by zip tying the slightly-oversize vacuum lines down really snug to the nipples but I guess that was short lived. I went up the interstate on-ramp a little while ago to go across town and was accelerating fairly moderately in 3rd gear and as soon as I hit 4th, boom the boost spiked to 20+ and I almost pegged the tach because it came on so hard. From then on I had little or no control above 3k rpms. WTF

 

[alex99gst]

I have tried tightening it down all the way, it didn't help. It is not backwards, the brass on the side is connected to the compressor to intercooler tubing and the blue bottom is connected to the WG actuator. The Standard Turbo XS MBC does not have a spring, if I understand correctly, instead it uses a bleeder to let out some of the pressurized signal to the WG. The adjustment is supposed to control how much pressure is bled off and thus control the boost pressure reached before enough pressure signal hits the WG actuator and opens the WG.

Update: Well, I thought I had fixed the problem, by zip tying the slightly-oversize vacuum lines down really snug to the s but I guess that was short lived. I went up the interstate on-ramp a little while ago to go across town and was accelerating fairly moderately in 3rd gear and as soon as I hit 4th, boom the boost spiked to 20+ and I almost pegged the tach because it came on so hard. From then on I had little or no control above 3k rpms. WTF

The fitting on the side needs to go to the wastegate and the fitting on the bottom needs to be hooked up to a pressure source like the j-pipe, preferrably not T'ed off of the BOV line. Run the BOV line by itself to the intake manifold.

Try running the lines like that and be sure to back the screw out a lot if you had it all the way in like you said. Also for my MBC I use 3/16" hose. This is larger than the factory vacuum hose, but it was what came with my MBC.

 

[kottyking]

I second alex's motion. Just start over, take a breath, tighten the allen screw down aways, reconnect, then set to your desired boost.

 

[delta448]

The instructions on Turbo XS's website say that the side connects to pressure and the bottom connects to WG actuator.
http://www.turboxs.com/faq/eclipse2.htm

Also, since this is a bleeder style controller and not a ball and spring style, if the screw is all the way in there should be no increase in boost over the WGA spring rating since the bleeder hole is completely sealed. With the screw all the way backed out, the boost would be infinite. See above posts.

The setup on the car has the BOV line connected only to the intake mani and the WGA connected only to the Tube off the J-pipe. No BCS, or other controller except the WGA spring was used to control boost when I bought the car in December. It would run 10psi max in that configuration. After adding the MBC and not adjusting it at all, pressure would stay around 14psi sometimes, but rarely, spiking to 16psi.

Does anyone else use a Standard Turbo XS MBC or any other bleeder style MBC? Maybe I'm missing something obvious here.