no boost

[slow92lsr]

I recently installed my new punishment FMIC, during the process I also removed my exhaust manifold, turbo(14b), and my exhaust system. I put everything back on and I am almost sure that everything is hooked up right but when I drive it I can not build any boost. The guage goes from like 20lbs of vacuum up to 0lbs and will not build anymore. The only difference in the car is the new front mount and the only exhaust I have on is a 2.5" downpipe. I have tested the wastegate by applying air from a compressor and it opens and closes fine. Any ideas on what could be wrong?

 

[1992awdlaser]

Did you do a boost leak test?

 

[joyfil2001]

you have a boost leak. do a boost leak test.

 

[slow92lsr]

Thanks guys I know I should have checked but I tested it earlier so I ruled that out. It turns out I have a leak where the j pipe meets the compressor. Can I use rtv sealant to stop the leak?

 

[1992awdlaser]

Thanks guys I know I should have checked but I tested it earlier so I ruled that out. It turns out I have a leak where the j pipe meets the compressor. Can I use rtv sealant to stop the leak?

Use high temp copper rtv. Just put it on the outer part of the flange. You don't want any getting in the path of the air when you tighten it down.

 

[slow92lsr]

Ok so I fixed the leak at the compressor. I still can not build any boost! Any other reasons?

 

[silver bullit]

Did you check the wastegate and lines going to and from this to the bcs?

 

[slow92lsr]

Yes I tested the wastegate and I have a MBC.

 

[silver bullit]

How is the mbc hooked up and where is it tapped into?

Also what kind is it?

 

[MrBoxx]

Put the wastegate actuator arm back on the wastegate flapper arm? That usually results in a 0 boost condition.

 

[slow92lsr]

Right now the boost controller is tapped into the line coming off the blow off valve because I haven't put a hose barb on the j-pipe yet. It is a ball and spring MBC.

 

[GofaST4life]

Right now the boost controller is tapped into the line coming off the blow off valve because I haven't put a hose barb on the j-pipe yet. It is a ball and spring MBC.

you dont want to tap into the BOV line, thats a no no, so change that ASAP.

i have a ball and spring and it works fine, once you un-tap the BOV line post a pic so we can see if you have it hooked up correctly...

 

[slow92lsr]

I know its bad to run off the BOV line but I should still build some boost.

You must be logged in to view this image or video.

This is how the MBC is hooked up but my pressure source is from the BOV.

 

[rarson]

There's nothing wrong tapping off the BOV line. I've got multiple things tapped off my line.

What kind of BOV setup do you have? I've had leaks from there before. You sure you got the rest of the boost leaks?

 

[joyfil2001]

tapping the bov line is hit or miss. ive seen mbc's work fine hooked up to the bov. and ive seen others not build any boost. and then just recently i have seen it build to much boost regardless of where you set the mbc. Point - BOV not a good pressure source. did you do another boost leak test after fixing the j pipe? what is your boost gauge getting up to? is it dropping off slowly?

 

[slow92lsr]

I have the stock BOV. I did another boost leak test. I can not see my boost gauge because I am doing the test by myself but it holds pressure until I take the tester off of the turbo inlet because it releases pressure when I take it off.

 

[joyfil2001]

you need a helper. trust me, i did several boost leak checks by myself and i thought i had none. but i could see my boost gauge. i had a buddy help me out and he was able to look at the gauge and tell me what was going on.

 

[slow92lsr]

Ok I will have someone come over later today and look inside the car at the gauge and post back afterwards. Thanks guys for all the help.

 

[Boost92awd]

Make sure to use soapy water during your boost leak tests.

 

[slow92lsr]

Ok so I did another test with someone watching the gauges. I found several small leaks using soapy water. After I fixed the leaks the gauge would go to 20lbs and then leak down slowly. But I still can't build any boost.

 

[silver bullit]

The bov taped line needs to be fixed.

The reason you dont tap it is cause the air get diverted to the mbc bleeder hole, it bleeds of some of the pressure only allowing the bov to blow off slightly.

Just know its a no-no. They dont do this on stock cars for the same reason.


What kind of mbc is it?

 

[slow92lsr]

It is a homeade ball and spring type MBC that was on the car when I got it. The BOV line was tapped when I first got the car and I fixed it because I know it's not the best thing to do. I still should build a little boost, it feels like the turbo isn't working at all.

 

[silver bullit]

You checked the wastegate and did you install the mbc on another car to see if it works?

 

[slow92lsr]

I did check the wastegate, I put a hose from a compressor to it and watched it open and close. I do not have another car to put the MBC on but it worked fine before. I am going to try to find a hose barb for my j pipe tommorow or some day this week and run the MBC the right way and hopefully that will help.

 

[slow92lsr]

My car also has white smoke coming from the exhaust now. I don't know if the problem is related or not.