MBC and Late spool

[walkman19]

Hey guys whats up?

Well I have two questions.

First is I Bought this car with a MBC that was T'd into the BOV line. Now that I decided to increase the psi since I installed the turbo I went to do that only to find out that turning it either way all the way doesnt change my boost on my aftermarket gauge it only boosts until 8psi then stays steady until I shift then reboosts back to 8 psi (if i choose to). Im assuming that the MBC is broke and ill need a new one? Also I plan to reroute it off the j-pipe

Second is I'm glad I finally installed the turbo that I got rebuilt from JUSMX141. But I't didnt really hit me until today. I tried it out against 2 other cars off the line. I first thought that the actual boost/pull was supposed to happen around 6-6.2k rpms like it has since I installed the new rebuilt turbo. Then I did some search considering I was losing to a scion and a galant WTF and realized most people were hitting FULL BOOST i.e 20 psi @3.2-4k rpm if not sooner if that, while I could only hit 8psi @ 6k rpm. I do hear the turbo spooling from outside the car usually between 2.8-3k rpms but when I go from stop and into first I dont feel any boost/pull until around 6k.


Now im wondering is there any way that the MBC could relate to the very late spool?? And if not possibly why is my spool so late ..

I appreciate everyones help in the past and the future help..

Thanks in advance!

 

[MJBean420]

Try searching to find the thread that connects the MBC directly from the wastegate to a nipple on the intake side of the turbo. I had a similar issue with my MBC initially, then hooked it up the "correct" way and it made a huge difference.

Basically the MBC is inline from the wastegate to a direct vacuum line off the turbo. The MBC retards the wastegate from being activated until the desired psi level.

 

[my dreamt dsm]

I didn't T mines to the bov and it worked just great. I just have mines to the wastegate and compressor housing!

Dsm best way for boost controller image by francoswc on Photobucket
Turbo Modifications To My 1997 Eagle Talon TSi AWD

Hope that helps! *winks* no one gives rep points no more. ha!

 

[synthetek]

Did you do a boost leak test after installing the rebuilt turbo?

 

[gst fat]

The mbc is not suppose to run to bov, it's suppose to run from the wastegate actuator to the intake side nipple of the turbo! That's I run mines it's the basic turboxs one and I'm boosting 22lbs. On a 57 trim

 

[standard235]

If you mean the compressor outlet, that isn't the intake pipe side. That would be the J-Pipe or compressor cover...

 

[walkman19]

Did you do a boost leak test after installing the rebuilt turbo?

Nope I'll probably do that today

If you mean the compressor outlet, that isn't the intake pipe side. That would be the J-Pipe or compressor cover...

My bad actually the next part of my intercooler piping right after the j pipe has a covered up nipple that I would be using then run it to the MBC then from there to the nipple on the wastegate

 

[KKneipper]

If you T your MBC on the BOV line, you're letting a tiny amount of pressure out of that line, and your BOV isn't being fully pressurized. Run it from the nipple on your compressor housing to your wastegate, and plug off your wastegate solenoid line that was running to those 2 ports. That's how I have mine and am running 17 psi all day long with no issues.

 

[walkman19]

Found the problem.. for those of you experiencing the same problem what I did was removed the MBC and the lines with it and sealed up the nipple that was coming off the vacuum line to the BOV.. I then took it out and boosted it slowly it DID go above 8 psi this time. So I need a new MBC and also to reroute the line onto the compressor housing (well im going to use the IC piping).

Only thing that sucked was when I boosted it the second time my IC piping shot off only under 12 psi >:0 So i pulled over at my friends jacked it up.. tested it out and same thing happened in the same place. (it happened twice prior to this.)... sigghhhh yay another problem.. So now im going to run up and try to buy some bigger silicone couplers because I believe that the one on there is not long enough and also some stronger T clamps..

 

[KKneipper]

I have the same problem with my IC piping. It blows apart when I hit full 17 psi. I need to get a 2 1/4-2 1/2 inch coupler, but cannot find one anywhere near me. So I just turned my boost down to stock 12 psi for the moment. Good luck with it.

 

[walkman19]

I have the same problem with my IC piping. It blows apart when I hit full 17 psi. I need to get a 2 1/4-2 1/2 inch coupler, but cannot find one anywhere near me. So I just turned my boost down to stock 12 psi for the moment. Good luck with it.

I got mine yesterday at a local hydraulics place 2 feet for $30 now I just got to cut it and fix some pipes and replace the existing ones and HOPEFULLY it works, but then I'll just be ready for the next problem

 

[1SloEvo]

Found the problem.. for those of you experiencing the same problem what I did was removed the MBC and the lines with it and sealed up the nipple that was coming off the vacuum line to the BOV.. I then took it out and boosted it slowly it DID go above 8 psi this time. So I need a new MBC and also to reroute the line onto the compressor housing (well im going to use the IC piping).

So you're saying you have no vacuum line connected to your BOV right now? That would NOT be the thing to do. The pressure that goes through that line helps the BOV stay closed when under boost...which is now why you are probably only getting 12psi. The BOV is probably leaking at that point due to the spring seat pressure. You need the vacuum line going to the BOV from the manifold. And you should use the nipple coming off your intercooler piping! That would probably take care of your problems.

 

[Jiggalude]

Yea you need the line hooked up to the BOV, otherwise 1 psi of pressure and it will start leaking. It needs the pressure from the vacuum line to hold it closed. Also, your BC probably isn't bad, it was just hooked up wrong. You need to tap into the compressor housing or J pipe for a boost source, and the other side of the BC to your wastegate.

 

[1SloEvo]

The intercooler pipe will work fine for his boost source for the wastegate without causing him any trouble of pulling parts to have a nipple welded somewhere else. As for the BOV, it shouldn't crack at 1psi. There is a spring in there that works very similar to a wastegate. The spring has a preload that's rated at a certain amount of pressure (not sure what the stock bov is). It should hold until that amount of pressure without leaking. Beyond that, it should leak. The vacuum line provides the extra pressure needed (to an extent) to keep the BOV closed under higher boost pressures than the spring is able to.

 

[walkman19]

It was T'd off my bov line so the line is still there I just covered the extra part that came off the T and now goes nowhere

I also did use the nipple off the IC piping but once again no
matter what way I turned it it still only boosted to 7-8 psi