Installed MBC - Turbo is out! But gauge still registers pressure! PICS

[ivj]

Ok here's the story. I got bought the following items from my friend for $20 - Turbo Gauge (with kPAx100 readings) and HBC (hallman) manual boost controller.

So first thing I do is hook up the turbo gauge. I tee it off the manifold-fuel solenoid line:

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I take the car out for a test drive. Seems to work fine. When idling, I'm a little over -500 kPa, when boosting full, I'm a little below 1,000 kPA (which's about 12 PSI, which's the factory boost). Sounds good.

Now I get ready to hook up the MBC. Now I notice that the relief hose coming off the boost solenoid is plugged with a screw. Shouldn't this give me 100% full boost? hmm. I'm ignoring this and proceeding with 1) homework 2) installation.

Now my understanding is the way that boost controll works is like this (factory):

We have a pressure line running off the turbo. The line splits into 2 lines - one to the wastegate actuator, and one to the boost control solenoid. The solenoid has another line coming out of it, which I understand is a relief line. When you're boosting, the wastegate opens up (which stops the boost), when those lines reach a certain pressure. The solenoid "relieves" that pressure, therefore delaying the wastegate opening, therefore controlling the boost. Am I on the right track here?

So, what I gotta do, is lose the solenoid altogether, and simply run turbo pressure to MBC to the wastegate actuator. MBC will act just like the solenoid did and would produce this kind of effect:

1) When open on full (aka no boost), turbo pressure will open the wastegate very quickly, and therefore you won't have any boost.

2) When closed (aka full boost), the pressure from the turbo will never reach the wastegate, and the wastegate will never open, giving me insane boost.

Am I on the right track here?

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So I hook up the MBC like so:

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Line marked #1 goes to the turbo.

Line marked #2 goes to the wastegate actuator.

I took off all the hoses from the solenoid, and left it sitting there, still connected to the wires (I have no idea what those do).

*** At this point I should note that I wasn't sure if this was the right way to connect those hoses. There were no instructions or anything for where the pressure comes in or where it goes out. What I did was I tried blowing into hose #2, and the air wouldn't come out of hose #1. But when I tried blowing into #1, the air came out of #2 (that was on no boost). So I hooked up #1 as the IN line, and #2 as the out line.

I re-connect my intake, BOV line, MAS, and the 2 other lines going to the intake (one ending in the intake manif, the other in on the valve cover). I set it to minimum boost, and take it out for a drive.

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As I'm driving, I give it full gas in 3rd going about 30 mph. WTF. My boost gauge reads just as much as it did before - about 12 psi. BUT! I feel no boost! AND, when I shift, my BOV makes a quiet "PFFFF", whereas in the past it did a very loud "PSSST" whistle.

I make a few stops and adjust the MBC, eventually turning it up to full boost. WTF! The gauge STILL reads 12 psi, and I still don't get no boost! Car accelerates noticably slower, and the BOV still makes a quiet PFFFF.

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What puzzles me, is why does my boost gauge still register 12 psi even if there's obviously no boost?

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OR is it possible that I actually still have full boost, but because I disconnected the solenoid, the engine doesn't give enough fuel and so I'm riding slower? But that wouldn't explain why the BOV doesn't make any sound.


This is really puzzling me, and I'd really like to get my turbo working again because now I'd probably get beat by civics. Any ideas or suggestions are most welcome! THANKS!

 

[turbo2g111]

Check for a boost leak. Try and reconnect your stock BCS and see if that cures the problem. If so, you've isolated your leak, and if not, then you have eliminated one possibility. If your boost gauge was reading correct before, and now at "full boost" you don't feel any, it is likely there is a leak somewhere.

 

[No_Skillz]

Plug your unused solenoid back in.

1) When open on full (aka no boost), turbo pressure will open the wastegate very quickly, and therefore you won't have any boost.

This assumption is false. You will run stock boost with MBC on lowest boost setting.

You also won't run any higher than 12psi no matter what you put your MBC on because you are still running the stock BOV. The 2g stock BOV is a plastice piece of junk that won't hold anything higher than ~12 psi, basically a massive boost leak. At the same time, you are overspinning your turbo. Get a new BOV before you turn up the boost.

And don't ever test a new part by turning the boost up all the way. Chances are you will hit fuel cut since the stock ECU doesn't like anything more than 25psi (assuming no boost leaks, less if there are), but at the same time you are toasting your engine by running too lean.

 

[ivj]

Well if you're thinking there's a boost leak - ut could only be in those 2 Hallman wires (they fit snugly on the hallman unit, but are fairly loose (easy to pull off) on the turbo and wastegate nipples). Guess I'll check that out and see what I can come up with.

As for BOV - should I look for one that blows off back into the intake? Any suggestions?

 

[turbo2g111]

1g BOV is the best for the price. Greddy Type S also works well. You should have one that re-circulates back into the intake because venting the BOV will cause many problems due to the difference between measured and actual air in the intake system. No_Skillz is right, I definately forgot, that piece of crap plastic 2g BOV will start giving you problemsat anything past stock boost. Is your MBC working? With it turned up to full boost, can you still blow through it? It could also be a problem with the MBC.

 

[No_Skillz]

Well if you're thinking there's a boost leak - ut could only be in those 2 Hallman wires (they fit snugly on the hallman unit, but are fairly loose (easy to pull off) on the turbo and wastegate nipples). Guess I'll check that out and see what I can come up with.

As for BOV - should I look for one that blows off back into the intake? Any suggestions?

Do a proper boost leak test. I'm sure you'll be astonished at the results.

As for BOV, I run a Greddy RS, since the type S is discontinued. A fitting is sold for it to reroute back into the intake.

 

[ivj]

How do you do a proper boost leak test?

PROBLEM SOLVED!

I guess I did have a boost leak after all. The hoses that come with Hallman MBC were a bit too big for the turbo and wastegate nipples. I kind of realized that from the beginning, but I thought it'd be fine if I just clamped it with a zip-tie. I guess I was wrong.

I got some smaller hoses from auto-zone, but I spent like 3 hours looking for a 1/8 to 3/16 hose adapter, which NOBODY had (autozone, shcuks, K&B, Lowes, Home Depot), I ended up buying 3/16 to 3/16 and forcing the 1/8 hose onto it. Worked pretty well, after heating up the 1/8 hose with a lighter and putting some motor oil into it

After hooking those up, my car drives like it did before (but for some reason I feel like the BOV doesn't sound as loud as it used to, but I think it's all in my head), so I guess problem solved.

Or IS IT? When turning the boost completely off, I'm still boosting to 12 psi. When turning it 100% on, I'm still boosting the same 12 psi. But that's for another thread.

 

[No_Skillz]

Or IS IT? When turning the boost completely off, I'm still boosting to 12 psi. When turning it 100% on, I'm still boosting the same 12 psi. But that's for another thread.

Did you even bother to read the posts left for you?

How do you do a proper boost leak test?

http://www.vfaq.com/mods/ICtester.html

 

[ivj]

Thanks for the link.

I did read what you said about not going below the stock boost with MBC, and it just sounds like a load of crap to me (no offense intended). I see people talking about turning boost down to 5 psi when breaking in the engine, etc, and just from what I know about how the wastegate works - the stock wastegate opens with about 7 psi, and when MBC is fully open, it allows 100% of the air through (hell I can blow through it), so it would keep the turbo at about 7 psi, not full 12-13 like I have now.

 

[No_Skillz]

Thanks for the link.

I did read what you said about not going below the stock boost with MBC, and it just sounds like a load of crap to me (no offense intended). I see people talking about turning boost down to 5 psi when breaking in the engine, etc, and just from what I know about how the wastegate works - the stock wastegate opens with about 7 psi, and when MBC is fully open, it allows 100% of the air through (hell I can blow through it), so it would keep the turbo at about 7 psi, not full 12-13 like I have now.

The stock wastegate on a 2g car for a t-25 keeps boost around 10-11 psi. Since all cars are different, 12-13 psi is in my mind an acceptable deviance.