Boost?????

[jhines]

I have recently began to fix some problems the previous owner of my car created. I put on a EVO 16G, O2 housing with full 3.5" exhaust and no cat. But he had removed the stock bost controller(hence the blown t-25), but I now have a manual turboX's boost controller. Yet I still cannot control boost pressures, at all!!! All turbo parts are brand new from SBR with a 14lb. wastegate spring. The spring will open the wastegate when you manually apply pressure, my vacuum is 17" at idle, and I have no known leaks on either side of the turbo. Does anyone have any idea why I may be having trouble and having absolutely NO boost control? This thing has me puzzled and many of my fellow turbo buddies wandering too.......any help or ideas would be appreciated greatly.....
thanx,
-Hines

 

[EclipseTrbo420A]

where are you getting the pressure sorce from for the boost controller?

 

[jhines]

I have the SBR 16G install kit which came with an access pipe on the compressor side of the turbo. So on that pipe, there is a nipple that you use to tap into the pressurized side of the turbo; that's where i have tapped into, an that is the recommended tap spot. People are telling me that it is the rings or the wastegate, but both are fine......just wondering if exhaust could be the problem b/c people say that i may have NO backpressure, but the system still has a muffler and resignator, just no cat......i dunno. It's got me.....but it is definitely annoying b/c it is literally 5 seconds between 10 psi and fuel cut.

 

[EclipseTrbo420A]

Ok first just run a line from the nipple on the j pipe to the wastegate actuator and if your cars build and holds boost at anywhere from 11-13 lbs your wastegate is fine and the mbc is the problem. Try that first.

If thats so, then make sure you using the MBC correctly like which way your adjusting the screw, and which direction you have the pressure traveling through the MBC.

 

[jhines]

I have already ran straight pressure to the wastegate like you are talking about, still nothing. I have also traded off wastegates with my buddy who has the almost identical setup, but working, and my car still boosts out the roof. I have checked basically every aspect of the pressure system, replaced all vacuum line and all pressure hoses with thicker-walled hose(in case they were collapsing) and checked the whole system for a leak....nothing!! I've done about everything that you would regularly expect, but I am farely new to the DSM world, so I dunno all the little back doors and tricks to the diagnosis yet.
-Hines

 

[Mr4G]

dont use the nipple on the turbo. use vacum line to run from the wastegate actuater and the nipple on the j pipe to a tee to the boost controller to the niplle on the aircan.

 

[oldman]

dont use the nipple on the turbo. use vacum line to run from the wastegate actuater and the nipple on the j pipe to a tee to the boost controller to the niplle on the aircan.

That is not right, that is how a stock bcs is setup, not how a mbc is setup. Your setup will result in stock actuator boost without control.

jhines, does boost pause a bit at 10-12psi then creeps up as rpm increases?

 

[jhines]

Oldman,
It is not really a creep, in 2nd gear....i can go from like 2lbs to 24lbs in under 45 sec. So i know that it is not creep, it is like absolutely no pause in the climb. It did this before i got my new(EVO 16G) turbo setup. I don't think the guy I bought the car from new exactly what he was doing, so i dunno 100% what he did. I tried to fix as much as I could, but I may have missed something. Any other ideas?.....thanx
-Hines

 

[oldman]

It is not really a creep, in 2nd gear....i can go from like 2lbs to 24lbs in under 45 sec.

That's pretty slow.

So i know that it is not creep, it is like absolutely no pause in the climb. It did this before i got my new(EVO 16G) turbo setup. I don't think the guy I bought the car from new exactly what he was doing, so i dunno 100% what he did. I tried to fix as much as I could, but I may have missed something. Any other ideas?.....thanx

What about 3rd? Sometimes it's hard to detect creep in 2nd because eveything is so fast. I still think it's creep because,

1. 3.5" exhaust , why?

2. You have test run with just a hose between j-pipe and actuator.

3. You have applied pressure to the actuator directly to verify its integrity.

Unless the hose between the j-pipe and the actuator is all chewed up, everything points to boost creep. BTW you don't need to boost to 25psi to know you still have no control.

 

[Mike Marnik]

Ya it definatly sounds like boost creep just really really bad boost creep. You say the actuator work properly, but did you test that when you had the arm off of the wastegate or on. The wastegate itself might be stuck shut or not opening fully.

 

[jhines]

I did try the whole full-motion movement of the actuator arm and also apply pressure to see if it opens and holds, which it passed all tests i did, both on and off the car. But to answer your question oldman, it does the climb in every gear.....3rd gear pull is not as bad as 2nd, but it is still very noticablya FAST and steady climb. And just so that you will not think I am stupid oldman, I don't bounce the car off of the fuel-cut, but once it hits about 18-20lbs......I know that it would go all the way, but I'm not gonna let it rise and chance pulling my stock 2G head off the block. I have been in several turbo cars that have the whole boost crep idea that will slowly climb like 4-5lbs., but nothing like this thing......it's crazy how fast it builds boost up!!! But let's say for example it is boost creep, what do you recommend? I've been told to port wastegate, turbine housing, O2....different things. But I don't think it is anything with that new system i have put on the car because it did it with the stock t-25, stock O2, stock everything. Anything else you could think of?
-Hines
And the exhaust is Espelir 85mm from RRE that replaced the straight mandrel-bent piping the guy had ran from the turbo all the way back before. What real "bad" effect could the 85mm exhaust have on the system as long as i still have at least a little bit of backpressure?

 

[oldman]

At what rpm are you hitting 25psi?

There are only 2 possibilities here, infinite boost or boost creep. If it's infinite boost, it can only be either a defective wastegate actuator, stuck closed flapper or lack of intake pressure to the actuator in which have all been eliminated according to your posts. My old small 16g with 2.5" exhaust with cat, with mbc bypassed, used to hit 12psi for a second then creeps to 24psi at about 5.5k-6k when I hit fuel cut so don't underestimate boost creep.

If you're hitting 25psi before 4k, you probably have infinite boost. If you don't hit 25psi until 5k+, you most likely have boost creep. Anything in between would be inconclusive.

 

[jhines]

Thanx oldman, I not exactly remember when it hits cut, and the car is back home.....so i'll have my dad go beat on the car a little bit and see where abouts it hits the fuel-cut, or at least close to it. If you would, keep this post in mind and I will get back to you with my results hopefully in a day or two at the most.
Thanks again, you've been a great help
-Hines

 

[oldman]

You're welcome and good luck, just post back what you find.

 

[fsu99gsx]

Im not saying this is your problem, but this is what happened to me. I installed a new turbo and had uncontrollable boost exactly like your saying. I couldn't figure it out for anything. I tried an electronic and a manual boost controller and still no control. Then at last I took the wasteate actuator arm off to check if the wastegate would open at all and realized that when you opened it there was a little spot where it would kinda catch. It should be very easy to open with no resistance at all without the arm attached. Just an idea since it seems that you've tried everything else like I did. I just swapped the turbo's exhaust housing and the problem was solved. good luck I know it's fustrating

 

[jhines]

Yea, I had thought about that too fsu99gsx, but my buddy(Skywalker18 on this site) has the exact same setup as me and we did the swaps like 2 weeks apart......yet he has absolutely NO problems at all. But yea, I had thought about a tubular exhaust housing with a dumped O2 anyway, so I may go ahead and make that piece up and try it out. But thanx for the input man.
-Hines

 

[Mr4G]

look, oldman, why would it be different routing from the bcs. if mitsubishi wanted it that way it s for a reason. i have done that on all my turbo cars and never had an uncontrollable boost problem. Besides, have you ever tried it this way. it works the way i stated from 12 psi up to 38 psi.

 

[oldman]

look, oldman, why would it be different routing from the bcs. if mitsubishi wanted it that way it s for a reason. i have done that on all my turbo cars and never had an uncontrollable boost problem. Besides, have you ever tried it this way. it works the way i stated from 12 psi up to 38 psi.

By your logic, every dsm should be stock since Mitsubishi probably wanted it that way for a reason. What reason do you think Mitsu have for using a cheap 1g cast manifold that cracks? That's right, cost.

The factory bcs is a bleeder type valve, it works by bleeding pressure off the actuator line therefore reducing the pressure signal sent to the actuator. Why is this a problem you ask, because it's essentially a huge boost leak as well as inconsistent boost control. An aftermarket mbc, except bleeder type valves like the standard version of the TurboXS mbc, controls boost by blocking pressure signal to the wastegate actuator using ball and spring, it then releases the signal to the actuator when the spring tension is overcome by the intake pressure.

The reason it worked for you is because you're using the mbc to create a boost leak, just like the factory bcs, making your turbo working much harder than it needs to as well as losing performance. You might as well just sell the mbc and either hook back up your bcs or just punch a hole in the vacuum line to the wastegate actuator. I hope I made it clear.

 

[jhines]

oldman, your comment on the TurboX's mbc, so if when using that valve, you read say 15psi, you are not actually getting that 15psi to the engine. I am just wondering because I just bought a TurboX's because it is what people had told me to run on my setup until I could get a electronic or a better one. I have not used the controller because I cannot even controll boost straight wastegated. Just wondering. And my dad ran my car, but did not catch the RPM. He is going to do it again for me, but he did say that the boost spikes at 24 and then drops back and picks up around 15 or so. But I will get you that RPM reading ASAP. Thanx.......
-Hines

If this turns out to be a severe boost creap, what would you recommend. I have ben told to try porting my wastegate and the turbo outlet and try another O2 housing. I was going to either make a dump-style O2 or buy a cheap one and stick it on there and drop my exhaust off and try that setup with an open downpipe to make sure the stuff isn't causing the problems. Just wondering what you would suggest because I am sure you have been dealing with the many DSM issues for much longer than me.

 

[oldman]

Let's wait for your dad's test results before we go further on both the TurboXS mbc and solutions for boost creep. Ask him to be as detail as he can be on both rpm and psi, also to let off at about 20 psi, there is no need to push it to 24psi.

 

[Mr4G]

1st of all, hines do not go with an electronic boost controller. they become inaccurate a higher boost levels. a mechanical one is much better. and 2nd, oldman, you did not clear anything up because all you are telling me is i m wrong. if i m wrong then tell me the correct way to do it then i will be able to understand you.

 

[oldman]

and 2nd, oldman, you did not clear anything up because all you are telling me is i m wrong.

I don't know how much more clear I can be, just because you didn't understand it doesn't mean it wasn't clear.

if i m wrong then tell me the correct way to do it then i will be able to understand you.

First tell me which type/brand/model mbc you have, not all mbc's are hooked up the same way.

 

[Mr4G]

i make my own boost controllers. they include a spring and ball. also about not being clear, alls you have been doing is telling me that i m wrong and not telling me what the right way of doing something is. i can explain why people are wrong too but i dont, i tell them how to solve the problem of them being wrong. you should try that sometime instead of trying to act smart cause all i think of you is someone on this sight who likes criticizing people and trying to show off their knowleadge instead of helping them.

 

[oldman]

If you want to have an adult technical discussion about which way is the correct way to hook up a mbc, present it as such and I'm all ears. If you're sincerely about learning how to hook up your ball and spring type mbc properly, ask repectfully and I'll be happy to help. If you're just butthurt about being corrected because you posted mis-information, please stop wasting our time and space by hijacking this thread. One thing we don't do on tuners is flaming and personal attacks, since you're new to the site we will let this one slide but consider yourself warned.

 

[jhines]

oldman, take a look at these pix.......

http://m04.webmail.aol.com/15106/ai...d=2&saveAs=boost_controller_hookup%20copy.jpg

My buddy sent me this and read the article on it, it makes a lot of sense and all......just wonderting what you think about it.