Boost issue

[1996dsm]

Im having an issue with my boost, when i go full throttle the boost ranges from14 and goes down to 10 and so on. It never overboosts, but boost drops as im WOT. i have not done a boost leak test(havent made one yet). but im wondering if that may be the issue, i dont hear a leak though.

 

[Cassera]

Im having an issue with my boost, when i go full throttle the boost ranges from14 and goes down to 10 and so on. It never overboosts, but boost drops as im WOT. i have not done a boost leak test(havent made one yet). but im wondering if that may be the issue, i dont hear a leak though.

You should just wait until after you do the boost leak test, THAN post and tell us whats up......Look at it from our perspective. (I'd bet it's a boost leak though)

 

[kottyking]

In your profile, it doesn't say what bov you have. Is it stock? I'm assuming its not stock since you have a FMIC kit...

 

[1996dsm]

I have not made and have no extra cash at the moment, for a boost leak tester.

And i have a knock off greddy BOV(got it free).

Just wanted to know if it sounded like a boost leak problem, so i know what to look for.

 

[kottyking]

Make sure the bov is set correctly as well, if you have to properly "tune" the soft hard setting on the top of the bov. But as far as a boost leak tester make on cheap! IC Pipe Tester

 

[1996dsm]

Forgot to mention it does all this without the boost controller, the boost goes from 14 to 10 very slowy through the rpm's.

 

[kottyking]

So the boost control solenoid is still activating it?

 

[1996dsm]

So the boost control solenoid is still activating it?

No its running from turbo nipple straight to wastegate.

I hooked up MBC just now and it does the same thing, The boost is still fluctuating.

 

[kottyking]

So there is nothing controlling it so to speak. It's gonna open and close when it wants. You installed the MBC correct right? http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/237982-best-way-install-mbc.html

I think with the way you have it, there's not gonna be anything controlling it if I'm picturing what your talking about correctly. If thats the case, the only thing controlling boost is the wastegate spring pressure which is around 12 I believe.

 

[1996dsm]

Turbo XS - WRX, STi, EVO SRT4, Subaru, Mitsubishi, Turbo, Turbocharged

i have the high performance boost controller, i hooked the turbo nipple to the bronze side, and wastegate to the other. Is this correct?

 

[kottyking]

Did you READ THE LINK I posted for you in my last post? It tells you how to properly install it...

 

[1996dsm]

I did look at post, nipples are diff from the mbc i have so i was mixed up. I hooked it up right, must be a boost leak. I had a boost leak before, so you usually hear it. I hear no whistle or anything.

 

[BoostFrenzy]

It looks like you are running a stock T25 no?

There's your answer. Do a BLT anyway when you get the cash to make one.

 

[1996dsm]

i will try to do a BLT tommorow if i can. never done one before, seems simple enough....

 

[Cassera]

Nobody thinks it could possible also be a waste gate problem?

 

[BoostFrenzy]

Nobody thinks it could possible also be a waste gate problem?

If they are still on the T25 it is mainly the whole turbo that's causing the problem. The only solution that I have seen to it was the FP 17PSI Actuator.

 

[1996dsm]

If they are still on the T25 it is mainly the whole turbo that's causing the problem. The only solution that I have seen to it was the FP 17PSI Actuator.

I read the description in the link, Sound kinda like my issue the higher the rpm the lower the boost. But i have another wastegate from another t-25, i haven't made a blt. I might try switching wastegates here in the next few hours.

 

[Cassera]

I read the description in the link, Sound kinda like my issue the higher the rpm the lower the boost. But i have another wastegate from another t-25, i haven't made a blt. I might try switching wastegates here in the next few hours.

Let us know how it works

I figured since you were going back and forth between 10 and 14psi (instead of other people describing a change between 6-7 psi) it would be a waste gate problem instead of a leak somewhere else or any other thing.

 

[1996dsm]

Did a boost leak test, and its leaking very bad at the gasket for the BOV, and biss, and throttle body gasket. I will fix all leaks asap and perform another BLT.

By the way the boost leak tester shot the end cap off at 17 psi, haha scared the shit out of me...

 

[MJBean420]

I bet you the leak is on the exhaust side. check the connections on the exhaust manifold.

 

[1996dsm]

actually my tubulars were cracked, so im now running the stock mani. but it did not help with the issue.

Fixed all the boost leaks, pulled a LOT harder. BUT my boost is still fluctuating, so im gonna let it cool down and im going to try putting my other wastegate on. and my damn o2 dump is blowing right on my lower intercooler pipe, i need to add an extension to it and dump farther down. Any suggestions to all this?

I fixed all the boost leaks, car pulled much harder. BUT my boost is still dropping. I am going to let the car cool down and then try my other wastegate. After a 2-3 pulls the car is much slower. I think it is because i have a o2 dump and it is about 5-7in above my lower intercooler pipe. any suggestions?

 

[1996dsm]

????

I dont know what the problem is im clueless. I fell like selling the damn car, over something so small. i re did all my couplers, took off tubo to take off o2 dump. one of the bolts is stuck on the o2 dump, so i could not get it all the way off(wastegate flapper was sticking so i cleaned it up). Ive been working on it for the last 7hrs. im to the point where i dont wanna see the car. no boost leaks, good wastegate, no shaft play in turbo, BOV adjusted properly, MBC is on correct....

 

[RavenX]

If you are on the stock T25 boost will go down as RPM's go up. Nothing you can do about it unless you get the stronger wastegate arm or get another turbo.

 

[BoostFrenzy]

If they are still on the T25 it is mainly the whole turbo that's causing the problem. The only solution that I have seen to it was the FP 17PSI Actuator.

I am going to restate this and hope it sinks in.

You have to think of your motor as an air pump. The higher the RPMS go, the more air that is required to fill the chamber. If you are running a smaller frame turbo, then the manifold pressure will start to die off as the RPMS rise because it can't keep up with the flow required to fill the 1997CCs of volume that it is breathig in and out at an accelerating rate.

But also the more air you push into the engine, the more air that gets pushed out. In doing so you can blow open a wastegate with not enough seat pressure to withstand the force.

You have a combination of both.

 

[1996dsm]

I am going to restate this and hope it sinks in.

You have to think of your motor as an air pump. The higher the RPMS go, the more air that is required to fill the chamber. If you are running a smaller frame turbo, then the manifold pressure will start to die off as the RPMS rise because it can't keep up with the flow required to fill the 1997CCs of volume that it is breathig in and out at an accelerating rate.

But also the more air you push into the engine, the more air that gets pushed out. In doing so you can blow open a wastegate with not enough seat pressure to withstand the force.

You have a combination of both.

Thanks for the info, I guess when i get around to it i'll just replace the turbo with another(not t-25). But even with your theory, it never done this till a few months ago. I guess the miles are catching up with the turbo...