3 inch exhaust, 16g...20 psi.. what can i do to lower the boost for safe driving...

[XilArAtiNG]

I searched for this and didnt really get all the greatest answers but, how would i go about lowering the psi from about 20 to a relitavely safe 14-15 for a daily driver. Vehicle is a 1993 Tsi awd, dejon tool intake, 16g, full magnaflow 3 inch exhaust with no cat. My friend said you can get a smaller (2.5 inch) down pipe, port the turbo or get an external wastegate dump, do those sound legit? This is my friends car that im thinking of purchasing. So a little help would be nice, thank you in advance!

 

[dsmmike50t]

Boost controller

 

[pitbull419]

Does it jump to 20psi or slowly raise?

 

[XilArAtiNG]

it rises as it should, it doesnt spike.

It has a T type manual boost controller, dont help.

I read somewhere if you get a really weak wastegate spring it should work? but wouldnt that just spin the hell out of the turbo and work it hard for nothing.

 

[96gst_4life]

get a boot controler if you have one just turn it down? you can also just port out you o2 manifold or get a o2 mani that dumps.. the larger the exhaust the less backpresser wich will give you a boost creep thats if you are running a stock wastgate...

 

[gats0101]

Can you give us a little more information on the car? Does it have a boost controller? Does it still have the BCS on it? Porting the exhaust side of the turbo and O2 housing does help.

 

[gats0101]

I didnt see the posts before me, try turning the boost controller all the way down, as loose as possible, or completely take it off and see what boost you are running.

 

[gats0101]

also make sure you have the boost controller installed correctly.

 

[XilArAtiNG]

Ok thank you for the help, will def try to play with the manual boost controller tomrow.

Also, will an aftermarket wastegate help this? if so which ones should i go with.

Thank you for the help

 

[winterftbl]

Aftermarket wastegate will only help if it is an external gate, not internal.

 

[GUTSI]

Ha ha I felt your pain brother....had a very similar setup with the evo 16G, 3in exhaust..blah blah ya know, the works. Even had all the necessary requiremts to PREVENT boost creep (i.e ported O2, turbine, 34mm mod etc etc)...
...and guess what? It would creep to 25 psi...all the time..no problem ! Gotta admit, it was exhilarating to drive, but obviously dangerous and fuel cut was no fun.

We even took the turbo off and disconnected the actuator arm, expecting about no more than like 8 psi and the turbo should've fell flat on its face... Instead we got a solid 15 psi, with nothing holding the flapper back!! Couldnt figure it out!!

Apparently its common with free flowing 3inch exhausts and the evo turbo (also heard that it might be a design flaw with the actuator/flapper on mitsu's part...but i just heard...so.....)
Worse case scenario (and i use "worse case" very loosely):
38mm external gate and a manny to match. And a proper weld job on the flapper.

Have that same set-up, and to be honest, I'm glad i had the boost creep problem..otherwise i would've never appreciated the full function of a WG.
I dont use a boost controller (its there, its set, but the switch is off) and I get a solid 14 psi ALL the time...warm hot cold weather..doesnt matter. The WG strictly controls my base boost...If I need more boost, jus flip the cockpit switch up, and I get 17 psi on tap.

Once you go external...you'll never go back!! Not to mention the expressions on faces as you scare the sh!t out of every living thing in your vicinity!!
....but if your not into that, you can always plumb it back in...

 

[marq95gst]

Yeah, sounds like you're creeping there. Like others said, boost controller (double make sure its hooked up right), then port your turbo hotside and o2 housing. I did that with my FP28 and totally helped.

 

[DSM LoVeR 96]

boost countroller bud

 

[turbomoe]

boost contorler. or adj. waste gate rod

 

[underradar92]

Here is a great post on how to end boost creep. http://www.dsmtuners.com/forums/art...oler/186525-how-cure-boost-creep-porting.html

 

[TalonTSIawd1991]

You could adj the wastegate rod, but its easier to use a boost controller.

 

[KiNg MaRtY]

A better MBC should help out or a EBC with a safety.

 

[GUTSI]

To be honest boys, I dont think his issue can be remedied by a boost controller...
His issue is creep...its creeping because the excess boost is makin a mockery of the evo 16g's weak internal wg design. Basically, the turbo is running atmospheric pressure, which means its gonna continue spooling as much as its capable, and usually that'll end around the 20-25 psi range, only because of the inevitable fuel cut....
...fuel cut is what's saving his turbo and motor, otherwise the thing would just spool itself into oblivion!

Besides, he's got a mbc, AND, he mentioned he's got no cat!! I mean, aside from having the proper port work and such, and that bs waste of time flapper mod, I think you'd benefit from a WG either way...or even an O2 with a dump....it just gives you that extra needed precision and control of your boost, especially if you have future plans in terms of actually running the 16g in the 20 psi range

Again boys, just relaying my personal experience with the exact same situation here...

 

[kenamond]

I agree with GUTSI for the most part.

You can test for creep a couple of ways. Disconnect the WG arm from the lever and check that you can turn the lever by hand easily (on a cold motor!). If it turns freely, do a test run like this and see how high your boost goes. If it goes above ~5psi, it's probably a creep problem. If it doesn't go above that, it might still be creep.

The WG design on the evo3b16g isn't necessarily flawed. It wasn't designed for our car. It is true that it is not great when applied to our cars. The WGA has a very short throw, so the arm only causes the lever+WG flapper to open maybe 30°-45°. There's a fairly recent thread about modding the WGA by hacking two apart and putting them back together with a much longer throw, but that requires several hours of tinkering.

Most of the following cures have been listed already, but not all:
Port the WG entrance in the turbine housing (the link to the boost creep cure thread describes this)
Go to an external WG.
Mod the WGA to have a longer throw.
Get supporting mods to run 20+psi safely.

I wouldn't consider adding restrictions to the exhaust a solution to creep. But it might still be an attractive alternative to anything else in the list above.

 

[4G63dsm1]

I dont mean to hijack the thread but i'm having the same problem. I put a 2 1/2" downpipe with a 3" catback on stock turbo (T25) i did the free mods which included the removal of the nipple on the BCS. I went for a drive after doing all that..i put the pedal to the medal and noticed my stock boost gauge rising like it never did before. Next thing that happened..i think i got fuel cut. The car just lost power for like a second, i backed off the pedal and everything went back to normal. It kinda scared me at first but i had a feeling that i got boost spike or/and fuel cut. Now How can i fixed that problem? I heard that by having my O2 housing ported would get rid of that issue, is this true? Also i found this product on the import-tuner website and i would like to know if it would work in my case: 1992 Mitsubishi Eclipse Talon - Power Pages - Import Tuner Magazine. Scroll down to see it...is a HKS Fuel cut defender. Thanks!

 

[kenamond]

I dont mean to hijack the thread but i'm having the same problem. I put a 2 1/2" downpipe with a 3" catback on stock turbo (T25) i did the free mods which included the removal of the nipple on the BCS. I went for a drive after doing all that..i put the pedal to the medal and noticed my stock boost gauge rising like it never did before. Next thing that happened..i think i got fuel cut. The car just lost power for like a second, i backed off the pedal and everything went back to normal. It kinda scared me at first but i had a feeling that i got boost spike or/and fuel cut. Now How can i fixed that problem? I heard that by having my O2 housing ported would get rid of that issue, is this true? Also i found this product on the import-tuner website and i would like to know if it would work in my case: 1992 Mitsubishi Eclipse Talon - Power Pages - Import Tuner Magazine. Scroll down to see it...is a HKS Fuel cut defender. Thanks!

Before you do anything major like porting, I'd do the basics first. Make sure your WG system is in proper order. Check the vaccuum lines for the BCS. Make sure the WGA actually extends the arm under pressure and turns the flapper lever on the turbine housing (can do this during a boost leak test). Fuel cut is a safety measure for WGA failure, so maybe the WGA failed. The setup for the BCS is two lines that come from the WGA and compressor nipples into a T fitting with a 3rd line going to the BCS, and a final line going from the BCS to the intake pipe. If you do a boost leak test to test the WGA, you should pull the line off the intake pipe and plug it. Then you should pressurize at the compressor inlet or TB elbow up to around 11psi and see the WGA arm extend. Note where it starts to move (what pressure) and what pressure causes it to fully extend. This should happen at around 10-12psi boost test pressure.

If all of that checks out, run a vaccuum line straight from the compressor outlet nipple to the WGA nipple, cap the BCS plumbing that you disconnected to do this, and do a test run. This removes the BCS and it's vaccuum lines as potential culprits and delivers boost straight to the WGA which should actuate at 10-12psi. If you miraculously see 10-12psi boost, I'd check the vaccuum lines for leaks; something's hosed with your BCS/plumbing.

I'd be a bit suprised if your T25 was creeping, but maybe it happens.

 

[4G63dsm1]

Before you do anything major like porting, I'd do the basics first. Make sure your WG system is in proper order. Check the vaccuum lines for the BCS. Make sure the WGA actually extends the arm under pressure and turns the flapper lever on the turbine housing (can do this during a boost leak test). Fuel cut is a safety measure for WGA failure, so maybe the WGA failed. The setup for the BCS is two lines that come from the WGA and compressor nipples into a T fitting with a 3rd line going to the BCS, and a final line going from the BCS to the intake pipe. If you do a boost leak test to test the WGA, you should pull the line off the intake pipe and plug it. Then you should pressurize at the compressor inlet or TB elbow up to around 11psi and see the WGA arm extend. Note where it starts to move (what pressure) and what pressure causes it to fully extend. This should happen at around 10-12psi boost test pressure.

If all of that checks out, run a vaccuum line straight from the compressor outlet nipple to the WGA nipple, cap the BCS plumbing that you disconnected to do this, and do a test run. This removes the BCS and it's vaccuum lines as potential culprits and delivers boost straight to the WGA which should actuate at 10-12psi. If you miraculously see 10-12psi boost, I'd check the vaccuum lines for leaks; something's hosed with your BCS/plumbing.

I'd be a bit suprised if your T25 was creeping, but maybe it happens.

Can a local mechanic shop do this (Boost leak test)? And If my WGA is actually bad, what can i do to solve the issue? can i just replace it? I've personally never seen WGA sold seperatly for the T25 turbos. Thanks!

 

[Mr Peepers]

I dont mean to hijack the thread but i'm having the same problem. I put a 2 1/2" downpipe with a 3" catback on stock turbo (T25) i did the free mods which included the removal of the nipple on the BCS. I went for a drive after doing all that..i put the pedal to the medal and noticed my stock boost gauge rising like it never did before. Next thing that happened..i think i got fuel cut. The car just lost power for like a second, i backed off the pedal and everything went back to normal. It kinda scared me at first but i had a feeling that i got boost spike or/and fuel cut. Now How can i fixed that problem? I heard that by having my O2 housing ported would get rid of that issue, is this true? Also i found this product on the import-tuner website and i would like to know if it would work in my case: 1992 Mitsubishi Eclipse Talon - Power Pages - Import Tuner Magazine. Scroll down to see it...is a HKS Fuel cut defender. Thanks!

I think the first thing to do is a boost leak test- and second, get a real boost gauge to know what's actually going on.

The stock boost gauge is just a guess by the ecu at how much pressure the intake is seeing. If you have a boost leak, it will make the ecu think there is more airflow, add the proper amount of fuel, and hit fuel cut soon after. It will also peg the stock boost guess/gauge from the ecu seeing all the air being sucked through the maf, even if much of it is leaking out before it reaches the engine.

2G Turbo DSM Boost Leaks -How to test and fix

 

[Eclipsegst2312]

I have a Halman Pro Manuel Boost Controller and it worked great with my small 16g. And now still works great with my fp green. I had a turbo xs dual stage MBC and I didnt really like it. In my opinion the Halman Pro is your best bet for a MBC