Boosting Problem

[xrobbx03]

I think I have a boost problem, whether it be a leak or not I am not sure. I have run a boot leak test I just wanted to get some feedback on what everyone else thinks could be causing this to happen. I want to get it fixed before I start my new fuel mods.

Here is my current setup.
1997 Eclipse GST
Apexi N1 Cat back
Apexi N1 Downpipe
Injen Intake
K&N Filter Charger Air filter
Greddy Type S BOV
Greddy UICP
Ported Exhaust Manifold
Supra Side Mount
I have taken out the BCS restrictor
NGK BR7ES Spark Plugs
Upraded Spark Plug Wires (really dont remember the brand)
I also Have a breather on my valve cover instead of the vacuum line into the intake


So heres my problem in the lower rpms I seem to hit boost normally (I think).
In first and 2nd gear I am seeing lower boost of about 12-13 psi. Once I start getting into higher gears 3rd 4th and 5th I will boost right up to 15-16 psi but it wont hold. It will drop down after a few seconds or so down to 12-13 psi. What is happening. Could this just be a boot leak or something else. Also the boost gauge that I have is the JDM one off of ebay, whith the nylon/plastic lines.

In the upcoming month I will be installing the following:
Walbro 255lph fuel pump (with a rewire)
Aeromotive FPR
RC 550cc Injectors
MBC (just and ebay special is this ok?)
Greddy Front Mount Intercooler
Logger
EGT Gauge
SAFC

 

[kmoore]

Well, on your boost leak test did you find any leaks? To me, atleast on my car, it will do the same thing as you wrote. The reason why you are getting even higher boost in higher gears is because there is more load on the engine, resulting in why you are getting 15-16 psi instead of 12-13. At first it almost sounds like creep, but your still on the t-25. It is possible to creep on the t-25 though. Somebody chime in if I'm wrong on anything

 

[MidnightTSI]

First you need to make sure you don't have any boost leaks. If you are still creeping after that, these could be your problems. Your O2 sensor housing could be restrictive causing the exhaust to not be able to flow fast enough for the turbo to spool to the needed rmp, or your wastegate might not be able to keep up. These are a couple of problems that I am dealing with on my Big16G right now. Also what size exhaust are your running? Is it 2.5" or 3.0"? Some solutions I have been given are to get a 34mm flapper for the wastegate. But this can also cause problems if you are running more than 20psi because the spring tension on this size flapper, along with the backpressure, cannot close the flapper at higher boost levels. You also want to make sure your O2 sensor housing is free flowing as much as possible. The best way to go would be to port the crap out of the turbine housing and smooth the flowpath to help wastegate port flow. Other than this I'm not sure this is also a new problem for me I am sure there are some other possible solutions to this problem.

 

[xrobbx03]

the exhaust is 3". I was planning on getting a new O2 housing when I did my turbo to get it all done while everything is off. But that wasnt going to be until I had all my supporting mods done. I havent done a boost leak test yet I wanted some ideas on what could be wrong beforehand. I just felt there has to be something wrong somewhere since I cant hold boost in the higher gears. Like i said in the lower gears it holds just fine.

 

[UKNOWHO]

do a boost leak test if not performed already...if any leaks are found obviously fix them because thats unmetered air... if problem persists ## focus can then move to the wastegate and o2 housing... like mentioned in a early post ## stock o2 housing can be chokin up the wastegate and not gettin rid of exhaust gases fast enuff...also if u have the turbo out make shure the waste gate flapper can open up fully meanin immediately behind the flapper arm port the hell out of the cast so wastegate can open 90 degrees wit perspective to the hole it covers

 

[xrobbx03]

If i do a boost leak test and its not that and it ends up being the 02 housing. Is that really hurting my enginer or just not allowing me to hold boost in the higher gears, meaning could that wait to be replaced until i do my turbo at some point in the summer.

 

[talontuner1997]

I think the reason is because your running the t-25. Watch your boost gauge and rpm once you get to around 5 grand the boost automatically starts dropping because the t25 is to small to keep up. I think this is what your seeing. But defenitly check for boost leaks.

 

[magnet8289]

The previous owner of my car also took out the BCS restrictor and my car does the exact same thing. It will get like 12-13 psi in lower gears and then will boost up to like 14-15 psi in higher gears. Because the T-25 is so small it seems like this would just be normal. It wont hurt your car because the stock fuel system can handle 16 psi but it might be good insurance to get that fuel pump early. Just make sure its not creeping higher than that. I just ordered a MBC for my car and am putting it on Monday. I'll let you know if that helps my car with the inconsistent boost levels.

 

[xrobbx03]

The previous owner of my car also took out the BCS restrictor and my car does the exact same thing. It will get like 12-13 psi in lower gears and then will boost up to like 14-15 psi in higher gears. Because the T-25 is so small it seems like this would just be normal. It wont hurt your car because the stock fuel system can handle 16 psi but it might be good insurance to get that fuel pump early. Just make sure its not creeping higher than that. I just ordered a MBC for my car and am putting it on Monday. I'll let you know if that helps my car with the inconsistent boost levels.

Yeah let me know. I actually have a MBC coming next week myself.

 

[MidnightTSI]

You could just wait because like the previous post said, your stock fuel is good to 16 pounds just keep an eye on it. I would try and fix the problem if I was you. I am currently having a similar problem with my car. I am also originally from Mass in the Milford area. What part are you from?

 

[xrobbx03]

if i did get a new o2 housing would it better to go external dumped? Also they are pretty easy to install right? just unbolt and bolt up the new one. I dont have to take off the turbo right?

 

[kmoore]

if i did get a new o2 housing would it better to go external dumped? Also they are pretty easy to install right? just unbolt and bolt up the new one. I dont have to take off the turbo right?

Do not do anything before you fix your boost leaks

 

[MidnightTSI]

if i did get a new o2 housing would it better to go external dumped? Also they are pretty easy to install right? just unbolt and bolt up the new one. I dont have to take off the turbo right?

Yes they are fairly easy to install and you don't have to take the turbo off. They bolt to the turbo. I would get a dumper because they usually help to get rid of boost creep.

 

[xrobbx03]

Yes they are fairly easy to install and you don't have to take the turbo off. They bolt to the turbo. I would get a dumper because they usually help to get rid of boost creep.

I might have to look into getting one sooner than i planned.

 

[magnet8289]

I just installed my MBC today. Took about 10 min to do and it was a really easy install. I bought a TurboXS High Performance boost controller *not the standard one*. It utilizes both a ball/spring and a bleeder valve controller. My turbo spools up SO much faster, holds boost a lot better all the way through redline, and my boost is dead on right where I set it. It doesn't spike at all on me. The best thing about it is that im not getting boost creep anymore. :^) I have mine tapping the pressure source from the turbo NOT the BOV line. If you tap from the BOV line, it is more prone to spike than if you tap it at the turbo housing. I would recommend doing yours at the turbo housing. Theres a really good article in the tech section under turbo/intercooler if u need help installing it. Good luck.

 

[selmerguy]

You dont have a problem at all. The turbo is doing exactly what it should do with a direct vac hook up to the wastegate. The boost goes down because it is a t-25 and you have stock cams. The stock cams tucker out at 6 grand so with a direct vac setup it just makes you loose a few psi. You wont hurt your motor this way. and it is not creep becase if it was it would get higher not lower. Good luck and happy boosting.

 

[kenamond]

I agree with selmerguy. The T25 turbine can't flow to high rpm; that's the problem with a small A/R turbine housing: spools up quickly, but peters out in the high revs.

I don't think you should be running 15psi without a logger, though. You'll need one soon anyway. Some cars have no problems, and others can, and a logger will let you know how your car is doing. If you can stand it, run a vaccuum line straight from the compressor outlet to the WGA and cap the BCS bleeder line that hooks to the bottom of your intake pipe (cap the nipple on the intake pipe). That'll hold boost at 9-10psi until you get your MBC. Takes about 5-15 minutes depending on the person and the angle of the hose clamps . Then you can dial in 14psi on the MBC, get a logger, then see if you can go higher while you're waiting on the new turbo.

I'd like to hear others' opinions on pulling the stock O2 housing without dropping the turbo. I'm pretty sure it's impossible to get at one of the nuts between the O2 and the block. At least that's what I recall.

You're not creeping, don't port your T25 unless it's for practice before tearing into the real deal (new turbo).

Also, do you know the collector size on your ported exhaust manifold? If you didn't also port the T25 to match, that won't help with high rpm boost at all.

I recommend the boost leak tester design in the turbo tech article section (not the one in the intake tech section) - the one with the gauge on it. Makes solo-boost leak testing a breeze.

 

[oldman]

First you need to make sure you don't have any boost leaks. If you are still creeping after that, these could be your problems. Your O2 sensor housing could be restrictive causing the exhaust to not be able to flow fast enough for the turbo to spool to the needed rmp, or your wastegate might not be able to keep up. These are a couple of problems that I am dealing with on my Big16G right now. Also what size exhaust are your running? Is it 2.5" or 3.0"? Some solutions I have been given are to get a 34mm flapper for the wastegate. But this can also cause problems if you are running more than 20psi because the spring tension on this size flapper, along with the backpressure, cannot close the flapper at higher boost levels. You also want to make sure your O2 sensor housing is free flowing as much as possible. The best way to go would be to port the crap out of the turbine housing and smooth the flowpath to help wastegate port flow. Other than this I'm not sure this is also a new problem for me I am sure there are some other possible solutions to this problem.

He doesn't have boost creep, what he has is the typical T25 spike -> settle to setting -> drop off at 5k+rpm. Normal like selmerguy, kenamond and talontuner1997 already posted.

 

[xrobbx03]

thanks for the help. I am slowly on my way to upgrading the turbo anyway.

I just ordered a datalogger and also a Greddy 24r FMIC

I just installed an aeromotive FPR to get ready for my new injectors and 255lph that i will be ordering soon along with finding an SAFC2

Then i have a MBC that i havent had a chance to install yet.

After i do all of that I am going to try and tune the t25 to its max until i order a evo big 16g

 

[oldman]

I just ordered a datalogger and also a Greddy 24r FMIC

Make sure you follow the FMIC install up with a thorough boost leak test.

I just installed an aeromotive FPR to get ready for my new injectors and 255lph that i will be ordering soon along with finding an SAFC2

Make sure you Taflon both the vacuum fitting and adjustment rod on the AFPR, they are gaurrenteed to leak right out of the box.

Then i have a MBC that i havent had a chance to install yet.

Make sure you source your boost reference for the MBC from the compressor housing and not the BOV line, regardless what the MBC instructions tells you.

After i do all of that I am going to try and tune the t25 to its max until i order a evo big 16g

Don't, anything above 17psi, the T25 will mostly be blowing hot air.....mostly.

 

[xrobbx03]

thanks for the tips. I did teflon the vacuum line fitting but not the adjustment screw on the fpr i will have to go back and do that.

 

[kenamond]

thanks for the tips. I did teflon the vacuum line fitting but not the adjustment screw on the fpr i will have to go back and do that.

Don't get sprayed in the face with gas.

 

[oldman]

Don't get sprayed in the face with gas.

I would hope that he doesn't have fuel on the air chamber side of the AFPR.

 

[kenamond]

I would hope that he doesn't have fuel on the air chamber side of the AFPR.

It's been a while since you embarrassed me Bruce.

Mack

 

[oldman]

Sorry Mack.