Can someone Help me please..

[InCoGNiTo]

helllo
Im looking for some help, and I assume this is the right fourm..

ill make this as breif as I can in discribing it and symptoms.

first off, my car, 1997 Tsi AWD is Stock, No powertrain modifications with the exception of I have the cat converter removed.
when I first got my car, it was reading a shade under 15psi on the my gauge (quality gauge/autometer), I would get the odd spike to 16 or so, but it always hit and held 14-15 psi.
The car worked very good, I was impressed and it pulled good for beeing in stock trim.
over the months, boost starting dropping off. over a few months it went from holding 15psi, down to 12, down to 10 and down to 8, big change in boost numbers. so after doing some tests and looking some things over I figure the turbo must be wore out, and time for replacment.
last boost reading on the old turbo was about 8psi, felt like I was driving a civic, not a talon..

So, this brings us to now, I replace my old turbo with a Brand New T25,
I used a new turbo, New gaskets, new seals, new everything in the swap..
old one came off good, new one went on even better.
So after getting it on and getting the car going and warmed up, I go for a drive, Im going easy making sure everythings ok, taking a good seat and get things flowing again.
2 days later and 600 kms later, I figure break in time is ok and everything should be ok, I finally decide to go to WOT and see how things are.
I was expecting a good pull, much like it did when I first got the car, but to my disapointment, theres nothing, it feels the same as it did when I took the old turbo off.
mind you, it does sound better ( better cleaner spooling noise, haha) but it still doesnt pull half as good as when I first got it and the boost number just arent there.
With a new turbo and other things I know I can check out ( leaks, cracks, etc) I dont know what it can be, I dont know what the problem is, but I know I want it solved.

So...
I am not a mechanic, and Im still fairly new to this dsm/turbo stuff.. I just havent gotton involed in learning alot about it, this is why I ask for help..

Why isnt my car boosting like it used to ?
Ive check for leaks, cracks and other things, I buy and install a brand new turbo and still nothing, and theres no other known problems that I know about.

what can I do, check or change to get my 15psi back, I miss it and want it back

Thanks for you time..
look forward to some replys and suggestions.

Stephen.

 

[trbotaln]

check for boost leaks. My t25 hits 15psi and then drops off to about 12.

 

[missouri_dsm]

http://vfaq.com/mods/ICtester.html
Try making one of these and use it monthly if not weekly.

 

[InCoGNiTo]

I already made one of those and tested it a few times..
ran 20 psi thought it a few times and there was no leaks at all...
I just tested it again this morning and nothing, no leaks..

im lost...

 

[missouri_dsm]

do you have a boost controller? make sure the adjustment hasn't moved.

 

[CanadianTSi]

You payed for a brand new T-25? ouch.

Have you done a compression test lately?

 

[InCoGNiTo]

there is no boost controller, so that wouldnt be a problem, shes in stock trim, no modifications at all regarding the turbo or boost. under the hood is bone stock..

Ive been talking to some people and got 2 suggestions..
1 beeing the "boost control solinoid" ? i have no idea what it does or where its at, but they told me to bypass it and check again for good boost, anyone have info on this ?
and 2 beeing the downpipe.. i was told the downpipe is a double walled pipe and someitmes the inner wall can colapse on itself causing a blockage and therefor causing "bad boost numbers", again, anyone ever hear of this ?

 

[InCoGNiTo]

You payed for a brand new T-25? ouch.

Have you done a compression test lately?

I got a half decent deal on it , personally, id rather get something new then used, there is good used turbos out there for sale, i just didnt want to take the chance and get something bad or something that wont last, with this, im safe..... i think....hehe

compressiong was tested a few months ago, it was tested when i was making low boost and all 4 cylinders came up good, so i dont think thats an issue, however, i plan to cheeck it again..

 

[missouri_dsm]

your boost control solenoid is your stock boost controller. If you want to find it, follow the vacuum hose coming from your wastegate(the canister looking thing connected to your turbo with a rod going to exhaust manifold).

 

[InCoGNiTo]

and I bypass it how exactly ?
with that bypassed is it safe to run ? or just test it like that ?

any more info before i attempt this ?

 

[missouri_dsm]

If you want to bypass it just unplug it and run the vacuum hoses together using vacuum connectors. I have heard on a 2g if you unhook the bcs it will throw a check engine light, just so you know. I personally would buy or borrow an aftermarket boost controller and try that just to be safe.

 

[CanadianTSi]

It will throw a CEL only if you totally unplug it from the wiring but that does nothing.

Just run a line from a pressure source straight to your wastegate and see if your boost holds.

 

[InCoGNiTo]

ok, i checked for and found that solinoid, to dark to play around with it tho..
ill check it out in the morning and see if I can bypass it, i think I understand how to do it.

another question, whats the stock boost on a 97 ?
ive heard 3 things today, 8psi,12psi and 14.7 psi ?
can someone tell me the actual number ?

 

[sup3rfr3ak]

i hit 15 psi and stayed their at wot all the time never droped when my 95 gst was stock , for some reason though when i first bought my 95 gst it was alot faster and quicker from 0-60 then other stock gst's around here id just tear them up i have no clue why and i still ahve yet to ever figure that out nothing that i kno of or could see or tell what aftermarket besides a k&n filter the car had 100k

 

[InCoGNiTo]

I eliminated the boost control solinoid, and no change... still not boosting good.

im lost...

 

[terefic181]

InCoGNiTo,


You' seem to have ruled out leaks and the solenoid.

Did you replace the wastegate actuator with the new turbo, or is it the old one?

http://www.dsmtuners.com/forums/showthread.php?t=139528

If you did replace it, then you may still want to check it for functionality.

Tom

 

[InCoGNiTo]

its new also..
I will check it tho. Whats the best way to check it for proper function ?

 

[terefic181]

Ok, if the actuator is new it's probably not an issue. A possibility you are looking for is if the wastegate is opening and closing properly. If it sticks or opens to soon you loose boost.

A couple of things to start with.

Is the actuator arm connected to the wastegate?
Did you check the wastegate for free movement when you replaced the turbo?


To check the actuator>wastegate: You can connect a Mityvac style hand vacuum/pressure style pump to the hose going to your actuator, and pump pressure in. The first thing you'll be looking for is that the actuator rod is actually moving, and thus moving the wastegate. The rod should also return via an internal spring to it's original location. When you've established this movement, you can then attempt to check the pressure at which the wastegate starts to open. If that ends up being substantially different than your target boost level then this could be your problem. (unlikely though with a new actuator)

Below are some additional threads with some similar problems for your review.


http://www.dsmtuners.com/forums/showthread.php?t=67034&highlight=wastegate+actuator

http://www.dsmtuners.com/forums/showthread.php?t=179062&highlight=wastegate+actuator

http://www.dsmtuners.com/forums/showthread.php?t=174275&highlight=wastegate+actuator+test

http://www.dsmtuners.com/forums/showthread.php?t=176257&highlight=wastegate+actuator

Tom