Its worth a try cleaning out your BPC, other than that check your intercooler piping

 

Just realized I had two threads on this issue, I like this one better.

Here is what she is doing: (stage 3 ecu now)





pretty consistent. Either low boost to start, or it goes to full and rolls off down to ~10psi.

Could my BPV/BOV be leaking? It is not making any noise. Re-examined hoses today, they look pretty good.

Also, could it be the MAP sensor?

Tested a junk yard BPC, that one was stuck shut and would only boost to 10psi in all gears.

Hmmm..... Help? I dont know what to change next.

 

Which BPV do you have? If stock, that may be the issue.

 

stocky stock.

 

i had this issue once where i used the white plastic vacuum line that comes with the boost gauge and it was ran around a corner a little too tight... it cracked right at the fitting and the only way i found it was while i was under the hood while the car was running... maybe check that out too... or take the time to go through and change all of your vacuum lines to silicone and see if that helps?

 

I have that clear plastic line that came with the boost gauge, I will inspect it closer and/or replace it.

 

With the LPT intercooler, it's likely the ECU freaking out.
or.. you've realized that the t25 is a crappy little turbo.
OR... you're spiking with the bigger d/p, and then the turbo's fizzling out.

What do you get for a vacuum reading @ idle?

14-18inhg?

FWIW, my t25 spiked to 19psi around 2400RPM, and was down to 13psi by 4k
..still made 230HP till redline, though, with the stock HOT IC

 

I should grab me an IAT gauge... or get a canbus and read it off of there.

 

I use my obdII logger
I got it for the Galant, and it's proven QUITE useful with the saabs

 

-18 at idle, -20 at deaccel in gear.

I had this problem with stock boost levels (the fade that is), so I dont think its just the crappy intercooler (next on my list) or the turbo.

 

those videos look pretty normal to me.....

 

18in is perect for idle.
No vacuum/boost leak there, unless you have a leak that only shows @ higher boost numbers.

 

Replace the line from BPV-boost gauge. Turned around the BPV for fun, same results.

 

mine does the same thing. peaks and drops. i only have the stock gauge though. but sometimes it peaks and drops almost back to the white on the stock gauge... any ideas? i just changed the turbo a few weeks ago, and i have the viggen ic. also have v2 dp and open intake.

 

tried a new DIC, same results.

I can get it to only boost to 6psi sometimes... awesome.

 

http://www.saab9000.com/procedures/electrical/ecu/trionic_repair.php

Worst case scenario?

 

well, i know he said he just got a new tune, and the problem was happening before the tune, but i dont know if he retuned the ecu he had, or got a separate core sent to him

 

I gave him the stage 3.. Jessop tuned it.

I have 2 ecus, both fade.

My thinking... (Try to follow...) Your first ECU fried your BPC. You replaced the BPC... ECU fried that one as well... Therefore when you installed your 2nd ECU... it still dealing with a fried BPC. Makes sense?

PS. Don't you have 3? Stock, Stage3, and some untuneable ECU that granite has?

 

I have 2 ecus, both fade.

 

Since you have a t25, just remove the wastegate hose.
The most your turbo will make is about 19psi, and then fade off. I ran the 9-3 that way for about a year with no ill-effects. I had realized that the MBC couldn't raise the boost anymore than the 19psi, so I just chucked it

This will immediately remove the ECU/BPC as suspects.

While you're down there, just check if the pin that holds the wastegate arm, and lever is there, and holding the two together.


PS: I just watched the video.
seems pretty typical of a t25 with 3" exhaust, to me.

 

What I find non typicle is that after a pull in 3rd it will fade to say 10 psi, the come on in 4th at 10 psi and continue fading.

 

pulled the line off the wastegate.

peaks to 19/20psi, seatles to 15/16psi for the most of the pull (slightly fades at end) and then will grab 15/16psi for the next gear.

So, if this unpluging the wastegate line solved it, was it the BPC?

 

not really.
It's either the BPC or ECU, now.

there's only a couple ways to test, really.
get a new BPC, or ECU, and toss 'er in.

assuming the car is healthy, just run it without the line.

 

i am voting BPC...

anyway, with the hose off, peaking to 19psi in 2nd (settling at 15/16ish) is wicked and I like it.

 

I would not be running around with the wastegate not doing its job. You could very well run lean and burn a hole through your piston.

But it sounds like a weak wasategate. Your only gettin 15-16 psi with it unplugged? It should be shootin into 20+ psi..

I would question the wastegate before the BPC.

 

The good thing about the t25, is that you run out of turbo, before you run out of fuel.

Again, assuming the car is running well, and the car wasn't pulling boost because of knock, you should be fine to run the car without.
The ECU will control knock with timing, if it can't control it with boost.

You have to use your own judgement on this one.