Boost and Wastegate Issue (t25)

[Spanky_DSM]

My car is running extremely rich with horrible gas mileage. T25 is in good condition.

I did a wot pull and it peaked to only 15psi with no boost source connected to the wastegate.

So i did a boost leak test up to 20psi with no leaks with the wastegate unhooked, then did a second test with the wastegate hooked up to a boost source and still held 20psi.

Shouldn't it have only boosted to wastegate pressure and not held 20psi?

My car feels powerless. Everything is stock besides exhaust, intake, and 1g bov.

What would be the cause for the car not building more than 15psi at wot with the wastegate unhooked to a boost source. I hear a loud wooshing noise, like a boost leak but doesnt have any. Im still running a Recirculated bov.

 

[Spanky_DSM]

With the cam gears aligned, it put the crank just where you see it.
I thought people would of know, thats with the cams aligned so i didn't bother putting it up.

Let me upload it

 

[Rock2610d]

Did you find the issue, mine does the same thing, no boost leaks and I even sprung for a evo x bov.

1995 eagle talon tsi
9:1 compression
Mls head gasket
ARP head bolts
Evo x Bov
Aftermarket forged pistons
Eagle rods
Upgraded lifters with bigger hole
Elevation=7800 ft
NGK spark plugs new
NGK wires new
Timing adv varies between 4 and 7 degrees at idle (780 rpm)
All else stock
Boost maxes out at 7 or 8 psi

 

[Spanky_DSM]

I still havent found the issue... Its been getting worse.

I recently purchase v3 link from a member and should have a log up soon.

One thing im suspecting right now is that, when i pulled the spark plugs i didnt tighten them too tight as i dont want to strip the threads and thinking maybe it could be losing compression ?

 

[Rock2610d]

Please keep us informed....I am very interested in what you find as to the cause of the low boost.

I would think un-tight plugs would be a good cause, but you should be able to see the results on the plugs and boots, if exhaust was coming out of the plug holes. You may not be able to detect compression loss....but the combustion process is a much higher pressure and that would be evident.

 

[c2ypt1c]

I still havent found the issue... Its been getting worse.

I recently purchase v3 link from a member and should have a log up soon.

One thing im suspecting right now is that, when i pulled the spark plugs i didnt tighten them too tight as i dont want to strip the threads and thinking maybe it could be losing compression ?

When my actuator took a dump, my t25 spiked up to 25+ psi instantly. It sounds like you have a preturbine exhaust leak but I would do a compression test first and foremost to rule out any internal problems. Just to clarify, you're not getting any breakup or misfires (shudder/sputtering, etc), right? How bout shaft play on the turbo?

 

[Rock2610d]

Yah, I am leaning toward waste gate acculator. Strong enough to hold 15 psi with out the boost hose hooked to it, but fails after that. With boost hose 8 to 9 psi. In my case it could be a bad boost control solenoid.

 

[Spanky_DSM]

When my actuator took a dump, my t25 spiked up to 25+ psi instantly. It sounds like you have a preturbine exhaust leak but I would do a compression test first and foremost to rule out any internal problems. Just to clarify, you're not getting any breakup or misfires (shudder/sputtering, etc), right? How bout shaft play on the turbo?

No misfires, car sounds healthy but feels like im dragging a trailer behind me. Its not driveline drag as i put the car in neutral and keep a steady speed.

I also hooked up the turbo to wastegate line directly and boost managed to continue to hit 15psi.

Still waiting on link, and will post up a log asap.

 

[Rock2610d]

^^^^seems odd as the OEM wastegate acculator should only hold about 8 to 9 psi. The boost control solenoid bleeds boost to attain the factory 12 or so psi. Hooking directly to turbo nipple then to acculator bypasses that and you should only see 8 to 9 psi max boost.

Unless you have a non-factory wastegate acculator. I disconnected my line from boost control solenoid and plugged and also got 14 or 15 psi. This confirms to me no boost leaks at 8 or 9 psi.

In my opinion the only 2 things it could be is the wastegate acculators are weak and are dumping early....harder for them to do this with boost line from boost solenoid disconnected.

Or the Boost control solenoid is defective, and letting full boost to waste gate acculator.

I am leaning towards the waste gate acculator due to the fact that we only see 14 or 15 psi max with boost line disconnected. We should see more even though its too much. I would expect around 20 with boost line disconnected. Weak springs in the waste gate cannot hold more than 14 or 15 psi.

Here is my reasoning.....with boost line hooked up we see 7 or so psi....its a 8 or 9 psi waste gate. 7 psi boost plus 8 psi waste gate is 15 psi....so it opens at 7 psi boost with the boost line hooked up. In addition with boost line disconnected it opens at 15 psi....the same as with boost line hooked and adding pressure. WE HAVE BAD WASTEGATE ACCULATORS I BET

I am going to wire the wastegate shut so the exhaust pressure cannot push it open.....this will confirm the weak springs in wastegate or not.

†************update*******
Waste gate wired shut!

Wow!
Boost hit 18 psi before 4000 rpm and I backed off! And I am at almost 8000 ft of elevation.
With my car the culpert is the acculator.
This car is a beast with the correct boost
Hope this helps you.

Good luck

 

[Rock2610d]

*************UPDATE #2*********

Actuator is NOT bad. It just needed adjustment. On a T-25 you cannot shim because the bracket is on wrong side. Shimming would only weaken the force pulling on the wastegate.

I bent the bracket back about 1/2 to 3/4 of and inch and hooked up the arm and boost hose from the Boost Control Solenoid. Tops out at about 13 psi and then levels out at 11 to 12 psi. PERFECT in my opinion for a stock setup. Especially for my elevation.

 

[Spanky_DSM]

Just giving an update and marking this thread resolved.

Its been know that 1g bovs leak at idle so i went ahead and gave a crush just to prevent that regardless if im recirculated.

Gave it a pull with the waste gate unhooked to a boost source i reached 16 psi instead of 15.

Gave it a deeper crush and now my t25 spikes up to and past 20 psi so problem solved.

Boost controller hooked up and running a steady 15psi with a quicker spool.