98 V70 T5 Manual - Low boost on ARD Green Tune

[Seaway]

I checked the CBV with a vacuum pump and it does not hold vacuum at all. I have another turbo laying around and I checked it the same way and it held vacuum fine. So it looks like I will be swapping out the cbv this weekend. Luckily I have two spares.

I am also going to have the rear brakes done, new calipers, rotors and pads. Also new parking brake pads and associated hardware. One of the calipers is sticking a bit now. Parts should be here tomorrow and my indy owes me a favor and is going to put it all in for an hour and half labor charge. This is on top of a free brake flush and fixing the wheels they scraped up when mounting my summer tires.

[Seaway]

So I swapped in a different CBV and a different CBV cover and I have the exact same results. Now I apply vacuum with a hand pump it leaks down to about 7psi and then holds there. With he ARD tune it still hits 10psi and holds and the stock T5 ecu hits 7 psi and holds. So it looks to be losing +/- 5 psi.

I tightened EVERY hose clamp on the car so there should be no leaks from clamps. I suppose it could be a hole in a hose? The only hose associated with the turbo that is not a new Mishimoto hose is the couple from the OTE pipe to the turbo.

Maybe it's the intercooler? How do I pressure test it?

The car is running very, very well, probably as good as it has run since I have had the car. Idle is rock solid and smooth and everything is very responsive, it is just lacking oomph.

[Ozark Lee]

Pressure testing the intercooler is going to be tough since, by design, it has a weep hole to drain condensation. Usually a busted intercooler is pretty obvious but then again they usually break due to slamming into a parking stop or a sidewalk at a parking lot.

...Lee

[abscate]

Perhaps removing and submersing in a kiddie pool while applying a few psi pressure to test for splits? You can cover the weep hole with some putty or gum.

Clean pool when done.

[Seaway]

Ah yes, the weep hole... The car is also making a whistling sound that is siren like. It's exciting, but I don't think it's good.

[JDS60R]

Remember what Vizzini said " Go back to the beginning"

Whenever a good check over doesn't reveal the problem - go back to the beginning. Get compression and leak down numbers. One way to get rid of boost is to let it leak past the valves or rings.

If you can't get excited about the idea that something may be broken I normally get initial evidence like this:
You can also disconnect the waste gate vacuum control line and "gently" run it up (drive it) to the boost you wanted. If it can't make the 17lbs then you know for sure you have a mechanical issue. Remember you have no boost control with the waste gate hose removed. If you floor it and hold it, the boost will rise to its mechanical limit. Usually blowing the motor. So just accelerate smoothly and hit 17psi - then pull over and reconnect the hose . ( it comes off easier on the TCV usually )

If you can hit 17 lbs then we need to look at the turbo controls (wastegate, TCV etc) . In your initial check you should have used some plastic pipe ends to plug up the intercooler piping. You use one end to block the air and the other end with a tire valve in it to allow compressed air to pressurize it.
Put it in a garage , Pressurize it and have a finger or tool ready to block off the intercooler drain. It should hiss with the drain open and be silent with the hold covered by your finger. Use at least 17 psi to check yours. You should testing - all at once the entire turbo piping. From the turbo output connection(separate and insert plug ,and clamp to seal) to the throttle body (separate and insert and clamp plug with tire valve connection. )

[JDS60R]

If its as loud as a siren then you know you have a leak - pressure test the pipping as suggested from start to end. Use 17-25 psi to test.

[Seaway]

It's not as loud as a siren, but it is throttle dependent. Makes the noise as I accelerate. Doesn't matter if I am boosting or not. I will disconnect the wastegate and see what happens.

[Seaway]

I disconnected the wastegate from the TCV and there is no change. It hits 10 psi and nothing more.

[Seaway]

Should I redo the CBV and make sure that it holds vaccum? When I insert the CBV diaphragm and spring, should the spring be compressed and in the "locked" position (held in compression by the plastic cap thingy)? I did not install it that way when I redid it the other night.