98 V70 T5 Manual - Low boost on ARD Green Tune

[matthew1]

I'd agree with everyone saying look for blown off turbo hoses or loose clamps. Those are very likely scenarios. Way down on the list is... run your hand under the intercooler looking for cracks in the intercooler. Here's my blown intercooler story. It threw no codes.

[Seaway]

Sounds like I need to go in with a 10mm socket and tighten all my hose clamps. They are all T-bolt style clamps on Mishimoto silicone hoses, so I would think they would have stayed tight. I will also check the intercooler for leaks.

[scot850]

How do you know you got a 22 psi pulse? Do you run an ELM or something to know this?

What I'm not getting is what the cause of the spike, unless as suggested it is a problem with the CBV or boost valve sticking. What the other guys suggest sounds logical. If I recall the advice I was given to check the CBV is to take the pipe from the CBV to the TCV, remove it from the TCV and connect a vacuum source to it and see if it holds the vacuum.

Another possible problem could be the fuel pressure. My 2000 R is running 60 psi according to the dealer, but 43 psi is the minimum (3-4 bar).

Neil.

[Seaway]

I was watching the boost gauge as it shot up to 22. It normally sits right at 17 psi under hard acceleration.

Hopefully I will get some time to look at all this over the weekend.

[mecheng]

Is it safe for the engine to see 22psi peaks? That is almost double of the stock peak at 12psi my T5 boosts to. I guess it's pretty fun but that sure is a lot of boost and heat

[matthew1]

My stock intercooler cracked at 17-18psi, for what it's worth.

[erikv11]

I lost 3 psi from a slightly loose clamp. Triple check all the hoses.

I second, checking the waste gate action. The rod gets quite rusty and can restrict the movement. I lightly sanded it and put anti-seize to make the operation smoother.

I would also check that the CBV is working okay.

How do I pressure test the CBV? Just hook up a hose to the CBV and add pressure with a hand pump?

This will work fine, or the kind of method suggested by mecheng in his follow-up post. That is, just give it a little vacuum or a little pressure, and see if it holds. From reading your thread, right away I wonder if maybe the CBV diaphragm is torn. It's a new CBV diaphragm, correct?

[Seaway]

It is a new cbv diaphragm. I have another new one and I have the original which doesn't appear to have any tears or holes. The engine is actually a 2000 2.4L HPT from an R. It's funny, I thought about upgrading the turbo to a 19t when I rebuilt it, but decided to play it safe and just run the 16t since it is plenty of power for me.

I will pull it and swap it out and see what happens. The car did not run at 22psi for any time, it was just a quick spike.

[erikv11]

Maybe easier to just test it rather then swap it? I find it a pain to pull the diaphragm, with those pesky little bolts, don't want to send you on a wild goose chase ...

[Seaway]

Maybe easier to just test it rather then swap it? I find it a pain to pull the diaphragm, with those pesky little bolts, don't want to send you on a wild goose chase ...

I am going to test first, as getting to that bottom bolt will be tough.

I am now hearing a whistling sound when I accelerate and I was not even able to get up to the 10psi I had been seeing on my morning commute. Whatever it is seems to have gotten slightly worse. If I wasn't so busy, I would get this looked at tonight, but I don't know if I can make the time.

On an unrelated note, does anyone know what a fair price to install rear calipers and rotors would be? I have the parts, but not the time to do the work.