95 855T5 won't hold boost.

[bmdubya1198]

Any word from Hilton Tuning? That's where I'd start.

Yeah, I've been going back and forth with him over the past couple weeks. We can't figure anything out. I'm thinking maybe somehow my ETM is failing and limiting boost, and I'm hoping that's the case since I have the Sacer contactless TPS kit that came with the car. I put a junkyard ETM in my car not long after I bought it and it's been working fine otherwise.
I wanted to rebuilt the original ETM, but unfortunately I stripped the threads out on the shaft where the magnet is tightened onto for the sensor. Looks like I have to pull the current ETM and rebuild that one.

[Sommerfeldt]

Did you try switching in a different TCV?

- S

[bmdubya1198]

Did you try switching in a different TCV?

- S

I've tried three so far, no difference.

[abscate]

Did you try switching in a different TCV?

- S

I've tried three so far, no difference.

Did you try switching in a new TCV?

This is one junkyard part that is often tired and worn out.

[bmdubya1198]

Did you try switching in a new TCV?

This is one junkyard part that is often tired and worn out.

The one I currently have installed is a new unit.

[ZionXIX]

Are the OEM TCVs even available to buy anymore? Fcp is not carrying them and all the parts website I've checked says they're NLA. Is the IPD unit the only option now?

[Sommerfeldt]

Just to backtrack a little bit...

If Hilton is right, the error codes have nothing to do with it. The ECU is requesting that the TCV should be closed/closing, right?
That means the ECU wants more PSI goodness, not less. So it's reading IAT values and whatnot, looking at FT and O2, and still requesting that the TCV be closed. So... that's good, I suppose.

That kind of narrows things down, though. It either has to be the TCV itself, or connections to it, be it electrical or air. Are you absolutely sure that the hoses are correct, not stuffed up with something, and fastened securely? Especially the connection to the turbo (not the WG) needs to be tight to avoid super weird behaviors.

Or, the turbo is fried. WG broken, stuck open, cracked, bent... Shaft could have play that's restricting it, overheating it, and so on. But you'd probably have other symptoms if it was in that bad of a shape.

Or, you have a leak somewhere, some hose that's just tight enough to hold ~5 psi, and then starts leaking, for example. Or a cracked IC with the same symptoms. Have you pressure tested the whole thing? I.e. plug up the bleed hole in the IC, and feed the whole thing 12 psi?

I may be full of bovine excrement here - just listing the things I would try.

- S

[erikv11]

Are the OEM TCVs even available to buy anymore? Fcp is not carrying them and all the parts website I've checked says they're NLA. Is the IPD unit the only option now?

People have used a few different Pierburg TCV's successfully, e.g. viewtopic.php?t=77474. This may work, too, but check out the connector: https://www.fcpeuro.com/products/volvo- ... o-30670449

[bmdubya1198]

I have this one, but I ordered it from eBay. http://www.ardideas.com/Turbo-Control-V ... _2180.html

[bmdubya1198]

Just to backtrack a little bit...

If Hilton is right, the error codes have nothing to do with it. The ECU is requesting that the TCV should be closed/closing, right?
That means the ECU wants more PSI goodness, not less. So it's reading IAT values and whatnot, looking at FT and O2, and still requesting that the TCV be closed. So... that's good, I suppose.

That kind of narrows things down, though. It either has to be the TCV itself, or connections to it, be it electrical or air. Are you absolutely sure that the hoses are correct, not stuffed up with something, and fastened securely? Especially the connection to the turbo (not the WG) needs to be tight to avoid super weird behaviors.

Or, the turbo is fried. WG broken, stuck open, cracked, bent... Shaft could have play that's restricting it, overheating it, and so on. But you'd probably have other symptoms if it was in that bad of a shape.

Or, you have a leak somewhere, some hose that's just tight enough to hold ~5 psi, and then starts leaking, for example. Or a cracked IC with the same symptoms. Have you pressure tested the whole thing? I.e. plug up the bleed hole in the IC, and feed the whole thing 12 psi?

I may be full of bovine excrement here - just listing the things I would try.

- S

Yes, the ECU appears to be requesting boost. After comparing the logs from my R to my cousin's S70 T5 (which is boosting perfectly fine), the TCV duty cycle is right about the same.
I checked the wiring to the TCV, perfect connections. The hoses are new and I can confirm that they are in the correct places. I'm going to double check the hose to the turbo compressor housing tomorrow to make sure it's not kinked or anything crazy. I don't think the turbo itself is the problem. The car has no problem holding boost at 8 PSI when I'm on the throttle, it just won't boost beyond that. Also, when I disconnect the WG hose, it will boost to 20+ PSI. I checked the WG arm and position and it all looked perfect. The adjustment is set perfectly to 4.4 PSI, factory spec.

I have not pressure tested the whole system, but I have checked from the rubber hose just past the over-the-engine pipe to the throttle body. That's how I found a leak in my intercooler. I pressure tested the spare I had, it checked out, so I installed it. That made no difference. I'm going to check out everything else soon.

Don't worry, I think you're spot on with these suggestions. I've been going through these different tests multiple times with no changes. I'm currently rebuilding the ETM in hopes of that making a difference, since I had the Sacer contactless TPS on the shelf already. I wanted to repair the original ETM, but the shaft is stripped out. I had to rebuilt the ETM that's currently in the car, which was removed from a 1999 C70 HPT manual. Hopefully this fixes the whining, which I think is coming from the ETM. Who knows, maybe this is also affecting my boost!