98 T5 sluggish

Z06killinsbf · Post by **Z06killinsbf** » 29 Jun 2016, 08:55

I'm new to the Volvo world but have built a couple 500+hp Mustangs and been around high hp cars my life, with that said, I picked up a 98 V70 T5 auto a while back and with the reading of how these are sleepers I feel mine is down on power. It came with a drop in K&N and I just ordered 10ft of silicon vacuum hose to do a complete replace of everything but I don't think that will fix my issue. During normal driving the car feels like a slug until about 4k rpm and then VTEC Yo kicks in and it runs decent-ish. I don't have any of this tire burning power people talk about. So is the TCV at fault? Bad BOV (CBV I now know it as)? I know people say these are highway runners but it should still have some decent pickup. I guess I need a boost gauge to make sure it's actually making boost too.

Sommerfeldt · Post by **Sommerfeldt** » 29 Jun 2016, 10:43

Hey there.

You've got the right idea - the first thing to do is make sure you don't have boost or vacuum leaks. Also remember that you don't have a BOV unless one has been installed by a PO. If there isn't one, you need to check the CBV diaphragm and spring. If you do have a BOV, then you have to make sure there's a plate blocking the CBV. Other than that...

1: Stage 0.
2: Boost gauge.
3: WG adjustment/correction
4: MBC

- S

Post by **benpineapple** » 29 Jun 2016, 10:59

My 98 V70 was super sluggish all around when I first got it. The turning point was when I decided to eliminate any/all issues with the turbo, I didn't think it was working properly (it wasn't). I installed a new TCV, and replaced all vacuum lines, under the hood, and ran a bit of seafoam through the turbo. Let me tell you, the power difference was astounding. Boost gauge was finally registering, MPG went up a little bit, and best yet: I could squeal the tires finally.

Not saying this is exactly what's wrong with yours, but that's what got my turbo working.

Z06killinsbf · Post by **Z06killinsbf** » 29 Jun 2016, 11:31

Sommerfeldt wrote:Hey there.

You've got the right idea - the first thing to do is make sure you don't have boost or vacuum leaks. Also remember that you don't have a BOV unless one has been installed by a PO. If there isn't one, you need to check the CBV diaphragm and spring. If you do have a BOV, then you have to make sure there's a plate blocking the CBV. Other than that...

1: Stage 0.
2: Boost gauge.
3: WG adjustment/correction
4: MBC

- S

Right about the BOV, I just couldn't think of what the thing was called. For waste gate adjustment what do you suggest? And any MBC should work I would assume.

I did find a K24 turbo and Japanifold at the local recycler for under $200, would that be a worthy investment?

Z06killinsbf · Post by **Z06killinsbf** » 29 Jun 2016, 11:36

Also, I was looking at the IPD HD TCV, are there any other suggestions for a TCV?

Post by **Ozark Lee** » 29 Jun 2016, 13:31

The cars really don't have a Blow Off Valve per se. They do have a Compressor Bypass Valve that returns the charged air to the intake rather than just dumping it like a BOV does. The stock Turbo Control Valve isn't terrible and changing to another modified valve won't do you any good unless the compressor bypass valve is good. At the age of an 850 most of the CBVs are bad and have holes in them which never lets them build proper boost if they haven't been replaced.

A true BOV will mess up the MAF readings since it vents metered air. It will still run and in some cases it can really be hot rodded with a BOV but that really needs to be properly mapped in the ECU tuning to work correctly.

Go back top to Sommerfeldt's first comment before you start throwing other money at it on fancy controllers.

...Lee

Sommerfeldt · Post by **Sommerfeldt** » 29 Jun 2016, 13:32

Use a cheap pump and gauge for setting the WG actuator correctly - I forget the numbers for your engine, but they're easy to find with a little searching. The K24 is probably not a good option for you right now - you MUST do Stage 0 first, and you'll need a new tune, probably a new downpipe, new coolant lines (IIRC), new oil return... but at that price, you could have it sitting until it's time.

The stock setup you've got will get you to about 17 psi with an MBC. I've only heard good things about the IPD HD option for a TCV if you want to go with that - never tried it myself, so this is hearsay.

- S

Post by **rguzz** » 29 Jun 2016, 16:09

Lots on here (RSPI, etc) and also IPD on wastage adjustment just did mine and am delighted to report as others have things spool up quickly and boost appears as it should on the standard "gauge" 850t. Did CBV diaphragm also after determining it would not hold vacuum. All other stuff as above beforehand, including a smoke test. Car feels great. Left the turbo boost solenoid alone after all the other stuff was done cause car ran so well. I would not start by replacing the boost solenoid as pointed out above. I had to replace my wastegate because of overboosting. This with proper adjustment was invaluable to the great running condition of my 850. Refer to IPD video on how to adjust, has the PSI needed for various vehicles, 4.4 for the 850.

Post by **scot850** » 29 Jun 2016, 16:23

The stock TCV is only good to about 12psi before it falters. The IPD or ARD version goes to about 20 psi. With the IPD version I keep asking them to add to their instruction for owners NOT to crank the front 'leg' all the way in. The on the narrower sides are ok to do that as they bottom out, the front one also bottoms out, but only when it crushes the gauze filter against the valve. Only turn the front leg in 3-4 turns. Yes it will feel loose but that is ok.

The guys have covered the other issues of the CBV diaphragm developing pin holes or tearing with age. Again you can either replace with stock from turbo manufacturer or IPD also do a kit with different spring rates. Again, don't necessarily go for the heaviest spring as it is not required unless you are running higher boost. With all turbos except the 19T (as on later 'R' models) this can be replaced without removing the turbo but you have to be patient.

The stock TCV gets lazy with age. Try one from a wrecker yard and see if it makes a difference. You may find stock is ok.

THEN do your waste-gate adjustment after replacing all the old vacuum/pressure rubber pipes.

Neil.

Z06killinsbf · Post by **Z06killinsbf** » 30 Jun 2016, 14:35

Excellent advice everyone, thank you for taking the time. I'll take a look at the CBV first thing. Can I hook a vacuum pump (handyvac) to it and test it at all? I am working on the Stage 0 stuff, a majority was done prior to me buying the car but I do believe it will need a PCV replacement.

Just looked up the wastegate adjustment on here (great site BTW), looks too easy so that will for sure get done. Maybe tomorrow when I rebuild the PNP sensor.

So much for this being my daily "don't work on it" car, although when I replace the struts/shocks it will get some lowering springs.