Replaced my TCV (T5)
 

Jeremy Clarkson reviewing the 2.5-litre Focus ST in 2006.

At 130,000 miles, my T5 wasn't exhibiting the "Any gear, any revs" torque characteristics. I found myself waiting for it to accelerate through 2nd and 3rd. Almost like when a VVT cam isn't engaging. Was also recently overtaken by a completely stock MK3 Focus ST in a manner which would suggest my car had a problem.

I've had a Pierburg TCV sat in the shed for ages but kept putting it off as the job looks like a pain due to the location, however made myself do it yesterday.

ECU takes a while to adjust to the new TCV so didn't expect immediate improvements (24 hours). Upon first driving it, the car drove like the ECU had been reset i.e it felt strangled and worst on power than before. However took the car out and let the car get used to my driving style.

Next day, car is now producing the "any gear any revs" torque behavior and at high RPM I can actually hear the turbo hiss. Car feels quick again, and noticeably smoother in acceleration. It's worth noting that TCV is pretty much a consumable on these cars and there are recommendations to replace them after 60,000 miles.

The job is a bit of a pain, but no more so than replacing the cabin filter... Go in via the drivers side wheel arch area.

Tips when replacing:
- No need to remove the wheel arch liner.
- Remove the top bolt of the anti-roll bar drop link and move it out of the way for better access.
- You'll need a torch to see what you're doing.
- Unplug the connector from the TCV first before trying to unseat the TCV.
- Stick the handle end of a breaker bar underneath the TCV and lever downards to lift it from the metal prong that it sits on without any drama.
- Remove the right-hand pipe first as it's the shortest and restricts movement of the TCV. One that one is off, you can move the TCV closer to you when removing the other two pipes.

I used two 9mm 'Petrol hose clamps' to replace the quick release clamps on the two horizontal pipes. The top pipe is narrower so I just re-used the original clamp.

https://66.media.tumblr.com/2d6d1783...h83xo1_640.jpg

I experienced the same on my 139k miler 850 T5, made a big difference and restored 2-3 psi of boost (changed all vacuum lines at the same time as they were showing signs of fatigue).

Should def be a serviceable item. What mileage did your car have it's first replacement (or never) ?

From what I can tell its never been changed.

As I plan to remap mine, I believe most tuners highly advise a TCV replacement as part of Stage 0 prep.

Thinking I should probably be adding this near to the top of my todo list

Just to add my 2c, mine failed 2 years ago at around 100k.
In my case - apart from feeling of car's sluggishness, I could observe low boost and TCV duty cycle off the charts, when testing with Vida.
I am not sure if those really loose performance in time (i/e. if not broken, will it work worse just because its old? ) but for sure its one of most critical component to keep turbo piping in good condition and defo one of the cheapest to replace.

Also - worth adding - replacing CBV (that small metal valve going from turbo to piping) made quite a difference on mine.

https://www.volvoforums.org.uk/attac...1&d=1542018595

How do you view the boost info in VIDA?

You pull out few relevant parameters (see my example) depending on your liking, but most important are (A) Ambient air pressure and (B) Boost pressure.

https://www.volvoforums.org.uk/attac...1&d=1542034657

you substract the A from B and the difference (like on mine = 215hpa) converted fo PSI will give you all answers.
Along with some extra values (hence my additional parameters displayed) you can see that with fully opened throttle and TCV duty cycle at correct value, I was only achieving 3 PSI boost so there was an obvious sign of something not right.

PS - as driving&watching laptop is not something recommended, get yourself some screen recording freeware, like ICE Screen recorder or anything similar.

Doesn’t VIDA itself have built in logging/graphing so you can view data after the drive?

pretty sure it does, but I am not sure how to use it properly yet :P Still learning this software even after 2 years.

Gotcha. I’m in a similar position, hence my question rather than a statement ;)