V50 Engine 2.0D : Increased fuel consumption

[daroo]

with vacuum it work so it means that both throttle valve membrane are not broken. The common problem is the Adjuster rail / gear worn out, you can find repair kits on ebay.
Let us know if the problem was just that loose hose

[IainG]

Hi
The vacuum system is actually quite easy to check and work on.
https://www.volvoforums.org.uk/showt...errerid=116256

Just "T" in a vacuum gauge to check you actually have a generate a full vacuum. You could then run a temporary vacuum hose to each actuator to check they all actually operate. If they all work when tested the only other thing is the control signal and the actuator for each valve.
It would help narrow things down.

Post 2 shows the diagram

https://www.volvoforums.org.uk/showthread.php?t=334835

[Teddy1975]

At first I hoped that the problem was solved by fitting a new vacuum line, but that wasn't to be. The Engine System Maintenance message no longer appears and the car doesn't go into limp mode when I go on the motorway, and the fuel consumption seems okay, but it regens for every 140-150 km I drive which absolutely kills the mileage and will likely decrease the life span of the new DPF filter that was fitted last autumn.

I checked the valve flaps in the throttle body again and the one that's normally open, the one that comes from the intercooler, works as it should as far as I can tell. When I push on it with my finger, I can immediately feel the spring-like tension and it moves when I apply a little more pressure to it while still feeling firm and springy, and will close when the pressure is relieved.

The other valve, on the right when looking at the motor from the front, is quite different. I can feel some play in it and the flap moves just by tapping on it with my fingertip and it doesn't spring back to being closed as I would expect it to and like the other does. If I apply a little more pressure, as I did with the other flap, it will snap open a little more, and stay open in that position.

It's hard to explain in words, so I've tried to make a short video of it so someone can hopefully tell me whether it's faulty or if theirs operate in the same way.

Thanks a bunch,
Teddy

[Teddy1975]

I watched this video and although it isn't exactly the same throttle body, the principle is the same. I opened mine to have a look at the internals and the thread on the actuating rod is gone just like in the video, but unfortunately there is also damage to the thread on the flap shaft, so I can't just buy a repair kit like this from ebay as that doesn't include the shaft.

Instead, I'll order a complete used throttle body from a breaker in Sweden as there doesn't seem to be any in Denmark who has one. I'll report back once I've got it fitted to the car.

Thanks a bunch for the invaluable help guys,
Teddy

[daroo]

I confirm that it's worth changing the entire throttle body because even by changing the gears, it's difficult to reassemble it due to the brittle plastic. I had to secure it with zip ties, but it didn't work well. been there, done that!

[Teddy1975]

I find that it often helps using a hair dryer on older plastic parts, to soften them ever so slightly, before trying to take them apart. Of course, there are places where that isn't possible.

The secondhand throttle body I've ordered is now 500 km closer to me, but still needs to go another 1000 km before getting here.

[Teddy1975]

I received the secondhand part today and of course it wasn't just plug'n'play. There was play in the same valve as mine. Although not as profound, it was still more than I was ready to accept. The car it came from had driven 240k km.

When I opened it, I could see three of the teeth on the piston gear were starting to wear, enough that the valve could open about 5 mm when it was supposed to be shut. What genius decided it was okay to use ABS plastic for this purpose?

A quick measurement told me the pistons on both valves are the same, so I removed the unbroken one from my throttle body, using the easiest way by breaking the gear off the shaft so I could pull out the piston. I couldn't tell how it is possible to remove the shaft from the valve that's normally open without using some kind of violence that will destroy the valve and render the throttle body useless.

Regardless, I installed the freed piston in the newer throttle body and there was no play at all in the valve once I got it fully assembled. I've only driven a short trip of 25 km since I installed it, but the car seems chipper enough, at least no error codes or judders for now. I think the best way to tell if the problem is sorted is to see how long it'll be until the next regen.

I'll report back when that happens.