What does this do?

[Mr Pig]

On my 2017 TDi FR there is a solenoid something like this, on the bulkhead to the right behind the engine.

What does it do? What are the symptoms of it not doing it? I've been trying to track down a rattle/buzzing noise since we got the car and I'm wondering of it could be a bad solenoid.

I also found an air hose to the right of the engine that was not connected! The plastic coupling in the middle of the hose was undone. Nothing to do with the noise and reconnecting it doesn't seem to have made any difference to anything.

 

[Evoxer]

Looks like a pretty standard boost (vac) solenoid. Controls the turbo output.

Sent from my IN2013 using Tapatalk

 

[Johnny Leon]

Turbo Pressure Convertor. The pressure converter controls the EGR valve by mixing the atmospheric pressure and pressure generated by the vacuum valve in the EGR valve.

https://www.onlinecarparts.co.uk/pi...ZVzYlN6J--VbR9W9Z2yc80m5VvQ6J1TwOet0WX-bkDNhA

Cleaning solenoid :-

 

[Mr Pig]

How would you know if it is faulty? I'm at work just now so I can't watch the video. What sort of RPM does it kick in?

 

[Mr Pig]

If you disconnect that valve, will the car still run ok? If I could disconnect it and drive the car it will tell me if that's what's making the noise.

 

[black_sheep]

N75 valve. Quite a lot of info on the net - controls turbo wastegate, which impacts boost. Lost count of how many times I’ve changed these on cars with c.60-100k miles, where dealers have stated that turbo is on its way out.

Has a diaphragm inside which wears over time. Chucks up fault codes, then eventually engine warning (emission) fault, limp mode, no boost (from c.1700 rpm).

 

[Mr Pig]

What I'm getting is a rattle sound at about 2,800 rpm then again towards 4K. Sounds like it is coming from exactly where this valve is.

Dealer said it was the timing belt. I knew it wasn't but I let him change it anyway because, new timing belt! Then he said it was the turbo and changed that too. Made no difference. Don't know if that valve could make a rattling sound though?

Car does feel underpowered. It's a 150 TDi but I had a Golf with the same engine which felt a bit more powerful.

 

[black_sheep]

It’s a 10 min diy job if fitted to the bulk-head, then clear any fault codes. Only time it was a PITA was on an old A4 where the bumper had to come off to gain access.

Part cost is £45-90 depending on model.

If not functioning properly, the car will run rich - normally see more soot around exhaust exit, but this car will have a dpf. Is it regenerating more frequently than normal?

 

[Mr Pig]

... but this car will have a dpf. Is it regenerating more frequently than normal?

Yes, it has been but with it only doing short trip because of the lockdown I was assuming that was the cause of the frequent regens.

 

[Mr Pig]

This is the hose that was not connected. The coupling circled was undone and the ends were hanging lose. I have no idea what it does but it is connected to the solenoid valve. Actually, it seems like half the rubber hoses in there are!

 

[MATT RILEY]

Looks like the brake servo hose, gulp!

 

[Mr Pig]

Looks like the brake servo hose, gulp!

Can't be. No way anything to do with the brakes would be such a feeble connection and it's nowhere near the brake system. One end heads into the bulkhead and the other goes into a manifold and one of the pipes off it goes to the valve we're talking about.

It still doesn't look right. The two halves of that connector fit together, and they were right next to each other, but the flanges look like there is something missing.

I remember a time when I could look under the bonnet of a car and figure out what all the bits were doing. Today, I have no idea what half of the hoses, wires and bits of plastic are for. It's a total mess in there!

 

[black_sheep]

From the EA288 manual:

#8 Non-Return Valve to brake servo - uses vacuum as a brake booster.

 

[Mr Pig]

8 Non-Return Valve to brake servo - uses vacuum as a brake booster.

Well, that was off! And I didn't really notice the difference!!

Great diagram, thank you.

 

[MATT RILEY]

Can't be. No way anything to do with the brakes would be such a feeble connection and it's nowhere near the brake system. One end heads into the bulkhead and the other goes into a manifold and one of the pipes off it goes to the valve we're talking about.

It still doesn't look right. The two halves of that connector fit together, and they were right next to each other, but the flanges look like there is something missing.

I remember a time when I could look under the bonnet of a car and figure out what all the bits were doing. Today, I have no idea what half of the hoses, wires and bits of plastic are for. It's a total mess in there!

Looks like it was though!

 

[Mr Pig]

Looks like it was though!

Yes it was! The two ends must have been just holding together as they fell apart as soon as I touched them. Lucky escape I reckon. Could've caused an accident if that had come apart while driving.