Am I right in thinking that the vacuum box is on it's way out when it starts buzzing?

Ive read a few people say once it starts buzzing they have started to get boost problems.

Others have said they have buzzed for donkeys and had no issues.

so its hard to tell really, mine doesnt make any noise so im guessing its working as it should.

Well i was getting some boost and braking issues around brands hatch. Replaced the vacuum box with a second hand one, which was quiet last week, but has just started buzzing

Hmmm... So possibly somthing els damaging them or you've been unlucky with the second one failing so soon.

No idea tbh. What could cause damage to them?

Buzzing all the time or just noticeable for a few seconds when switching off?

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It was buzzing while the car was running

Hmm so, it seems the issue is continuing. Carried on vibrating/ buzzing for about 30 seconds after turning off the car. Just as I got my phone out to record it it stopped

Edited 18 February, 201610 yr by Dark_Hero

I would say check your vacuum hoses.

The three solenoids in the vacuum box control the ASV, EGR valve and the VNT actuator.

I'm probably betting two of those three are now redundant. Where as the EGR has probably been mapped out I doubt the ASV has. Have you bunged the end of the pipe? It would seem with the running on after the engine has stopped this would tie in with ASV operation (on a ASZ anyhow). The system will still try to pull vacuum down that line, I'm just wondering with it being blanked the solenoid ends up working overtime and then gets noisy.

The three solenoids in the vacuum box control the ASV, EGR valve and the VNT actuator.

I'm probably betting two of those three are now redundant. Where as the EGR has probably been mapped out I doubt the ASV has. Have you bunged the end of the pipe? It would seem with the running on after the engine has stopped this would tie in with ASV operation (on a ASZ anyhow). The system will still try to pull vacuum down that line, I'm just wondering with it being blanked the solenoid ends up working overtime and then gets noisy.

Interesting theory as most will have blanked them off by now. Possible other affects?

Which vaccum pipe is the egr valve one? I have a micro filter on one of mine

The micro filter will probably be on the intake that would normally go onto the air box.

The three solenoids in the vacuum box control the ASV, EGR valve and the VNT actuator.

I'm probably betting two of those three are now redundant. Where as the EGR has probably been mapped out I doubt the ASV has. Have you bunged the end of the pipe? It would seem with the running on after the engine has stopped this would tie in with ASV operation (on a ASZ anyhow). The system will still try to pull vacuum down that line, I'm just wondering with it being blanked the solenoid ends up working overtime and then gets noisy.

 

I think that wouldn't make any difference.  When there's an ASV on the end of that vacuum pipe, it's still a dead end, there's just a vacuum diaphragm at the end instead of a blank.

The micro filter will probably be on the intake that would normally go onto the air box.

Pretty sure that's an outlet for excess,only goes into air box to stop it making a noise?

Disconnect the ASV solenoid to see if the buzzing stops, simples.

The three solenoids in the vacuum box control the ASV, EGR valve and the VNT actuator.

I'm probably betting two of those three are now redundant. Where as the EGR has probably been mapped out I doubt the ASV has. Have you bunged the end of the pipe? It would seem with the running on after the engine has stopped this would tie in with ASV operation (on a ASZ anyhow). The system will still try to pull vacuum down that line, I'm just wondering with it being blanked the solenoid ends up working overtime and then gets noisy.

Thanks Ross,

Yes the egr has been deleted and both pipes which ran to the egr have been blocked off.

The egr has been mapped out since 2012, so seems odd that it only started happening

Disconnect the ASV solenoid to see if the buzzing stops, simples.

How would I do that? Just unplug the vacuum pipe?

How would I do that? Just unplug the vacuum pipe?

 

I mean electrically isolate it, N239 valve should have a 2-pin plug you can disconnect with red/blue and blue/black wires to it.

I've seen people delete them almost and just run the Mk4 golf type with only two pipes I think?

The micro filter will probably be on the intake that would normally go onto the air box.

I still have the one going to the airbox, and then have the micro filter on the vaccum box. I have actually paid much attention too it as the previous owner fitted it.

Last post here might interest you.

http://www.briskoda.net/forums/topic/367163-gtb2260-build-fabia-vrs/page-2#entry4528997

The buzzing is likely caused by a failing solenoid since solenoid opening is controlled using a PWM output from the ECU.

You can't disconnect a single solenoid that they are all in one unit with one plug. You could de pin the plug to stop the input signal.

You can't disconnect a single solenoid that they are all in one unit with one plug. You could de pin the plug to stop the input signal.

 

Skoda current flow diagram shows each solenoid in the vacuum box has its own internal 2-pin connector. Maybe the box is hard to open.