Air box flap solenoid

[Dave_M]

Car went in for a service last week and as part of that I asked them to swap the air box base with one I bought off this forum (from someone who had a new one fitted but turned out to be misdiagnosed and there was nothing wrong with the old one). I also asked them to test the solenoid (and replacement flap mechanism) were working.

Just been out to test this morning with VAG COM running an output test. For the airbox flap I'm not hearing anything happen - whereas for the intake manifold flap test I hear (and see) the valves operating until they run out of vacuum, but even then I continue to hear the solenoid clicking.

I'm therefore guessing the air box flap solenoid isn't working. Can somebody confirm that I should be able to hear this solenoid clicking in a similar way to the intake flaps solenoid?

Thanks
Dave

[sonny]

Stupid question but is the vacuum hose been fully reconnected to the solenoid? Not sure about the clicking , its a test I have not yet done.

[Dom81]

If you remove the top of the airbox and run this test, you should be able to see the flap move

http://www.rs246.com/index.php?name=PNp ... ic&t=77235

[Dave_M]

Ok - will have to pop the snorkel off tomorrow and have a look - can then check the vacuum pipe is on properly and also see if the flap is moving ....... Though as there's no noise at all I can't imagine it is.

Dave

[R7ANO]

I've just replaced my solenoid today! As it was stuck closed!
I tested the flap by taking the vac pipe off and connecting a hand vac pump to it to test the actuator.
The flap work perfectly so brought a solenoid today and all works fine now.
I can't tell if the solenoid clicks over the noise of the flap, sorry!
the solenoid was £55 Inc vat.

[Dave_M]

Popped the snorkel off today and there's absolutely no movement from the flap. Nor is there any clicking of the solenoid. With the intake manifold flaps, I can clearly hear the solenoid clicking once the vacuum has run out and the actuator is no longer operating.

Back to the dealer again......

Dave

[Dave_M]

OK - update. Took the car back to the dealer yesterday. They hooked it up to the diagnostics and appeared with a printout of the engine ECU fault codes...... Once I'd explained that an inoperative air box flap did not throw up an error code, and had told them how to test the flap using the Output Test, they confirmed the flap is not working. (thought maybe I should present them with an invoice for my time for training their staff at this point!!).

As I had them swap the air box base last week (when I also asked them to check the solenoid was working - which they presumably didn't do), my suspicion lies with the solenoid. The dealer's response was that I could be looking at up to 2 hours diagnostic time to check fuses / wiring / remove headlight for access etc etc, or I can take a risk and they order and fit the solenoid alone and hope that fixes it. As I don't want to give an open cheque book to the dealer (and given my confidence in them is somewhat dented), has anyone had anything other than the air box actuator or the solenoid fail on this system? I would take it elsewhere, but as they charged me £90 +VAT last week to fail to fix the problem, I'll be having that as a credit towards the cost of fixing this again.

Thanks
Dave

[adsgreen]

No idea and just thinking aloud, but can you pop the vacuum pipe off solenoid and re run the test?
Should be able to determine if there is a vacuum or control problem or not and if it's fine then it's got to be solenoid.

Wiring and fuses? if it's vacuum operated then I wouldn't have thought there'd be any wiring and such. Sure you may have a couple signal wires for the ecu but that wouldn't stop the flap opening.

I'd actually look at taking it to another dealer.

[neckarsulm]

Dave, have you read my guide here?

http://www.volkswizard.com/airbox.htm

You mentioned that they have you a print out of fault codes and while the flap doesn't log a fault a lack of vacuum can and the flap needs vacuum to work so can you post the fault codes?

[Dave_M]

neckarsulm

They didn't give me the print of the fault codes (though I could extract them myself). From memory I think one was a seconday air pump fault. I know there is vacuum being generated as the intake manifold flaps are working fine under the Output Tests.

I did try to follow your instructions about a month ago - but got stuck trying to get the connectors off the coils, and ended up breaking one of the tabs off a connector. That was the point I gave up and put it back together! Might have to have another try when I've got more time to mess about with it.

Your guide mentioned you should be able to hear the solenoid operating - mine definitely isn't clicking. I can't see why the wiring and / or fuse would be at fault - unless the solenoid had failed and drawn excessive current to pop the fuse. If this logic is right then I probably need to try swapping the solenoid next and see if that fixes it.

Dave

[R7ANO]

This is the problem with main dealer mechs, they don't know how to find the problem if there's no codes!
It's not a big job at all! Test the flap actuator with a hand vac pump it will move if it's good.
Then do the output test and check the signal on the plug that's on the solanoid, if it's getting a signal it's the solanoid that is a fault.
I think the solanoid collects moisure in it as it's the lowest point of the vac system and then causes it to stick.

[Dave_M]

Just to update on this one - car went back into Audi last week for a replacement solenoid, and the flap is now working properly. For info, you can hear the solenoid clicking once the vacuum's run out and the actuator has stopped moving - so if you've got a dead flap and can't hear any clicking when you run the output test, chances are your solenoid's dead.

Dave

[neckarsulm]

For info, you can hear the solenoid clicking once the vacuum's run out and the actuator has stopped moving - so if you've got a dead flap and can't hear any clicking when you run the output test, chances are your solenoid's dead.

Makes sense as solenoid runs on 12v rather than vacuum
When the flap and the solenoid are working there is a different sound to when just the solenoid is working but with a dead solenoid but good flap, as you say there woul be silence!
Glad you got it sorted in the end

[MB2]

Is there a reason they use 12v solenoid & then vacuum rather than connect a 12v motor directly to the flap as surely would be more reliable ?

[Dave_M]

Good question - same for the manifold flaps and exhaust flaps. Also would save the problems of trapped or leaking vacuum hoses.

Dave