Possible 1.8T DV problems

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jiffi77

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Hi, keep getting the following fault code when on my A3 1.8T :-
17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction
P1200 - 35-00 -
Would this suggest that the DV has failed ? It does make a noise when I let off the throttle, but I'm unsure if it's a fluttering type of noise. The car is a standard 1.8T with 97K on the clock. Any herlp greatly appreciated.
 
Out of interest How are you getting the fault code- VAG-COM?

My DV had failed and was making a fluttering noise when lifting off the accelarator in hard accelaration (2nd/3rd). I got it checked by a mate and the DV was broken (wasn't holding a vacuum)

My DV still makes a very slight noise when lifting off but it's a more solid whoosh than a broken fluttering kinda whoosh.
 
The fault code is retrieved using VagCom.
The noise mine makes tends to be in the lowew gears when the engine is not reved very high (3K rpm) then you let off the throttle, can't work out if it's a fluttering type noise or not, will try and confirm if the noise is constant or broken.
 
Noise is kind of like a "chakka-chak" as turbo speeds down as it vents through the leak.
 
It's a very difficult noise to try and explain- all I can say is now mine is changed the slight noise is still there but a constant air rush rather than a broken air rush fluttering. Turbo starts kicking in at just over 2k, take it up to 3k and let off.

I also think my turbo whistle is more noticible and is working much better (so it should be) - a broken DV will cause shockwaves to get through and stall the turbo blades- so my VW mechanic mate told me.

I'm thinking about getting VAGcom (just to read the fault codes)- presumably the version downloadable from ross-tech is limited to what it will allow you to do?
 
Yeah, i think it's more responsive now higher up the revs range 3, 4 ,5rpm. The turbo also seem to be working better/harder/louder (I dont think it's all in my head!!). My DV was definitely broken since my mechnic mate checked the vacuum on it (it wouldn't hold one- therefore there was a split in the diaphram and it was letting air through back in to the turbo when it shouldn't have been).

the bit was about £30 from audi and took 5 mins to fit (only two clips to loosen).

generally most recommend getting a proper metal forge motorsport DV since these last forever and are piston driven as opposed to plastic and diaphram driven.
 
Jiffi,

The N249 is an electrically controlled solenoid valve, which controls the vacuum going to the top of the Diverter Valve. So effectively, the ECU has some control over whether the DV is open or closed.

On my BAM engined S3, this valve sits on a mounting bracket on top of the engine. On A3 1.8T's, and for example on our 180bhp Golf, it's located underneath the lower engine cover - where your oil dip-stick is. So underneath that cover and metal bracket.

So based on the error code, I would replace the N249 (about 30 quid) and perhaps check your DV.

AL
 
Just some added info from the workshop manual...


"
◆The mechanical air recirculation valve is in front of the exhaust turbocharger. It is opened by vacuum pressure with overrun, idling and partial load. This reduces the present boost pressure in front of throttle valve. The turbocharger is thus kept to a high speed.
◆ In vehicles with electronic throttle the mechanical air recirculation valve is controlled via the recirculation valve for turbocharger -N249.
◆ Check the air recirculation valve if the engine is not producing full power, or jerking when the throttle is opened and closed"

So you need to check if you have an electronic throttle or cable based throttle.

AL
 
[ QUOTE ]
Just some added info from the workshop manual...


"
◆The mechanical air recirculation valve is in front of the exhaust turbocharger. It is opened by vacuum pressure with overrun, idling and partial load. This reduces the present boost pressure in front of throttle valve. The turbocharger is thus kept to a high speed.
◆ In vehicles with electronic throttle the mechanical air recirculation valve is controlled via the recirculation valve for turbocharger -N249.
◆ Check the air recirculation valve if the engine is not producing full power, or jerking when the throttle is opened and closed"

So you need to check if you have an electronic throttle or cable based throttle.

My A3 1.8T is a face-lift model (X reg) so I think it has "fly-by-wire" throttle, so do you think the N-249 valve is the most likely cause ?
How easy is it to test the DV.

Jeff.
AL

[/ QUOTE ]
 
Jeff,

Its probably best to test the DV first.

A simple test is to:-
1) remove the DV.
2) Push the diaphragm within the DV up using a screwdriver.
3) When the diaphragm is up, cover the vacuum nipple on top of the DV with your finger. Does the diaphragm stay up, or does it come back down? If it holds in position, the DV is probably ok.

There is more accurate testing that can be performed, but you need a vacuum pump for this.

With regards to the N249. I think you are actually lucky that a fault code has been reported. A lot people, like myself, have various niggling performance problems with no fault codes reported at all.

Do you have VAG-COM? Or does a mate? What you can do with this is briefly test the actuation of the N249 by peforming what VAG-COM calls output tests, and what Audi call "Final Control Diagnosis". This sequence of tests basically actuates all the solenoid type valves on the car, e.g. activated charcoal filter, N75, N249, injectors and others. So what you could do is skip to the N249 test, and listen if the valve is clicking or not.

The official test is to locate the N249, disconnect all vacuum pipes from it, but leave the electrical connector connected. Attach a test piece of hose, start the final control diagnosis on the N249, and blow down the hose. You should feel air coming out, then not coming out, of the unconnected hose nipples, as the valve opens and closes.

After that its, testing voltage supply to the N249 and then wiring loom checks.

If I were you, I'd get someone with VAG-COM to clear the fault code. Go for a drive. See if the fault returns. If it does, then I'd be inclined to believe the system. I'd then just buy a new N249.

Be careful though, some parts places confuse the N249 with the actual DV, they think its one in the same, it isn't. Some parts places confuse the N249 with the N75 too.

Hope that helps.

AL
 
Cheers Al,

I've got the free download version of Vagcom, waiting for the cable I've ordered to arrive, so will try this when it turns up.

Thanks,
Jeff.
 
isn't the free version of VAG COM limited to performing certain checks though?
 
I have the same problem although the VAGCOM says the N249 vlave is open. I changed the DV and must say the car is much better but I thought if it still shows this problem then I might as well change that too. The problem is I need to find the thing and I have no idea what it looks like or where it is..any pics or help much appreciated.

Matt
 
Thanks for that, you did mention earlier that the valve sits on top of the engine on S3's, am i right in this and should I be able to find it. Another one, do you know the code for the valve to order it or is it just known as a N249.

Sorry for all the questions.

Thanks
Matt
 
Matt,

Sorry, didn't realise you had an S3. (Do yourself a signature mate! /ubbthreads/images/graemlins/smile.gif )

On the S3, take of the engine cover. See all that mass of pipe work and stuff covering coil packs 3 & 4? Near the front of all that, is the N249 with an electrical connector going to it. (I will try to post a pic/pdf later for you)

The part number I have, for my BAM engine, is:-

078 906 283 A

Martyn at VAGPARTS has quoted me £32.17+vat for this item.

I was looking at possibly replacing mine, but car seems to be running ok this week! /ubbthreads/images/graemlins/smile.gif

AL
 
Sorry AL,

Thanks for the great info, I must admit that my car is running better than ever with the new DV, it now has a new lease of life above 3.5K but since the VAGCOM is showing this fault I think I might as well change it anyway. It reports an open circuit so I assume it isn't controlling the DV as in open/close?

Sig done as well...not very good at this /ubbthreads/images/graemlins/ok.gif

Thanks again for the help.

Matt
 
ooooooh, Dolpin Grey with Silver Mirrors. Love that combination. Good choice mate.

I'm a bit worried about that open circuit warning. Yes it could mean that the N249 is faulty, but it could also mean that there is a wiring problem going to the connector that clip onto the N249.

The pdf is to follow.

AL
 
Many thanks Al, Lets hope it's not electrical!!
I shall attempt to test it this weekend.

Thanks again.
Matt
 
[ QUOTE ]
Jeff,

Its probably best to test the DV first.

A simple test is to:-
1) remove the DV.
2) Push the diaphragm within the DV up using a screwdriver.
3) When the diaphragm is up, cover the vacuum nipple on top of the DV with your finger. Does the diaphragm stay up, or does it come back down? If it holds in position, the DV is probably ok.

There is more accurate testing that can be performed, but you need a vacuum pump for this.

With regards to the N249. I think you are actually lucky that a fault code has been reported. A lot people, like myself, have various niggling performance problems with no fault codes reported at all.

Do you have VAG-COM? Or does a mate? What you can do with this is briefly test the actuation of the N249 by peforming what VAG-COM calls output tests, and what Audi call "Final Control Diagnosis". This sequence of tests basically actuates all the solenoid type valves on the car, e.g. activated charcoal filter, N75, N249, injectors and others. So what you could do is skip to the N249 test, and listen if the valve is clicking or not.

The official test is to locate the N249, disconnect all vacuum pipes from it, but leave the electrical connector connected. Attach a test piece of hose, start the final control diagnosis on the N249, and blow down the hose. You should feel air coming out, then not coming out, of the unconnected hose nipples, as the valve opens and closes.

After that its, testing voltage supply to the N249 and then wiring loom checks.

If I were you, I'd get someone with VAG-COM to clear the fault code. Go for a drive. See if the fault returns. If it does, then I'd be inclined to believe the system. I'd then just buy a new N249.

Be careful though, some parts places confuse the N249 with the actual DV, they think its one in the same, it isn't. Some parts places confuse the N249 with the N75 too.

Hope that helps.

AL

[/ QUOTE ]

Al, I've got the free download version of Vag-com not sure if this is suitable to test the N249 valve, do you know if it is and if so how I perform the test using VAG-COM, any help would be great, Jeff.
 
Just replaced the DV, so hopefully this will cure my problems I'll let you know what the outcome is.

Jeff.
 
Car is much quicker since I've replaced the DV, still hasn't cured the cold running problem though, and I've just read out the following fault code using Vag-com:- 17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 35-00 - -
Anyone got any ideas ??

Jeff.
 
If you havent cleared that fault after changing your DV, it could be an old fault.

Clear and see if it comes back.

If you did clear it, and its come back....

check the pipe work to and from DV


Especially check the N249 valve is plugged in and the pipes are ok it controls the DV, it will be on the end of the vac line (smallest pipe on dv)

on the s3 its on top of the engine under the engine cover. Not sure about the A3.

other than that its inspect all turbo /throttle hoses for being loose, splits etc.
 
[ QUOTE ]
If you havent cleared that fault after changing your DV, it could be an old fault.

Clear and see if it comes back.

If you did clear it, and its come back....

check the pipe work to and from DV


Especially check the N249 valve is plugged in and the pipes are ok it controls the DV, it will be on the end of the vac line (smallest pipe on dv)

on the s3 its on top of the engine under the engine cover. Not sure about the A3.

other than that its inspect all turbo /throttle hoses for being loose, splits etc.

[/ QUOTE ]

Hi Paul, I cleared the fault code, so it's re-appeared since, I kept getting the "N249 mechanical malfunction fault" so I replaced the DV, I'll check the pipe-work, could it be a throttle body problem ??

Regards, Jeff.
 
more likely to be a split or hose somewhere i would think.

Could even be a punctured IC
 
Are any of the hoses more common than others for splitting/leaking, do I need to check the vacum hoses or just the boost ones ? also where abouts is the IC located on a 1.8T ?
Regards, Jeff.
 
IC aka intercooler is in the drivers side between bumper and wheel arch.

It really could be any hose.

I cant point out specifics, as the hoses that are likely on the S3, are totally different to the A3.

Inlet manifold is round the other way etc. 2 totally different set ups.


for example...


an a3 1.8T would be similar to this...

41.jpg



and an S3 similar to this..

35.jpg
 
Just removed and cleaned the throttle-body and this seems to have cured the problem, I've only used the car a day since, but it drives much smoother and the fault code hasn't re-appeared yet
 
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