That line leads to your diverter valve (DV). Did you check the entire length of it for cracks? It's possible it could be falling apart down near the DV where it's tough to get to from up top.

 

I rechecked it again today and I do need to get that replaced. I didn't find any cracks well any that i could see. The covering for the tub is def. falling apart and in several places the tubing is rubbing. I just took the neospeed snub back out and put a brand new factory one back in. Didn't see a huge difference with that but did help. I'm so disappointed though because I have no idea what to do now.

 

Funny I just picked up a 07 A2 2.0 qtro Conv and it vibrates at idle and when the car is coming down to idle. I have not brought the car back to the dealer yet.

Any updates?

John

 

yea i tried cleaning the mass air flow sensor today. Nothing changed. Actually the maf looked like it had just pulled it out of the box it was so clean. I was actually quite amazed. But anyway now thats it warmer the vibration at idle is better but when it dips below 60 it continues to get worse.

 

i'm kinda coming to the conclusion that the 1.8 and 2.0 are just rough running motors but i still have something thats not on par...does anyone know which check valves tend to go bad first?

 

I have a 3.0 and I have been chasing this effin problem for a month. I have finally sloved the other crap that was on top of it. I have replaced all of my Vac tube with OEM. I was getting a misfire from broken a tube-that's gone now. But get a lightly rough start up for 30seconds and vibration on idle. I am going to replace the check valves right now they have them at the auto store. TRY THIS sit in your car and gently increase the idle very little. If it improves then you could adapt your idle with a Vagcom. I tried that and it worked a little but I am pointed right at the vacuum system for this problem. Just happened to see your thread. If you want to test the check valves take it out and blow through it check valves only let air go one way then pressure test it lightly with a gauge to see if it leaks. I am going to do mine now with a seafoam. I'll take some photos of the checkvalve testing and put them up later. What a PITA this vibration is!

 

Well I only have one check valve and that's not it. It does let a little seep back through the wrong direction but nothing to write home about. I went to the store and they didn't have any left or I would have replaced it anyway.

If you don't have a pressure or vacuum pump tester just take the things out they are one way suck on them one way then flip it and you shouldn't be able to suck in any air then put your finger over the end and you should not feel suction on your finger tip. I pressure tested my system and there are no leaks from the manifold out. You need to do the same. Clamp off the manifold lines and pressurize the system with a pressure or vacuum gauge. If it does not hold pressure start clamping down the system until you isolate the leak.

I am doing a complete service on the car and so far it has reduced my vibration by 70% although I have left it for last because I knew it was a combination of things.

Replacing the vacuum lines and that did a little. $15
The new coils and plugs did some. $160,$50
I cleaned every electrical connection and applied di-electric grease. That did a little more. $4
Adapting the idle did a little more.(need a Vag-Com)
Changing the engine oil does a little at first.

MAF did nothing.
Air and Fuel filters did nothing- they needed to be replaced though.
Transmission service did nothing.
T-belt and snub mount that was not even there did nothing.
Tested the Fuel pressure -good
cleaned and tested the injectors -all good
replaced all of the Injector o-rings -did nothing
my engine has no oil leaks so there is no vacuum loss there

I think I'll go do the seafoam now and try adapting the idle again after that. I'll let you know. I am mostly after the roughness on start up now I think it may be linked to the Cam Adjusters because I can hear them clanking while it's rough. BTW it does not do it when it's warm.

 

if i can get you to put up pictures your my new hero. Thanks for your post. I've essentially done most of that list. My car's idle does get better if i touch the gas. Mine is also the roughest for 30 seconds and then is the worst in Drive and Reverse. I've replaced motor mounts, snub mount, changed transmission fluid, cleaning MAF (which was in perfect condition), spark plugs still only have 10000 miles on them, did ohm testing on each coil. Even bought a coil and slide and replaced each coil to see if I noticed a difference. I seafoamed my car which helped performance ALOT. I know its not fuel related because it would be surging (the rpm needle would bounce up and down). I did find a hose that needs replacing but its the one that runs to the diverter valve. I haven't done any other vaccumm testing and haven't messd with the check valves yet.
Also I've been wanting to test my check valves but do you just take them off. What about the clips (or fasteners) that hold them there?

 

Just take them off and remove the vac lines, remember which way they go.

To see if the one way part is working just literaly suck on it both ends. one way you can the other you can't. Mine is bleeding back slowly but with all of the vacuum in the system there is no way thats causing it. But you also need to pressurize it to see if it is leaking. Keep in mind My engine is a 3.0 not a turbo so you have more vacuum operated crap then me.

You are going to need some little needle nose vise grips and a cheap *** pressure pump to test your lines for leaks.
I like to use pressure because it is easier to locate leaks. If your lines are old and the mesh falls of in your hand you can order a 5 meter roll of oem from ecstuning.com. Once you start playing with it you will need some. In a pinch you can use whatever junk they have at the auto store usually winshield wiper line. Also grab some T's and rubber caps they get brittle too.

Start by locating where it comes out of the intake manifold and clamp that off. back track a little to the next fitting or cut it a little past there and install a T and that is where I would install the pump. Pressurize it a little, you don't need alot. It should hold pressure, needle should not move. If it does put a clamp down the line until it does hold pressure. Then move it down until you find the leak. I will say I hate to tell people to just replace parts but Vac tube is cheap. You will realize how old it is when you start playing with it.

This is my tester and the valve itself was leaking not the plastic casing. It shouldn't leak.


This is a photo of how I splice my pressure tester in. You do not need to clamp the lines like you hate them just enough to pinch them off.


Your gauge shouldn't move with pressure in it.


Do you have a Vag-Com and a Bentley manual for your car?
Don't worry about the fasteners and cable ties you can tie them back down with new ones later.

 

Thanks for the update... I took the car back yesterday and spoke with the service guy.. He tells me all 1.8 and 2.0 have this idle issue.

Well does anyone on here have a 1.8/2.0 that does not have a vibration?


John