# 2005 Passat 1.8 Rough Idle / Misfire Please Help



## Tsabadlk (Nov 21, 2011)

I have a 2005 VW passat with 160,000 miles on it. If I start the car it idles great for about 1min but I hear a suction noise coming from the passanger side of the car somewere near the turbo and air filter. After the 1min idle the sound stops then the engine starts to idle very poorly and misfires and the check engine light flashes. If I give the car gass then the check engine light stops fasing and the engine runs a lot better but still not quite right. What I have done so far from reading other threads:

Replaced all four coil packs (Which Ive done a few times before)
Replaced the sparks plugs (with NGK double platnium plugs)
Replaced the purge valve (on top of the air filter)
Replaced coolant temp sensor (on the backside of the engine near the firewall)
Replace the crankcase vent valve (on top of the engine near the firewall)
Replave the crankcase breather hose (on top of the oil cooler under the intake)
Cleaned the throttle body.
Cleaned the MAF sensor.
Took off the intake and clean it. (It had a thin film of oil inside it)
Inspected every PVC hose and componants.
Checked all the check valves.
Took of the Fuel rail and cleaned the fuel injectors and replaced the O-Rings

The crankcase vent valve was leaking and the crankcase breather hose was broken in two pieces. I thought for sure that the busted crankcase breather hose would have fix it but it didnt. 

I ran the OBD-II codes.
Here are the codes before I replaced the parts listed above.

P0171
P0300
P0301
P0302
P0303
P0304
P0444

After I replaced the parts I now have the codes below:

P0300
P0301
P0302
P0304

I changed the new coil pack around, erased the codes, drove it about 5 miles and got the same codes.

I unplugged upstream O2 sensor and the car ran exactly the same. Im wondering if it may we the problem as it has 160,000 miles on it.

I am curious if my problem is a faulty catalitic converter, O2 Sensor, or wiring harness for the coil packs. Any advice on how to check these parts as they are all $$$. If you have another idea of what I should check that would be great too.


Thanks in advance.


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## Tsabadlk (Nov 21, 2011)

Over 50 people have looked at this thread and not 1 reply. Some please give me an opinion. I really need to get this crappy passat running again for my wife.


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## AmIdYfReAk (Nov 8, 2006)

http://wiki.ross-tech.com/wiki/index.php/Category:Fault_Codes

Look up the codes for What to test/check


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## Tsabadlk (Nov 21, 2011)

Thanks Ill give that a try. A friend of mine has a Jetta that had real bad throttle responce and he got the random cylinder pisfire code 0p300. He took his Jetta to VW as it was under warranty and they change the alternator and it fixed the problem. He said that since my passat was "drive by wire" that I should check the alternator and see if that may be the problem. Im going to check it today and see if it is pushing out 90amps as it should be. Ill will post back the results for everyone else to see as well.


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## Tsabadlk (Nov 21, 2011)

The Alternaor check out good. Does anyone else have any ideas?


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## Tsabadlk (Nov 21, 2011)

So I took the car to a VW dealer and let them spend 2 hours on it. They thought it may be a check valve so I let them replace it and it did not fix the problem. They dont know what it is and want to spend 2 more hours on it. I told them that if a VW dealing cant figure out what is wrong with a VW in 2 hours then Im not going to give them more $$$ to keep trying. Please someone give me something to check on this thing.


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## ibboydb (Jan 7, 2012)

*CEL P0300 Random misfire*

My 2K Beetle 1.8T is experiencing this. Have read a lot and tested and checked swapped coil packs, replaced coil packs and plugs ohmed out the harness. one thing I can not locate and have read in several forms could cause this is the *FSU igntion control module*. Have read that this is incorporated in the coil packs, but I have a Part #(4D0 905 351) and my local store has it. My Haynes repair manual says nothing about this module . Does this exisit on this engine / car and where would it be located?????:banghead:


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## Tsabadlk (Nov 21, 2011)

I believe the FSU igntion control module is the same thing as a coil pack just a different name for it.


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## Tsabadlk (Nov 21, 2011)

If you pull your spark plugs are they black?


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## ibboydb (Jan 7, 2012)

I talked to a good VW tech today, He advised to unplug your Mass Air Flow Sensor w/ the car running, if it straightens out, replace your Mass Air Flow Sensor.


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## Tsabadlk (Nov 21, 2011)

Thanks for the tip. I tried that and the car ran the same..


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## zanzabar888 (Oct 14, 2009)

Timing ok?

Bad gas? 

leak in intake? 

clogged air filter? 

clogged fuel filter?

any frayed wires to the injectors or coil packs?

No codes for cps, tps, or other sensors so I guess we can rule those out. 

Dunno, I guess you should take a good hard look at your timing belt. When was it last changed?


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## Tsabadlk (Nov 21, 2011)

zanzabar888 said:


> Timing ok?
> 
> Bad gas?
> 
> ...


Gas is good I just filled it up again. 
I cleaned the intake.
Replaced the air filter and fuel filter.
Replaced all 4 coil packs.
Injector wires and coil wires look fine.

So that brings me to the timing belt. It was replaces at 105,000 miles but I pulled the timing belt cover and there is a lot of brown dust...?? Not sure why there is brown dust under the cover but the timing belt still looks really good. I have heard from one guy on the forum that his timing belt boke and he did a vlave job and put a new belt on then had simulat issues and he found out that one cam was 1 tooth off and when he corrected that it fixed his problem but I dont see how the timing could have slipped one tooth one its own with out the belt being replaced recently.


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## Tsabadlk (Nov 21, 2011)

Also its wierd that the car runs great for 1 min on a cold start. Then after 1 min it starts misfiring..... There has to be something that changes after 1 min of the engine being started cold but I dont know what it is. I thought it may be the temprature sensor so I replaced that but no change. 

Any opinions on if a knock senor could be to blame. If so where it it located and how do you check it?


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## Slimjimmn (Apr 8, 2006)

there is a 90deg hose at the airbox (rubber) that goes from the hard plastic pipe to the rear side of the airbox that usually cracks. It has a crimp style clamp on the plastic line side and a screw clamp on the other side. In 04/05 the assembly line worker overtightened the screw clamp and slit the hose. common problem. check that hose


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## BISHILVR (Nov 17, 2011)

It sounds to me like it has to do with your sai system, possibly a stuck/leaking combi valve!


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## dcmike719 (Dec 29, 2011)

this happend to my audi i dont know if its the same but i di everything you did and it ended up being my ICM.


http://www.autopartswarehouse.com/s...54.html?intcmpid=Product+Listings+Best+Seller


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## Tsabadlk (Nov 21, 2011)

I will check that hose on the airbox. Does my car have an ICM? 2005 VW passat 1.8 turbo (B5). If so where is it located. Ive never seen it and Ive been all up in the engine bay. Also what is the SAI system? Is the SAI system the same as the PCV system?


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## BISHILVR (Nov 17, 2011)

SAI is the modern version of an egr system, on your car it involves an electric air pump, and an electronically controlled air valve on the rear of the cylinder head, the SAI system only operates on cold starts such as after sitting over night and operates for approx 60 seconds and then shuts off.


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## Slimjimmn (Apr 8, 2006)

05 does not have a ICM (on 97-00 1.8t engines on airbox)


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## BISHILVR (Nov 17, 2011)

Slimjimmn said:


> 05 does not have a ICM (on 97-00 1.8t engines on airbox)


2000 does not have ICM either, basically if it has the SAI system or drive by wire it doesnt have the seperate ICM.


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## Tsabadlk (Nov 21, 2011)

I pulled the Combi Valve. (Which sucked to do) I teseted it with a vacume pump and it is opening like it should. I checked the 90 degree hose at the airbox and its in good shape as well. Someone else told me that the camshaft position sensor may have gone bad so I pulled it and it looks ok but didnt know how to test it so I bought one on Ebay for $15. It should be here in a few days so I will put it on and let you know the results. Apparently the magnet in the sensor can become demagnitized and tell the ECU wrong information. We will see if thats my problem or not. 

I replaced the fuel filter a couple of weeks ago and it was stoped up a pretty good bit but it still did not fix the problem. Does anyone know if there is another inline filter somewhere that I could replace. My book didnt mention another one but I have read in the forums that there is anotherone but have not seen were it is located.


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## BISHILVR (Nov 17, 2011)

There is a filter/screen on the end of the fuel pump in the tank. Have you tried any dry gas or fuel additive yet? maybe you have water in your tank. I would like to see what happens if you unplug/remove the fuse for your sai pump (the fuse is in the ecu box outside). For that matter, does your sai pump work? do you hear it come on during the first start of the day when standing outside your car? it should sound like a small hand held vacuum cleaner motor/dremel tool running, but it usually will only come on if the surrounding air temperature is in the 40's.


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## Slimjimmn (Apr 8, 2006)

if you hear a sucking sound its a vacuum leak.

p0171 is system lean b1
p0300 random misfire
p0301 cyl 1 mis
p0302 cyl 2 mis
p0303 cyl 3 mis
p0304 cyl 4 mis
p0444 purge control 

looks like from those codes you have either a vacuum leak related to the evap purge valve (located on airbox, the 2 pin connector and has one vac line on each side of it. 

When the car is running spray some intake cleaner at the vacuum hoses by the airbox and around it and if the engine idle raises then the hose you sprayed is bad. If nothing happens I would assume the evap purge valve is bad. 

FYI a faulty cam sensor will cause a cam sensor code and you had no code for that. :thumbup:


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## The36Chambers (Aug 21, 2009)

*Vacuum Leak*

You've spent a ton of money in parts so far. Here's my guess:

This hissing sound you're hearing from the passenger side is your secondary air pump, which I don't think is a part of your problem, and is simply coincidental that the pump runs for the same duration at startup as the increased idle speed at start-up.

I think you have a vacuum leak, and the reason why the problem only appears after the 60 or so seconds is because this is the point where your cold-start high idle is reduced to the normal RPMs. When you drop the RPMs back down, you lower the pressure at the intake (from above atmospheric to vacuum) and your problem then becomes noticeable. 

You've made two statements yourself which point to a vacuum leak, the bit about the problem worsening after the 30 seconds (once the idle drops) and about the engine running better when you rev it (because you're pressurizing the intake and therefore masking the problem.)

Pull your oil cap and check for a massive amount of suction. Go along the intake and pinch each vacuum line, if the engine smooths out while you do this, you know that's where the issue is. You mentioned checking all the check valves, there are more than 20 something if I'm correct, high chance one of those could be bad and you could be pulling suction from somewhere you shouldn't. 

Give it a systematic troubleshooting approach, and think only about what goes on during the warm-up cycle. Please post once you've figured it out, I'm sure I'm not the only one who's curious....


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## Tsabadlk (Nov 21, 2011)

Great suggestion. Thats what Im looking for. I will do that tonight. Thanks! I have taken off the oil cap and there is a lot of suction there. That is a good thing, right?


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## jackedrabbit (Jan 11, 2011)

Sounds like a similar problem that I'm having. Could you please tell me what your ECU code ends in? Mine ends in DQ. me and my mechanic are both convinced its the ECU. Compare your checklist to mine and maybe you can find a solution. What are your rpm's at idle? Are they normal? Or low? 

Here's a link to my recent post: http://forums.vwvortex.com/showthread.php?5556714-B5.5-Passat-never-ending-misfire-(who-else)


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## Tsabadlk (Nov 21, 2011)

It idles low. Ill check the number on the ECU tonight.


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## The36Chambers (Aug 21, 2009)

*Check Valve*



Tsabadlk said:


> Great suggestion. Thats what Im looking for. I will do that tonight. Thanks! I have taken off the oil cap and there is a lot of suction there. That is a good thing, right?


Absolutely not. The vacuum should be barely noticeable, if even noticeable at all. I'm willing to bet your check valve between the crankcase breather hose that you replaced and the breather pipe running behind your block to the valve cover is bad. (because you shouldn't have a strong vacuum up there)

If you follow the hose to where it meets the intake manifold, pull the hose off, and stick your finger on there (the nipple on the manifold), see if the problem goes away and the idle jumps back to normal.

Please don't spend any more money on parts, ECU, etc. because I guarantee you're overlooking a simple vacuum leak.

I'm also disgusted at the fact that 600 people have read this post and only a handful have responded... Not everything has to be about crazy mods and tuning! :facepalm:


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## Tsabadlk (Nov 21, 2011)

First thank you for your help!! I tried pulling all 3 hoses from the intakemanifold and covering the nipple with my hand. Did you mean the hose on the back of the valve cover instead? I know you were talking about that too. Sorry I must have misunder stood you.


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## Slimjimmn (Apr 8, 2006)

intake cleaner or brake parts cleaner will find a vacuum leak in 2 seconds, no need to pull hoses. Just start the car and spray bursts here and there where the vacuum hoses are and if the idle goes up there is a vacuum leak at that hose. Under the intake there are a bunch of plastic "T" connections to vacuum hoses that break when they get to about 120k miles on the car. Very hard to find other then brake cleaner. :thumbup:


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## The36Chambers (Aug 21, 2009)

*Vacuum*

Slimjimm I agree, however if the problem is a faulty check valve, you'd be pulling vacuum from places normally under a very very slight vacuum, i.e.: crank case, valve cover, and unless you really sprayed in some tricky places you wouldn't necessarily find it. It's a vacuum leak but not really a vacuum leak, just excessive vacuum caused by a check/regulating valve not doing its job correctly. 

Having strong vacuum at the oil cap to me is just a tell-tale sign that it's the check valve to the crankcase breather assembly.

These cars are so damn tricky with all these check valves, and they're subject to hundreds of thousands of cycles in forced induction vehicles....


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## jackedrabbit (Jan 11, 2011)

In my opinion, and previous experience, I would get rid of the platinum plugs and run standard copper ones. I've had much better luck with those. You'll just need to replace them more often.


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## Tsabadlk (Nov 21, 2011)

Well Im in worse shape now then what I was in. I tried pulling the vacume hose off the intake manifold that runs down to the breather tube and covering the nipple on the intake and it didnt run any better but the car died after I took my hand off. I hooked the hose back up and now the car will not run at all. I pulled the spark plugs and the were wet with fuel but the engine is not fireing. Im wondering if I have spark or not. Anyone now how to test the plugs that connect to the coil packs with a volt meter


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## Slimjimmn (Apr 8, 2006)

did you just start the car from cold and run it for like 20 seconds then turn it off? if so you just flooded out the engine. 

The PCV valve is on the rubber "T" hose that that metal pipe coming from the back of the valve cover rubber hose. Its on the part of the T that faces the coolant resivour. Sometimes the PCV valves get coked with carbon buildup and the stick open or closed, most likely open in your case.


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## Tsabadlk (Nov 21, 2011)

Is there a way that I can test if that valve is stuck open without having to take it off. If Im thinking correctly I had to take the intake manifold off to get to that one last time.


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## Slimjimmn (Apr 8, 2006)

the valve is not too hard to replace 
Usually by removing the oil dipstick or oil cap when its running and getting a sucking sound or flutter sound means the pcv system is "clogged" or the pcv valve is stuck closed


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## Tsabadlk (Nov 21, 2011)

Is this the PCV valve that could be stuck open or stuck closed? 










If you can see the image its located here: 

http://www.autopartswarehouse.com/p...Rw==&title=T0VTIEdlbnVpbmUgUENWIFZhbHZl&text=


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## Slimjimmn (Apr 8, 2006)

yes thats the pcv valve on awm engines, awp its just the valve piece with no extra nipple.


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## Tsabadlk (Nov 21, 2011)

Ya mine s the AWM. I ordered the PCV valve a couple of days ago but it hasnt cam in yet.. I pulled off the old PCV vlave today and it doesnt seem like a valve at all. You can look through the straight part. Is there supose to be some type of valve in there that may have came out? This thing just looks like a 3 way vaccum connector except that it is round on one side. For now I put the old PCV vlave back in untill I get the new one. 

On another note the car still will not start. I remove the battery and let it charge all night. Put the battery back in and tried to start the car for about 5 seconds and it didnt hit a lick. I pulled all the spark plugs and they were all wet with fuel. I dried the spark plugs off with a rag and put them back in and tried to start the car and it fired this time like it wanted to start and then died again and wouldnt fire again. I pulled the plugs again and they were soaked with fuel. It seems like the car is getting too much fuel but I dont know why. Any suggestions would be great. 

I pulled the timming belt cover to make sure that it is in time and it is. I also tried drying the plugs again and tried to start the car with the MAF sensor unpluged but it did the same thing. Fired for a moment and then wouldnt fire again. What are the chances that I have a bad ECU?


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## Slimjimmn (Apr 8, 2006)

car is flooded out. 

1-pull out spark plugs 
2-clean them off with brake parts cleaner (the electrode part) and let dry 
3-unplug fuel injectors 
4- crank car over for like 10seconds 
5- plug injectors in and put spark plugs back in 
6- hold foot to floor and crank engine over, should fire up:thumbup: 


the PCV valve should have a plate and spring on the large round part.


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## Tsabadlk (Nov 21, 2011)

Thanks for such a quick reply!! Thats awesome. I will try it now and reportback.


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## Tsabadlk (Nov 21, 2011)

The PCV valve deffently doesnt have a spring and plate in it. So that may fix my problem as soon as I getting running again. My fingers are crossed.


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## Slimjimmn (Apr 8, 2006)

ya, if it doesnt have that, its either: 
1-in the valve cover 
2-oil pump pickup screen 
3-intake hoses somewhere 

lol:thumbdown:


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## Tsabadlk (Nov 21, 2011)

Yay the car runs again!!! woot woot. I tied what you said and that worked great. Taking the fuel injector wires loos and cranking it for 10 sec was the trick. Now hopefully when the PCV valve comes in it will work like a dream. 

About the spring and plate.... When I replaced the breather tube that was broken I took apart all of the PCV lines and cleaned them out as there was a lot of built up sludge in there. If I got lucky I may have flushed it out. I hope I did at least. I hope I never find out!! I will give another update once I replace the PCV vlave. Maybe it will be a good update.


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## Tsabadlk (Nov 21, 2011)

The new PCV valve came in. I installed it and the car runs better but still misfires. I opened the oil cap and now I have positive pressure there. I think only one cylinder is misfireing now but will have to conferm with a OBD2 tester later tonight. 

I hoping its just a coil pack because one of them did arc without a sparkplug in it when my son turned the key while I was removing the coil packs. Thats what kids are for though right...


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## Slimjimmn (Apr 8, 2006)

hope all goes well. :thumbup:


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## Tsabadlk (Nov 21, 2011)

Havnt got my frends cheap code scanner yet. I really need a VAGCOM. Anyone around Chattanooga TN have one that I could use. This is getting old fast.


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## Tsabadlk (Nov 21, 2011)

I had someone check it with a Vagcom and all it showed was misfire on all cylinders and it said to check the diverter valve. I replaced the diverter vale with one that is adjustble thats made from billet aluminum but it didnt help. The guy that scanned it with a Vagcom said that he was pretty sure it was a vacuum leak... The only problem is finding where it is.


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## dug2598 (Feb 29, 2012)

*Same issue*

I have the same issue on my 2004 Jetta 1.8t. I have changed the plugs, O2 sensor, Fuel filter and then found a vacuum leak in the upper Y hose replaced it but still get the same misfire codes and a very rough idle. I tried pulling the oil cap off while running and could not because of the amount of suction and when I pulled the dipstick out teh car died. I also chaecked again with carb cleaner and could not find a vacuum leak again. After reading all this here I believe I have a PCV problem but am confused as to what is what. I am new to the VW family and am not up to date ont eh termonology. As best I can tell there is not a real PCV on the car and it is just a bunch of check valves. I pulled the one under the intake manifold that is ina shape of a T that goes into the block held by a clip. I ordered one of these and hope this is it but I was able to blow through it though so I am now not sure about it. I have spent four weeks now on replacing parts and reading on the forum here and am so troubled by this car. I will say that the forum is awesome we bought this car at auction and did not know the issues when we purchased it but it would not change gears out of first and after finding the forum I was able to determine that it was the soleoids and replaced them from another post about that issue and it saved me $2000.00 Now I know this is something simple but DANG IT I cant find it. Any input will be most appreciated. Plus if the T I ordered works I will let you know


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## Slimjimmn (Apr 8, 2006)

a common issue on 1.8t passats/a4 is under the intake manifold on all the solenoids, there is plastic vacuum t's usually 3/8" that connects all the vacuum hoses for the solenoid valves. They crack and cause misfires at idle. When the car is revved its fine, but at idle it will be rough and misfire. 
You will hear a hissing sound if its a misfire. 
Also spraying the hoses with brake cleaner will find a vacuum leak.
The brake booster vacuum pump (suction pump) (large y looking plastic valve at the back of the intake manifold that has one end going to the brake booster and the other end going to the manifold and the 3rd part goes under the intake to the pcv valve) that valve either cracks or the valve inside breaks and causes a vacuum loss.
http://www.ebay.com/itm/1999-2005-V...ies&hash=item1e6ba1d440&vxp=mtr#ht_500wt_1282

just google it or search on here and there are plenty of pictures.

plenty of the vacuum valves like this fail:

















vacuum t fittings that look like this break:


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## dug2598 (Feb 29, 2012)

Thanks for the advice. I have ordered a T shaped plastic piece that is under the intake manifold that has several check valves in it I hope that is the cause id not I will try the Y shaped piece you had the link to.


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## dug2598 (Feb 29, 2012)

*update*

Wanted to let everyone know that I finally got my parts and put them on and FINALLY my problem is fixed after months of guessing and reading and trying everything I could think of I fixed. Let me recap. 2004 Jetta 1.8t that first started having a rough idle and getting misfire codes. Tried plugs, new O2 sensor, and fuel filter. That did nothing so kept reading and found that it sounded like a vacuum leak. Found one right on top on the upper Y hose replaced it and it got worse. Read somewhere to check the oil cap to see if it was stuck and sure enough it was. That led me to the PCV valve or the plastic T that acts as one, Someone also suggested the Suction pump so I ordered it figured it would be better to do them both at once while I was in there. Went out this morning and replaced the PCV and then pulled out the pump and there it was in pieces it had broken on two and the thing that really makes me mad is that whoever owned this before me had tried to glue it back together and had a hose clamp around it. Replaced it and wow what a difference runs better, brakes better, and I am able to pull the oil cap off now without prying it off with a screwdriver and it also runs with it off which it would not do before. So if anyone has this problem and I know there are a bunch. It might not be your fix but it is a good place to start. Bought both pieces off of Ebay and it was about $50 for both which for peace of mind is well worth it. Make sure you have plenty of hose clamps to replace the one time use ones and also have a variety of sizes. I also found it nice to have some extra hose available I had to cut one piece off and having that extra sure did come in handy, One last thing if anyone that reads this every meets the engineer that designed this vacuum system for the 1.8t engine please punch them right in the mouth for me PLEASE.


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## tbaeastcoast (Nov 9, 2008)

might be time to trade her in.


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## dug2598 (Feb 29, 2012)

Why? I fixed it. Plus I just got it......


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## maotsetung (Mar 30, 2009)

^ awesome find bruh! I have the same issue and been trying to figure out what's wrong. I'm going to check it out asap.


maotsetung


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## Tsabadlk (Nov 21, 2011)

I just took off my valve cover to see if my cams were in time and they were a little off. I started turning the engine over with a ratchet, and the cam chain tensioner moves up and down!! That doesn’t seem normal to a shade tree mechanic like me. I’m pretty sure this thing has variable valve timing so I didn’t know if that was normal or not. Thanks in advance. 

Mine does the same thing as this guy's: 

http://www.youtube.com/watch?v=VmFLzqPl4Ec


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## BISHILVR (Nov 17, 2011)

Yes, thats normal. Always make sure that your turning the engine in the direction of normal rotation though.


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