Volkswagen Passat Forum banner
1 - 17 of 17 Posts

· Registered
Joined
·
21 Posts
Discussion Starter · #1 ·
I have a manual 2000 Passat, engine code ATW, that started acting funny out of the blue (sort of). A bunch of youngins were driving on the road next to me and started revving their engine, so I revved back. Nothing prolonged, just a quick double rev... vruuummmm VRUUUUUUUUMMMMMMMMMMM. Something like that. Immediately afterwards, my car started running rough, not sputtering, just vibrating like something is off balance. If you put your hand on the shifter, you can feel the vibrations very well, but in general it feels fairly shaky just sitting in the car. I also have a little less power. The vibration stays no matter how fast you go, but tends to dampen a little when on the highway. The tricky thing is that there are no trouble codes being thrown. My thought is maybe a vacuum hose popped off during the revving, but I don't see any visible lines hanging. I took it to my mechanic, who is usually extremely good at troubleshooting, wasn't able to figure it out (didn't charge me either but I gave him something for his time). Any ideas what this could be?
 

· Registered
Joined
·
211 Posts
Not fully sure, I'm a newb with my Passat. But I know my previous vehicle would do that when the plugs were worn out. My quick guess, though I'm sure your mechanic checked for it, would be plugs, then the coil's.

I know these engines are an interference type, but could your t-belt have skipped just one tooth? Just thinking that there might possibly be a little room for a slight miss alignment of one tooth (as in one tooth won't interfere). Even one tooth will throw the timing out to even make a non-interference engine run pretty bla.
 

· Registered
Joined
·
1,044 Posts
I'll check. What would purple stains be from?
the motor mounts (they are dampeners as well).

check your snub mount too (that has no fluid, it's just a rubber round shoe).

did you mechanic put it on a lift? you can't know their condition by looking in the engine bay, you need to go under.

EDIT: I am only basing this on the vruum vruuuum. it could very well be a vac leak as John mentioned above.
 

· Registered
Joined
·
21 Posts
Discussion Starter · #9 ·
So my mechanic checked the following things:

- Timing belt was fine and aligned.
- Camshaft drive chain was fine and aligned.
- Replaced vacuum hoses... no result
- The PCV valve was bad. Replaced it but no results.
- Currently looking at check valves but don't see any bad ones yet.

The turbo isn't turning on. Not sure if that's related or an entirely different problem. Any suggestions?
 

· I had a steering knuckle in my shed. Really!
Joined
·
4,164 Posts
If your turbo isn't boosting (how do you know?) and you have a rough idle, it could be a leak in the charge piping, both letting in extra air under vac (idle) and allowing pressure to escape under boost.
 

· I had a steering knuckle in my shed. Really!
Joined
·
4,164 Posts
Get a vac/boost gauge and see what readings you are getting. You should get about 7 PSI at WOT, and about 20"Hg idle (a little less vac if it's an auto). Decelerating you shoudld be pulling 22-24"Hg.
 

· Registered
Joined
·
21 Posts
Discussion Starter · #14 ·
Alright, here are some updates...

My mechanic checked the following things: (I hope I got all this right)
- Check valves are ok
- Replaced the degrading vacuum hoses
- Checked fuel pressure (3.5 bar at idle, 4 bar w/ gas)
- Replaced the turbo bypass valve, now the boost is now working. It's showing 5psi but should be 7psi. Originally, it was 0psi, so 5 is much better.
- Now that the turbo is working, it's throwing a P1557 code (boost pressure regulator)
- Reset the throttle body

My car had other problems coming into the shop, so I'm not sure which ones are actually related to the vibrating.

Mechanic still needs to check the waste gate bypass regulator valve. My car is running much better now (has more power) but the vibrating still persists! Any ideas on what else it could be?
 

· Registered
Joined
·
21 Posts
Discussion Starter · #15 ·
PROBLEM FINALLY SOLVED! Over a year later, finally got it fixed. Turned out to be the problematic dual mass flywheel. I got it replaced with a single mass, as well as some cracked pipes in the breather system and the car runs smooth as butter. It has lots of power again, has no more vibrations, and gets a lot better gas mileage than before. I got the flywheel-clutch kit, since the clutch was ruined from the vibrating flywheel - plus you might as well replace the clutch while you're at it.
 

· Registered
Joined
·
2,022 Posts
Thanks for the update. I find 'problem solved' posts to be some of the most helpful (and reliable) posts so thanks for taking the time to update this. Enjoy the ride - these cars are so sweet when they're running right.
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top