Yes i did use the search button to try and find a thread like it, some popped up, but were mostly for the 1.8T, and i have the 2.8 30V.

when my car is at an idle (stop light, warming up, waiting) sometimes, but not always, will the engine start going crazy. it jumps from low RPMs to about 1000 repeatedly. and then soon after that a pump comes on, which is right under the the cover of the air box, which makes a loud ticking noise, and when you grab it, you can feel it vibrating.

what could my problem be?
and i plan on seafoaming everything with my next oil change (about 600 miles)
it's just kind of annoying, and worries me slightly.
it got to the point where it completely died at idle, and normal operating temperature.

 

Sounds very similar to a problem I'm having. Mine isn't quite as bad but it will idle normally then go way down for about a second then be fine again. I also have a ticking noise but it's coming from around the coil pack (weird?).

Sorry I don't have an answer but I feel your pain lol.

 

Try a throttle sensor reset. Disconnect the battery for an hour or so (make sure you have your radio code, if applicable), then hook it back up. Turn the key on (don't start the engine), and listen at the back of the engine. You'll hear a high pitch whine. That's the TPS adjusting itself. Your idle will bounce and dip for a bit as the car relearns its operating parameters but you should start seeing an improvement. If that doesn't help, try replacing vacuum lines - the ones to and from the solenoid panel on top of the engine get very brittle and can break or crack. Replacing them with silicone lines should help your car run quite a bit better.

 

if it were me, I would disconnect the MAF in the airbox and see what happens I had a problem very similar to this and after chasing it around, I had to change the MAF. Been perfect since.

 

thanks for the help guys. i will try both of these, and i have to unhook the battery as well as i am wiring my car for subs. i wanted to do a seafoam treatment all around, so that would be a good time to replace vacuum lines, and hopefully its better than ever!

 

I'm having a little of the same issue, only it bounces down to 600rpm and right back up for a split second. I replaced a lot of my vacuum lines but im just gonna break and spend the 40 bucks on a smoke down test. Might be a good idea for ya to see where your leaks are

 

it died on me 4 times today while driving, while letting off the clutch and giving gas at the same time to take off, and once just taking a slow turn in second around 1100 rpms, and then boom died, which is problematic because in minnesota we just got a massive blizzard and i am counting on the quattro to get me places safely!

 

Interesting. I have a '98 2.8 30v. I took a look under my car after getting a p0411 and p0455 code and saw that my SAI pump did not have anything connected to it. The pipe that goes up to the engine was broken off, the pipe from the airbox was disconnected, and the plug was not plugged into it.

After getting everything put back together, now on a cold start it will idle around 1200, then drop for just a second to 1050 or so and back up. It will do this a decent number of times while warming up (about every 5 seconds or so). Before I reconnected everything, it would just idle around 1200 on a cold start, and then drop down to 800 once warm.

 

ahh yeah the sai pump is the little thing on top of the airbox correct?
because that is what is ticking while it does the whole odd idle thing

could that be my problem?


and another thing is, my car has burned a quart of oil in less than a week. 160k miles and in the past week i have only put about 150 miles on.

 

OP definitely has a vacuum leak.

SAI is not around the airbox; it's lower, near the passenger fog light.