My 1.8T was vibrating quite a bit at idle for the longest time. I can't even remember if it did it over a year ago though. But I just figured it was normal and didn't think much of it. But one day I was under the hood with a mechanic buddy diagnosing a noise and after pulling the coil connectors to check for a missfire we found #1 missfiring. But the weird thing was it got a LOT worse after doing that. It was knocking like crazy, CEL flashing, all the signs of a complete missfire. Turns out the #3 wire in the connector (this is the one from the ECU to the coil to tell it to fire) was broken off. It was already messed up but when we were unplugging it we must have completely broken it. Once that wire was soldered back in place there was no vibration at all at idle.

So I would do a thorough check for a missfire. It could be something very hard to diagnose like mine or it could just be a spark plug. The only way to really diagnose a problem like mine is to get a multimeter on the wires. The shop I took it to checked for continuity from the ECU to the coil and found the break. I tried to do it myself with a scope (expensive multimeter with fancy graphs and stuff) but I didn't have a probe that would fit into the connector on the ECU.

 

Hi everyone. Those of you that had this problem were you able to solve it? I have taken this car to a couple of people with the following tests and results. All the mechanics agree that the car is not supposed to do this. This is what was done so far:
-No faults
-Checked pullies (good)
-Checked timing of cams and crank (good)
-Checked Cam timing (good)
-Checked measuring block 90 (good)
-Replaced Spark Plugs
-Removed Exhaust (vibration still there)
-Replaced the driveshaft (internal cv damage),
-Checked subframe torque (good),
-Inspected Trans Mounts (good),
-Inspected Engine Mounts (good),
-Checked Harmonic Balancer (good).
-Cleaned Throttle body and intake manifold.

Do you guys or gals know of any performance enhancements that would cause a vibration? I still have the stock Snub Mount so that should be good. I read someplace that an aftermarket snub mount could cause vibration. Something in these cars wears down over time and causes this vibrationbut what is it? Idle Control Valve? Any suggestions as to where to go next?

 

try cleaning the MAF sensor