So here's the story. Drove my car to work Thursday morning, about a 30 mile trip, nearly all highway miles. As I approched my work place and stopped at an intersection the car bucked and started missing terribly as I crossed. I limped it to the parking lot and shut the car off. It should be noted that the CEL began flashing when this happened. I started the car back up and it seemed to be firing on all 4 cylinders but now has a loud tapping sound- seems to be coming from the top of the motor. So as not to risk it I had it towed to my frineds shop.

I stopped by there today and did a compression test, all cylinders are around 150psi. Then took the valve cover off and inspected the cam and chain. Everything looks good and tight. At this point I'm suspecting a collasped lifter, even though they all look like they are making strong contact with the cams. I put everything back together and cleared the codes. Starts and runs but still has a bad tapping sound. Going to try and link to a video on youtube.
http://www.youtube.com/watch?v=qW7U1H7mXHY

Anyone have any suggestions? Or if you want to come it get it for $1500 it's yours.

 

And it would appear that my oil pressure is good- light comes on before I start and goes off when it's running. Also looked like everything was wet with oil when I took the valve cover off

 

You were misfiring. Happens a lot on the 1.8T. Call a dealer near you and see if your car qualifies for the coil pack recall. Scan the ECU and see what cylinders were misfiring. If it's one or two it's likely coil packs or plugs. If all four it may be an ICM issue.

 

The problem isn't misfires now. I believe they were a result of something else. I've cleared the codes (random misfires, cylinder 1,2,4 misfire) and it runs and idles fine now, other than the loud tapping noise. ICM is new less than 12 months ago and one coil pack is new (#1 cylinder). My problem is mechanical, just trying to narrow down what mechanical part is causing the noise. With good compression I think I've eliminated a bent valve. I just don't know much more about the design of this head. After removing the valve cover (or cam cover as it may be) I see no rocker arms or springs like I would in an older conventional head design.

What are some typical mechanical failures of the 1.8T engine that would cause this loud tapping sound, but appear to run fine otherwise? From my experience I feel certain that it's in the head somewhere. In my mind I picture a failed spring, assuming that's what holds the valve closed- as it would in a non-overhead cam design.

Your thoughts are welcomed.

 

Some more info:
So I cleared the codes and decided to drive it home so that it wasn't going to be sitting at my friend's shop for a long time. On the way home it began sputtering and misfireing again, check engine light started flashing again, then stayed on solid. Engine smooted out about a minute later and drove home fine (aside from the CEL). Here's where the story turns.... as I pull into the driveway I noticed something- it wasn't tapping or knocking anymore. The engine now sounds perfectly fine. Weird

I took it for another spin and the car behaves as though nothing is wrong- it must have fixed itself!

Car still for sale at $1500 as is.