Hey, all. 2002 TT Roadster, 1.8T 225, 173k miles, 6MT. I've been slowly taking care of maintenance and other issues on this car and learning as I go. I'm pretty good at instructions, but no good at "what is that noise?". I was hoping someone could lend a hand.

The car doesn't get driven often, especially not in the winter, but I have the weirdest noise on acceleration, and it's hard to describe. Almost like something flapping against something else and making an almost grinding noise when it does it. It may coincide with a loss of power -- though I am positive I still have one or more vacuum leaks in my system, so who knows. I've narrowed it down to happening in either first or second gear, I don't really hear it -- or if I do, just barely -- in third and above, but it does seem to span the 2,500-6,000 rpm range in those lower gears. I haven't been able to isolate yet if it's even coming from the front or rear of the car, but my mind tells me it's from the rear... but it almost makes less sense back there.

I've attached an mp3 of an in-cabin recording of the sound. You can hear me start in first, and after the shift to third, it's down to 2-3 taps, and by fourth, it's gone. If anyone has any ideas, I'm all ears.

 

Engine light on?

 

Sure is! Here's where it stands now, though I am going to clear and re-try after some changes...

18010 - Power Supply Terminal 30
P1602 - 35-10 - Voltage too Low - Intermittent
17965 - Charge Pressure Control
P1557 - 35-00 - Positive Deviation
17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 35-00 -
16795 - Secondary Air Injection System
P0411 - 35-10 - Incorrect Flow Detected - Intermittent
17545 - Fuel Trim: Bank 1 (Add)
P1137 - 35-00 - System too Rich
16514 - Oxygen (Lambda) Sensor B1 S1
P0130 - 35-10 - Malfunction in Circuit - Intermittent
16519 - Oxygen (Lambda) Sensor B1 S1; Heating Circuit
P0135 - 35-10 - Malfunction - Intermittent