Jonny K

It was completely black and a little gummy on the intake side. When I was finished the screens were silver and shiny again and the inner components fairly clean. I soaked it in alcohol for a good hour and used Q-Tips to scrub everything I could. I wasn't able to fully get the brown marks off the tiny filament inside, something I wasn't about to touch. I'll post pictures later (no time now). I also opted to remove the outgoing screen after reading the forums.

So:

Samco hoses installed
N75 replaced
MAF cleaned

What's next?

quattro20v

did you replace the bypass valve?

Jonny K

No

quattro20v

Here is a list of things to look for from SJM:

Boost Problem Checklist

Here is a checklist you can go through when you have low or high boost problems.
LOW BOOST or Running poor issues
Check for any stored ECU fault codes, are the knock sensors working ok?
Read the Measurement block values using the VAG-COM, look for anything out of the range
Check basic engine timing, flywheel, camshaft and distributor rotor position
Check Throttle Cable Adjustment
Check Air Filter, is it really clogged up?
Check/Replace the Turbo Bypass Valve, check small vacuum/boost hose to this valve
Check Idle Stabilizer Hoses, and other small vacuum/boost hoses
Check basic fuel pressure and correct operation of the rising rate fuel pressure action by applying vacuum or boost to the vacuum/boost hose connection
Check fuel pressure regulator for leaking into the vacuum/boost hose fitting (rich running)
Check ECU moisture trap hoses (fuel filter lookin thang) behind black firewall cover (AAN S4/S6)
Check ECU Connector Terminals for corrosion, remove connector and use contact cleaner
Replace small vacuum hose from Bypass valve to Intake Manifold (3B engine)
Check the Operation of the Multi-Function Temp Sensor (1991 200Tq 20V Only)
Temporarily disconnect Multi-Function Temp Sensor 4 pin connector and recheck boost output (1991 200Tq 20V Only)
Remove and inspect the Intercooler exit hose (Ribbed Hose) and the lower turbo exit pressure hose for leaks.
Check the rubber hose between the intake pipe and the throttle body.
Check Vacuum hoses and their connections at the back of the intake manifold
Check/Replace the coolant thermostat, is the engine running too cold? or too hot?
Check Engine Coolant Temperature Sensor Resistance and connector wiring
Check the operation of the Waste Gate Solenoid using the ECU Output Test
Check Waste Gate Solenoid hoses
Check Air Temp sensor resistance at the ECU, and Repair the Air Temp Sensor wiring connections if needed.
Check Throttle Position Switch/Potentiometer for intermittent operation
Check Altitude Sensor Voltage Output and wiring between sensor and ECU
Plug or pinch off hose to lower waste gate and check for maximum boost and overboost cutout
Check Waste Gate for sticking open, defective spring?
Check the Exhaust System Back pressure, possible exhaust restriction
Inspect the Turbo inlet vanes and end play, has the turbo compressor nut left the building? or the turbo seized up, broken in half, or otherwise gone south?

Jonny K

The screen before a full cleaning (but after an initial wipe). It's all gummy and black, even though I had already wiped it (it was fully black before the wiping).

<img src="http://pictureposter.audiworld.com/111658/img_5002.jpg">


The inside, on the side the incoming air hits.

<img src="http://pictureposter.audiworld.com/111658/img_5009.jpg">

<img src="http://pictureposter.audiworld.com/111658/img_5011.jpg">


Partially cleaned:

<img src="http://pictureposter.audiworld.com/111658/img_5013.jpg">


After cleaning:

<img src="http://pictureposter.audiworld.com/111658/img_5017.jpg">

<img src="http://pictureposter.audiworld.com/111658/img_5020.jpg">


From the reverse side:

<img src="http://pictureposter.audiworld.com/111658/img_5022.jpg">


Re-assembled with the cleaned screen:

<img src="http://pictureposter.audiworld.com/111658/img_5023.jpg">

UrS4boy

Otherwise, I don't understand why there is so much grease build up on the hot-wire support tube and the fins of the heat sink.

Jonny K

Nope, paper. Changed regularily.