98.5 1.8t quattro -Canks but won't start! Help
 

Recent historic of the car since I bought it a month ago:

-oil changed to synthetics
-Lower left arm replaced
-4 coil packs replaced with new
-4 spark plugs replaced with new (erroneously gapped at 28 but should not be a big deal)
-Fuel filter replaced
-Stab links replaced with new

At this point the car ran great for 2000km, after which it suddenly stalled at a light. It would start again, and stall again. It became more and more difficult to start again and has now been in the driveway unable to start for 2 weeks.

I proudly purchased a VCDS License with HEX-USB+CAN Interface, which at first gave me some throttle codes:

5 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
16521 - Oxygen (Lambda) Sensor B1 S2: Signal too Low
P0137 - 35-00 - -
17967 - Throttle Body (J338): Fault in basic settings
P1559 - 35-00 - -
18048 - Internal Control Module: EEPROM Error
P1640 - 35-00 - -
17953 - Throttle Valve Controller: Malfunction
P1545 - 35-00 - -
Readiness: 0110 0101
Cleared codes.

-Throttle body was cleaned, and seemed to be in good condition.
-ICM was tested and resistance was all over the place on all 4 pins, so I was hoping this was the problem. I replaced it with a HUCO that came from a 98 passat in a garage. Can't remember what the Mohms were but I know that its at least the same on all 4 pins. Did not change a thing. The engine cranks but no spark.

4 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
17967 - Throttle Body (J338): Fault in basic settings
P1559 - 35-00 - -
18048 - Internal Control Module: EEPROM Error
P1640 - 35-00 - -
17953 - Throttle Valve Controller: Malfunction
P1545 - 35-00 - -
Readiness: 0110 0101
Cleared codes.

-Crankshaft Position Sensor was changed to a new one. No change.
-It was suggested that ECU might be bad. Once removed, there were traces of Verdigris on a few of the pins. I tried to clean them and reconnect. No change. At this point I was hoping the ECU was fried...
-Ordered same ECU that came from used but working A4.

Replacement ECU makes no difference, except that new codes have appeared (which I have cleared):
4 Faults Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
16716 - Knock Sensor 2 (G66): Signal too Low
P0332 - 35-10 - - - Intermittent
18014 - Rough Road/Engine Torque Signal from ABS: Electrical Malfunction
P1606 - 35-10 - - - Intermittent
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-10 - - - Intermittent
Readiness: 0110 0101

Other factor to consider:
-Fuel Pump Relay is clicking a lot when trying to start. I haven't replaced it yet.
-When ECU was replaced, I took the old one out and the new one in. No reprogramming or anything.
-Previous owner rebuilt transmission.
-ABS module was changed but never reprogrammed with the VAG-com. The code should probably be ignored.

I don't know where to go from here and would appreciate any help. I need the car back on the road.

problem solved
 

Code 18010 or P1602 means you unplugged the battery. Or your ecm/ecu is loosing power. I think you should buy an ecm/ecu. When your car stalls and your driving ,and you get that code thats it. Ecm/ecu.. Done

New ecm/ecu
 

Make sure you erase all dtc codes before starting.

I would expect the problem is related to a bad electrical connection somewhere. Check resistance from the battery post to the car body, and the positive cable connections at the battery. I wouldn't be surprised if your ECU doesn't have a clean 12V and proper ground.

Your clicking fuel pump relay doesn't need to be replaced, in my opinion, but it's a clue. How's your ignition switch? These are known to go bad. If the relay is clicking, most likely you don't have any fuel pressure.

UPDATE
 

With the help of ether, the engine started (hallelujah). Once started it runs fine (I did not drive it, just at idle). I turned it off and on again. It did start, but with difficulty, and the following code appeared: 17956 - Boost Pressure Regulation Valve N75

Cleared the code, it did not reappear. Now the car doesn`t start again -although I`m sure it would with ether.

Any reading I should check from the VAG measuring values? Any suggestions?

It sounds like the fuel pump is barely running because the clicking relay gives intermittant power to the pump. Try taking the cover off the fuel pump relay, and manually closing the relay contacts. The engine may run OK (don't try to drive like this). Also measure voltage at these contacts while the pump is running, which should be similar to battery voltage. While you are at it, clean the contacts using a white paper buisness card wetted with isopropyl alcohol.

stalling
 

Also keep in mind if it's your ecu i could be throwing all kinds of fake codes

Have you done a throttle body adaptation with VAG-COM? I have found that some A4 1.8l turbos with engine code AEB are starting sensitive to throttle body adaptation.

Maybe fuel filters backwards,idk if that would block fuel flow. Idk

FUEL PUMP is not getting power
 

Finally the problem has been isolated. Voltage at the fusebox is 0.215 and same at the pump. Connecting the battery directly in fuse 28 (fuel pump) will start the car. So the problem is between the battery and the fusebox.

The question is what to check now. I don't know how to follow the wire or where to look. I'm starting to lack time for all this and I think it would be cheap to get it fixed at a mechanic given the problem is identified, but if it's something I can do on my own quickly I'm all ears.

Thanks again.