Ugh....an electrical issue, I’m stumped

[Crownone]

BDF0E892-6877-4B15-B1AD-ED971C40FE97.jpegE5CEF4A9-59E7-477F-BF12-3FF40089FC5D.jpeg3FB54F82-9B54-4515-AB95-8866F7751ABD.jpg

Car: 2006 A4 2.0t 6spd Manual
Mods: Unitronic stage 2 tune
Test pipe
Stock air box mod, drop in kn filter
Inlet turbo hose silicone
S4 front and rear brakes
Recaro front and rear seats

Replaced parts:
Camshaft position sensor g80
Newer but used n205 valve
New n75 valve
New coolant fan module
Oem coil pack
Oem spark plugs
Oem pcv valve
Oem cam tensioner
Three rings for the cam adjuster

Issue: Car had intermittent boost surge at high rpm, then started having rough idle, but still built boost and ran smooth except at idle.So I pulled codes, misfire on 1 3 4 cylinders. Replaced spark plugs and coils OEM. Gapped plugs at .028.
Car ran better but still had codes. I scoped the intake valves and saw carbon build up, I assumed that was the issue. Rechecked codes and got the same misfire codes plus p0340, camshaft position code circuit high. Read freeze frame data and at idle timing was at -4.5 degrees. The cam tensioner was making noise so I pulled off the cam chain cover and found the old tensioner stuck closed. Set timing and checked it. Thought for sure this was my issue.

First start up still ran rough. Took it for a drive and the car started to run better and then bam, car ran like there was never an issue, built boost, pulled all the way till redline. Then out of the blue this same rough idle appeared. The same codes appeared. I checked power to the cam sensor and it read, 4.7v, 4.7v, 0v. This was at the three pins in the connector. At this point I figured I wasnt getting power to the cam sensor. I checked the relays under the ecu, which had water, but they were still clicking, I even took them apart and cleaned them.

After all the movement with the ecu, when I check the voltage back at the cam sensor, it read 5v all across the three terminals. So I figured I had an electrical problem. I located all of the grounds I could find, cleaned them up. Started the car, checked the battery 13.6v, the voltage at the alternator, which was 14.6 and all the fuses and relays in the ecu box and dash, all are good.

I replaced the the relays in the ecu box with oem ones. This is when the epc light popped on and the rest of the codes appeared, now I’m stuck in limp Mode and it seems like I have no choice but to remove the entire engine harness and search for breaks in wires. I was wondering does anybody know what section of the harness controls these components listed in the attached dtc printout? Or is it just my ecu acting up. The sensors that are listed have no power running to them.

P.s car starts right up, runs smooth and coolant fans are constantly on. Still in limp mode

[FatMongo]

I've heard continuously running fans are a sign that the ECU is having massive issues. How long have you had the car and are you certain the correct ECU is in the car now?

[canadianA4B7]

Bricked ECU if fans on all the time. This needs a Reflash on ECU to fix. If your tuned you’ll need tuner to get you your factory file flashed back then they should be able to flash over the factory file with their tuned file. Cud be wrong ECU, could be a flood car, could be a tuner file flashed over the wrong ECU file.

[SlvrArrw]

If there are electrical problems, won't hurt(cheap) to improve grounding to engine harness. Add additional ground wires to engine block not just to body panel.

Sent from my Pixel 3a XL using Tapatalk

[Crownone]

I will try that, I actually brought the car 1 year ago completely stock with a blown motor, had a donor car with an engine and swapped everything over. I had the runner flap issue so I had it tuned.

[Crownone]

Ok so I found out I had the ground wires behind the cam chain cover on wrong. I re adjusted it by putting the bolt through the middle, it is mounted on the cam chain cover, is that the correct place? Im still getting the codes. I am wondering if I just need a new wire harness

[SlvrArrw]

You could change harness, that's one option.
Step away for a while and think about it.
Maybe just confirm continuity from grounds and sensors back to ECU.


Sent from my Pixel 3a XL using Tapatalk

[Crownone]

Hey guys, I managed to get the car running like nothing ever happened, I’m just worried there is something going on with my ecu. I checked continuity throughout the entire engine harness from sensor to battery and I didn’t find any open circuits. Maybe I was doing it wrong because after looking at the ED for the ecu pin out, I found that the sensors in question shared a common ground, pin #14 from the ecu. I did some searching and I found this thread https://www.audizine.com/forum/showt...el-rail-sensor.
I had the same codes so I grounded the brown/black wire from pin #14 and the car is running great again. I had to unclogged the drain under the battery and clean and reseal the ecu box. I had about 6 inches of water in there. The ecu might be water damaged. It’s weird because this problem gradually happened over time. All the parts I’ve changed didn’t stop the progression.

[Crownone]

Found out the issue was actually the voltage regulator. I unplugged the voltage regulator, took off that extra ground I put on pin #14, cleared the code, it never returned. Looks like I am going to replace the voltage regulator