haginj

Hello! I recently bought a fixer-up-er A6 2.7 biturb-quattro, wich of course has some issues.
The main problem at the moment is hesitation during acceleration over 3000rpm with some smoke and a issue with reverse on my ZF 5hp19 automatic gearbox.

The issue with acceleration greatly improved today after replacing vacuum lines from wastegates in the front of the engine, that rid the Overboost code, but it still hesitates alot over 3000rpm ish.
My engine throws a CEL and the code: 16725 - Camshaft Position Sensor (g40): Implausible signal: (P0341)
What ive done today is check the wiring from the sensor, and i have replaced the sensor with one from another car. Before changing the sensor i got this code: 17746 Camshaft Position Sensor (G40) Open or Short to Plus: P1338.
I get the following voltage on the connector to the CPS: pin 1, 13,7v with car running. Pin 2, 5v with car running. Pin 3 is ground, and seems to be working.
Some of my main questions: Will the CPS error result in hesitation? Would the car run as smooth as silk at idle, and also when reving in neutral/park if the timing was off? Timing done by VW/Audi's certified workshop here, aprox 4000km ago.
I also get a fair amount of white / blueish smoke, im guessing the turbo on the left side, aka drivers side might be bad? Weird thing is i saw there was quite a lot of oil on the ground, also on the left side (drivers side). (Not in the UK btw, to clarify). Will inspect oil leak more thoroughly tomorrow.

Over to the gearbox and its issues:
I have recently flushed the gearbox with a filter change, and driveability in all forward gears greatly improved. I still have a big problem with reverse, the car goes into reverse quite hard, it slams into reverse "two times" with a few second delay everytime i try to reverse, after this i can reverse for about 3-4 seconds and then it seems to drop reverse, like the car is in neutral. I checked live data with vag com, and when putting it in reverse, it registers the shaft rpm to the same as the engine rpm, for about 3-4 seconds, then goes back to zero. NO DIFFERENCE IN THIS ISSUE WITH OR WITHOUT TCU CONNECTED!
Only errors i have gotten from gearbox is: 17090 - Transmission Range Sensor (F125): Implausible signal: P0706 and 18158 - Supply voltage too low: P1750. At one point earlier today i got: 18265 - Load Signal: Error message from ECU: P1857, but this didnt seem to return. (I disconected both ECU and TCU numerous times so this might be caused by that).
In regard to the supply voltage low, i also get this error on the ECU, the Insturment Panel and other control units. Im beginning to think there might be a bad ground or maybe a bad power relay somewhere?
Worth mentioning, the module under the driver seat, wich controls interior lights and central locking etc, is constantly clicking, and some of the lights (for example the red light on the door) is flickering to the same beat as the flickering relay in the control module. I also noticed the dashlights flickering at one point while test driving.

Weirdest part about the whole car, when i first got it to the garage i could not get my vagcom to connect to any control units, but after disconecting the secondary air pump wich constantly blew the fuse in the ECU box (40amp fuse) i suddenly could connect to both engine, abs, airbag, tcu etc.
After a lot of trial and error i cant seem to connect to ECU or TCU when key is turned to 2. stage, i can only connect randomly sometimes when car is running.
Vagcom seems to be able to connect to Instrument Panel whenever i try.
Can this be caused by the "Low voltage on terminal 30" error, wich i seem to get on most of the control units?

This became a really long post, so if you're still reading im really thankful! This car became more of a headache than i imagined.

If i ever find a solution to all of this, i can promise everyone on the interwebs that i will post all the solutions!

Thanks in advance for any assistance on this, i really want to experience this powerful engine with its full potential!

Regards from Norway!

georgeb944

16725/P0341/000833 - Ross-Tech Wiki

haginj

I have checked all the codes, i just cand find the correlating issue causing low voltage error, im starting to think that might cause a lot of problems.

georgeb944

I noticed that you only tested voltages on the offending (G40) cam position sensor. How does that compare with the other cam position sensor on the other bank?

haginj

Will try this, also worth mentioning is that when i disconect the rear cam sensor (other bank), i get the same error as a previously had on the G40 one (short to ground).

haginj

Short to plus, not ground. Sorry.

haginj

Small update, at the first start of the day, the car reverses perfectly, and i kept it in reverse for a good while. After changing to D and back to R it started acting just like yesterday, apart from only slamming into reverse 1 time, not 2 like yesterday. Same issue, after about 4-5 seconds it behaves like its in neutral.