My daughter's A6 suddenly would not run well enough to drive about 3 weeks ago after she came out of a store. It would start with nursing the gas pedal, but sounded like a tank. I could hear metal slapping inside the driver's side valve cover. After getting the car home, I removed the driver's side valve cover (Bank 2) and found that the nylon shoe from the top of the camshaft chain tensioner was missing and I could see one good size chunk of the shoe laying within. Error codes included P1392, which I assumed was a secondary effect. I also noticed that it looked like the camshaft was off one tooth (the intake cam was rotated one more tooth towards the exhaust cam than it should have been with the engine in the lock position).
I bought new nylon shoes and re-installed the tensioner and put the intake cam in the correct timing position. I expected it to all be good. I was severely disappointed. The car will only run with a lot of help from the gas pedal. The only error code it throws is P1392, although one time I did also got some misfires on cylinders 4, 5 and 6. The engine runs the same, even if I disconnect the bank 2 CMP. It also runs the same if I disconnect all 3 spark plus wires from the driver's side (4,5,6). I verified good spark on that side using plug #5.
I bought a new CMP (camshaft position sensor) and put it on, again expecting good things. Same results as before. I replaced the CMP with a used one (not known to be good). Same results. I replaced the chain tensioner with a used one (not known to be good). Same results. I replaced the ECU with a used one (not known to be good). Same results. I put the original ECU back and put the new CMP on again.
I then got a wiring diagram and have done several multi-meter readings. The results do not make sense me, so I repeated everything and wrote down exactly what I saw:
I disconnected the CMP connector for Bank 2. I measured the voltage across pins 1 and 3. It was 11.5 V.
With the CMP disconnected, I measured the DC voltage at pin 74 at the ECU and ground. I read 9 V with the ignition on but not running. To be sure I had the right pin, I shorted pins 2 and 3 at the CMP connector and the volts went to 0. Plus the wire color at the back of the ECU was the same as at the CMP.
With the CMP still disconnected, I cranked the engine and nursed it with the gas pedal. The CMP signal voltage first dropped down to a low value, then settled in around 12.5V After the engine stopped, the voltage only slowly came back down to about 8.8V. I don't understand how I got any voltage at all given that the CMP was not connected.
I connected the CMP and repeated this and got the same results.
I then tested the Bank 1 CMP at pin 44 on the ECU. It behaved differently. Sometimes the signal was about 8V with the ignition on and not running, and sometimes it was 0.05V. When I ran the engine, it settled in at about 9.3V. It also slowly drops voltage after the engine stops, except when it goes to 0V - then it drops immediately. I should note that the battery was getting weak and by the last test, it barely had enough to start the engine.

Any thoughts?

 

Update. I am no longer getting the P1392 error, but now I am getting misfire errors. I'm not certain, because I took the cams out and retimed everything, but I think the P1392 error was due to some oil inside the camshaft shutter wheel that might have been interfering with the sensor readings.
I started a new thread for the misfire problems.