First post, I have found a wealth of info here since purchasing a 2001 a4 Quattro 1.8t awm about 3 months ago. Looking for some insight. I have vag-com and a Bentley manual, which I have studied until my head spins.

I bought the car knowing it had a 16725 camshaft position sensor: implausible signal code.

Since replacing the cam chain tensioner and fixing a short in the plug for the Camshaft position sensor, the code is now

16727: Camshaft Sensor Signal too High

So in my extensive diagnosis, I have found that pin 2 on the CPS that goes to pin 89 of the ecu shows ~5 volts power, even with key and main power relay removed. I cut the wire within a few inches of the ecu (plan on replacing wires once issue is resolved), and confirmed that there is 5v on pin 89 of the ecu.

My limited understanding is that the pin 89 is a sensing wire, and therefor should not have ANY voltage. Is this correct? If so, what would cause there to be power on this wire? 5 volt power source leaking to ground somewhere? I can't really find info on if and where the sensing wires are finally grounded at to test for power leaking to a ground.

I have also found that the camshaft tensioner actuator ground trigger wire, (pin 2 on connector to pin 115 to ecu) has 5 Volts power on it as well, which I assume isn't normal.

I am running the car with both CPS and Actuator disconnected.

The car surges at idle, from 800 down to 750 and bounces back up to around 900, and continues rhytmicly. I have noticed when the driver window is closed and I hit the window up switch, it causes the idle to drop to around 700 rpm before surging up.

Logging the timing at idle, it shows around 6-8* BTDC, and when the rpm drops it jumps to around 17- 2X* BTDC. When the rpm comes back up it returns to 6-8* BTDC, again in rhythmic 1-2 second intervals with the idle speed surge.

I also have a N-110 shift lock solenoid short to ground code, which may or may not be related. I have pulled the plug off the N-110 solenoid, and it has 2.6 volts across the pins, which drops to 2.2 volts when I hit the brake pedal. I gues the small amount of voltage isn't enough to engage the lock, as I can shift into reverse and drive and park without hitting the brake pedal.

Any help would be greatly appreciated.
Thanks in advance,
Ryan

 

Just from reading your post I can tell you you know significantly more about electronics and more than likely cars than I, so take my advice with a grain of salt...

But I've had two sensors (one an O2 sensor, and one a coolant temp sensor) that were brand new and after put in, they gave me CEL's that were along the lines of "Signal too High". I had no idea what to do so I just bought new sensors each and they worked fine.

 

Thanks for the quick response! The previous owner put a new oem camshaft position sensor before I got it, and I even picked one up at the salvage yard to swap on, to no avail. I have also swapped 2 other sole pods onto my camshaft adjuster, which did nothing.

I believe it is a grounding or ECM issue since there is power on what should be the ground wire, sending a net voltage of around 7 volts to the actuator (12v on power - 5v on ground = 7v).

 

Well we've quickly surpassed my knowledge and therefor advice.

Good luck!