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zeroasylum
19-10-2015, 12:41 PM
MK4 gold 2001 1.6L AVU Enginecode

Hi all,

Car has not being running right and VCDS is registering a misfire on cylinders 2 and 3(not registering a code for it just seeing it in the measuring blocks). I was getting misfires on all 4 random ones but a full service and new coil pack ,plugs and leads fixed this. I am also not getting this error code

16726- Camshaft Position Sensor (G40): Signal too Low
P0342 - 35-10 - - -Intermittent


I am also randomly getting a puff of black (not blue) smoke every so often when I stop in traffic/at a light and then accelerate. I think this could be un-burnt fuel from the misfires but I am not sure.

Now before I change the sensor as it involves taking the cam gear off could someone tell me if my timing is right from these photos of the top mark and the mark in the little window down in the engine as I am concerned the belt may have jumped. (see links below for images)

29002>29001


Thanks

Crasher
19-10-2015, 04:01 PM
It could just be a faulty sensor but the AVU is an odd engine I don't see very often.

zeroasylum
19-10-2015, 09:34 PM
Thank you for the reply. You are correct it is an odd engine and annoying to get parts for. In terms of the timing marks in the photos. Are they correct. I have uploaded better photos I took this morning.

Thanks

zeroasylum

Crasher
20-10-2015, 03:48 PM
I suspected it would be an auto.

If the timing was out then you would tend to get code

16725 (P0341) Camshaft position sensor-G40. Implausible signal

rather than

16726 (P0342) Camshaft position sensor-G40. Signal too low

but in either case the protocol is to check the hall sender wiring and you could add you own test to that by using an oscilloscope to check for a signal and even better if it was dual trace so you could observe the G28 and the G40 against each other but VW don't provide any signal level information. You can check the valve timing in Measuring Blocks 12 display zones 3 and 4 as follows



The engine speed sender on the crankshaft transmits both an engine speed signal and a reference mark signal. The reference mark signal is generated by a gap in the sender wheel.
The Hall sender rotor ring on the camshaft has a 180°division so that for one half of each camshaft revolution it covers the window on the Hall sender and for the other half-revolution the window is exposed.
To synchronise the components when starting, the instant when the rotor moves into the magnetic window air gap (signal change from - to +) or when it leaves the air gap (signal change from + to -) is recorded.
When the reference mark signal on the crankshaft is detected, the engine control unit counts the number of teeth on the crankshaft mounted sender wheel. As soon as it has counted between 26...30 teeth after the gap, the signal sent by the Hall sender on the camshaft should change from - to + (rotor begins to move into air gap of the magnetic window). After between 86...90 teeth, with the camshaft already making its second revolution, the Hall sender signal should change from + to - (rotor begins to leave air gap of the magnetic window).
If the signal does not change within the tooth ranges specified above, this may mean that the toothed belt has slipped.


These are the timing marks


http://i222.photobucket.com/albums/dd20/Crasher1964/AVU%20timing%20marks_zps31dsatvn.jpg (http://s222.photobucket.com/user/Crasher1964/media/AVU%20timing%20marks_zps31dsatvn.jpg.html)