[s-cars] no-start...update

[Paul Gailus]

The ~20 degree shift you mentioned may be a non-issue, but it brings up the possibility that the crank sprocket could be shifting due to a sheared key. Apparently this has happened to a few listers. The following link describes this on an S2 that has the hall sensor inside a distributor:
http://www.picotech.com/auto/audi.html

You might check if you can get the cam, crank, and the flywheel TDC mark (if it has one) to align as described in Fred Munro's writeup:
http://s-cars.org/postnuke/downloads/pdf/Audi%20UrS4%20AAN%20Timing%20Belt%20R&R.pdf
or http://tinyurl.com/da8c3

If you can't find a flywheel mark, and also don't have an oscilloscope to try the procedures from Picotech, I believe the following approach could help. It assumes that you can observe the flywheel timing pin through the access hole for the reference sensor after the sensor is pulled (use a mirror if necessary).

1. remove the reference sensor
2. rotate the engine until the flywheel pin is observed
3. probe the output of the cam position sensor with a voltmeter in DC mode. The CPS should remain connected to the harness, unless you are supplying power and ground eternally to the proper leads. You should be able to get a probe onto the output signal at the back of the connector. I believe the wire for the CPS output signal is green.
The output signal should be low (less than 0.5 volts) when the flywheel pin is centered within the hole. As the engine is rotated sufficiently in either direction from this position, the output signal should go high to about 5 volts. If the required rotation angle is not reasonably symmetric as the pin moves either way from the access hole, there could be a sheared key. And if the results change when you apply some torque either way on the cam pulley bolt, that's even more evidence of a key problem.


-----Original Message-----
>From: theringmeister at triad.rr.com
>Sent: Jan 18, 2008 3:24 PM
>To: s-car-list at audifans.com
>Subject: [s-cars] no-start...update
>
>got home today and fiddled with the wires to the CPS behind the cover behind the sprocket, but without removing the sprocket as I didn't have anything to brace the thing with to keep it from turning.  When I attempted to remove it the whole thing turned about 20 degrees (with the belt intact and not skipping teeth, as it was zip-tied in place) I put the serpentine belt tensioner and tb cover back on and removed the zip ties, and voila! it started right up.  My guess is either I re-established contact in the wires to the CPS, or by moving the engine I somehow managed to get it started (not likely, but those are the only things that have changed since it wouldn't start).  I pulled codes and the only code I'm getting is for the Throttle position sensor (2212), but I'm getting it twice....not sure why.
>
>Could that cause a no-start condition?  I did unplug it once in my attempts to get the car started and have held the throttle to the floor on numerous occasions trying to get it started as well....
>
>Either way, I REALLY want the car back! 
>
>--
>Wylie Bean
>TheRingmeister at triad.rr.com
>90 cq
>91 90q20v sport
>92 UrS4
>01 allroad
>
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