[s-cars] No Start ABY/AAN engine - Problem Found?

[qshipq at aol.com]

Thank you!  And you then don't need these pics of the 3B flywheel I did up for you, maybe it will help others understand the concept...  
PP side:
http://forums.audiworld.com/picture.php?albumid=162452&pictureid=226928
Block side:
http://forums.audiworld.com/picture.php?albumid=162452&pictureid=226929

FYI, the wider pin block from the AAN is not available as a separate part AFAIK.  I purposely did not put 3mm pin dimension as Cody notes the 3B comes from the factory, as it's not a critical dimension.  It's critical in tooth-from-TDC placement, and in clearance to the sensor only.  I labeled it as "min" dimensions and in fact, you can go as wide as the AAN pin block on either an AAN or earlier (3B/MC flat or dished) FW.  IME, a wide pin top-shaved a bit longer than 11mm (= as long as it clears the block in a revolution) will give the strongest wave signal off the timing reference pin.  In a couple cases where I've had to 'redo' someone elses work, I have redrilled above the stock pin location, and just shimmed out the reference sensor for proper clearance.

HTH

Scott J

 

-----Original Message-----
From: Ben Swann <benswann at verizon.net>
To: qshipq at aol.com; cody at 5000tq.com
Cc: jc at j2c3.com; s-car-list at audifans.com; chris.miller at bqconsultants.com
Sent: Mon, Oct 4, 2010 9:50 am
Subject: RE: [s-cars] No Start ABY/AAN engine - Problem Found?


Well - son of a gun!
 
I just checked the two 3B flywheels that I had spare.  Neither of them have a pin protruding backside, but there is a nub where one should be.  I don't recall there being one on the one I installed, so this must be the problem.  Also, the flywheel I pulled off the AAN has no such pin.  but does have a large tab mounted where the pin would be on the 3B one.  There are also two tabs located like the pins clutch side on the AAN - that is where I confused them for the sensor pins.
 
So it appears there was no change in location of the pin with respect to the ECU programming, just that my pin is missing.
 
Now it all makes sense.  Wish I'd checked this before installing.  I am certain I can make this repair in situ.  The pin is easy to locate and I'm pretty good at drilling holes in tight spots even if it is hardened metal.  This is certainly a lot easier the removing the trans and I'd have to drill the hole anyway.
 
I had been under the impression that the two pins protruding from the front were the sensor pins - especially since the timing diagrams show two spikes that correspond to those pins.  However, the timing diagram is for Ur Quattro not the newer engines.
 
I'm wondering if I should install a tab similar to the AAN flywheel instead of a pin - it appears to be a centimeter square peice of steel that is located by two pins - one pin is where the pin would be and the other just below that.  I wonder if this is a dealer item.
 
Thanks Cody and Scott for catching this!
 
Ben