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

[John Cody Forbes]

First off, you can not accurately place the pin in situ. The hole must be drilled using a milling machine. It is critical. 

Second, you do not want the pins on the cam. The timing belt has slop and the valve springs cause the cam to bounce back and forth in this slop. This will cause an ignition timing variance. Because it's on the cam that variance will be doubled. You do not want your ignition timing bouncing around +\- 10 degrees ;-).

I've got more input, but I have to get back on the road. I'll send another message at lunch time.

-Cody (mobile)

On Oct 2, 2010, at 12:21 AM, "Ben Swann" <benswann at verizon.net> wrote:

> Well I believe I have found the problem and it is not one of those where finding the problem is most of the battle.
>  
> I have suspected something up with signal  synchronization between the Hall and Flywheel Crank Reference and Crank Position  sensors, but everything seemed to be checking out electrically.   I borrowed a Vantage Probe in order to check the waveform on the sensors.  The hall is putting out a nice square wave right where it should.  What is difficult to see is the pulse on the flywheel sensors - very slight, although the ref sensor does trigger the fuel pump relay.  Yet the car won't start and fuel pump relay only trips on briefly as the engine turns over.
>  
> I manually probed for the flywheel pin - there is a convenient hole in the trans that shows the  first pin to coincide about dead middle of hall window.  At first I though - so this is not the problem, but then realized that the ref. sensor is mounted lower on the bellhousing - almost by 60 deg.   Bad thoughts that I might be missing a pin - no they were there.  But did not make sense that the first pin was basically going to be sensed about 60 degrees too late - after the hall window closes.  Basically you can think of the hall sensor as opening up a gate for the other signals to pass through.
>  
> So, here is the information that I did not give earlier because I did not think it relevant - I used the flywheel from a 3B engine from 200 quattro 20V.  Why?  Because earlier research indicated it was the correct thing to do and the dual mass spring loaded AAN flywheel parts are more  expensive and have possible durability issues.  I was for some reason under the impression that they were basically interchangeable.  Well they are, except for one thing - the flywheel pins are located differently.  In fact, the AAN flywheel does not really use pins, but has metal protrusions.  So, at first inspection things looked OK and I installed the 3B setup.  Now that I am looking and on closer inspection, the AAN "tabs" happen at just after TDC and about 60 degress later for the second tab.  Whereas the 3B pin #1 happens about 60 deg. after TDC and #2 60 deg. after that.
>  
> So, the logic of the AAN ECU must have been recoded for different pin location - all other things being similar on the engine crank, bellhousing, etc.  GOTCHA!
>  
> Now, I'm trying to figure out how I can make this work without pulling the transmission out.  I'm exploring some ideas and appreciate if anyone has a good way out of this predicament - maybe someone has dealt with this very issue and has a good solution that is easily implemented.
>  
> So far i've considered:
>  
> 1. pull trans and install AAN flywheel setup.  This is probably the most sure fix, but I already pulled the trans. out after installing due to an issue, and now it is even more difficult with everything completely hooked up - axles, wiring, exhaust.  I really don't want to do this again - I'm so close!
>  
> 2. install a pin in the flywheel in situ somehow.  I may be able to access through the starter hole, drill and insert pin  through.  Investigation reveals that I would not be able to do this without drilling through existing hardened pressure plate retention peg - located ironically just where the pin would have gone.  Still this is an option if I can locate the pin accurately.  I would probably need to yank the second pin that would now be pin #3 - I presume it would throw things off on startup.
>  
> 3.  a. Relocate the sensor.  This option I toyed with a little already.  There is that hole in the transmission I mentioned - it is right where one would expect the pin should be at TDC.   This is a feature in the 01E transmission installed.  I epoxied a spare ref. sender in the hole using a spare bracket.   However, I was not able to get a good read on the pin - maybe I just need to seat is in a bit farther.  That epoxy is holding better than I thought, so will need to be removed by force. 
>  
> I toyed with a few spare sensors using the scope.  The flying steel pin/tab needs to almost come directly in contact with the sensor.  If I brushed the sensor with a large steel screwdriver, I could get a spike, but waving the screwdriver about 1/16" away gets nothing.  A gap the size of a business card works OK.  This is a very close gap, and the sensor would be reading near the end of the pin.  I did verify that I could get a good read near the edge of a pin using a spare flywheel - showed good on scope and also trigger the fuel pump.
>  
> 3b.  What if I mount a pin (or two) on the cam sprocket and hang a sensor off the cover plate with a bracket?  Can I get away with 1 Pin?  Is the second pin required?  Also, since the cam only revolves once every crank rev. I might need another set of pins 180 deg. out.
>  
> Ideas.  Has anyone installed the 3B flywheel on AAN/ABY or other  - I was sure I read this, but apparently did not get the full picture.  I'll probably work with 3.a. tommorrow some more, but perhaps there is a better idea!  It would be so nice if there was a jumper inside the ECU that deals with this!
>  
> Ben
> 
> : 
>  [ Date: Mon, 27 Sep 2010 00:34:26 -0400
> 
> From: "Ben Swann" <benswann at verizon.net>
> 
> Subject: Investigation further[ Fusebox internals - map/diagram]
> 
> To: <audi at humanspeakers.com>,   "'John Cody Forbes'" <cody at 5000tq.com>
> 
> Cc: quattro at audifans.com, '200q20V mailing list' <200q20v at audifans.com>
> 
> Message-ID: 71CB33CEFB2B415885FA1BD1E285E993 at swansong
> 
>  
> 
> OK - I have been poring over wiring and connectivity to figure out why the engine does
> 
> not start and run.
> 
>  
> 
> Recap for those who are interested:
> 
>  
> 
> ABY "S2" engine installed with ABY wiring harness.  All connections for the harness are
> 
> to the fusebox per factory.  Ancilleries like instrument cluster - Tach, etc. are left
> 
> unconnected.
> 
>  
> 
> On Crank, the fuel pump does not run.  Checking obvious suspects starting with Hall
> 
> Voltage and operation - that is good and switching. 
> 
>  
> 
> Diagnostics attempted both by wiring for VAG-COM and simple LED test hookup do not work.
> 
> The LED lights when switch on with ECU but not signaling.  I did verify all wiring is
> 
> connected properly -  OBD power +/-, OBD K/L, OBD blink.
> 
>  
> 
> I don't want to just plug another ECU in since if wiring is incorrect and full voltage
> 
> on wrong pin could concievably be damaging the ECU.  So I checked all harness pins at
> 
> connector w/o ECU: 
> 
>  
> 
> First testing all 55 pins w/r ground no battery negative connected: Pins 7, 10, 14, 19,
> 
> 24, 26, 52 showed some connection to ground.
> 
>  
> 
> With battery connected: checked for voltages reveal: 12V on harness pin 18 - that is the
> 
> unswitched power supply so OK.   What did not make sense is that I saw 3V on pins 3 and
> 
> 27.  Both these lead back to the Fuel Pump Relay terminal
> 
> That corresponds to ignition on - I think, terminal 86 on the relay.  Some diagrams show
> 
> as 46.
> 
>  
> 
> Anyway, I'm wondering where that 3 V is coming from.  It is fairly consistant -
> 
> something in the car like a voltage regulator or the current that goes through a relay?
> 
> Is this normal?  That is if the key is off and voltage checked on the relay terminal 86
> 
> [no relay inserted] that voltage is around 3?  Would this cause a current drain or just
> 
> voltage present?
> 
>  
> 
> Also, I continued to test through all 55 pins again - when ignition switched on, I got
> 
> 12 V where there was 3V ( pins 3 and 270 and also on pins
> 
> 18.  8.75V on  terminal 50 (vehicle speed signal - from tach)? 
> 
>  
> 
> Weirdness.
> 
>  
> 
> Ben ]