[s-cars] Stumbling still

[Bob Frizzell]

S-men,
I've finally fixed the stumbling problem and Paul was right, I had a sheared
key on the crankshaft pulley.  In fact, the crankshaft pulley wasn't torqued
to anything close to what it should have been.  I feel very fortunate to
have got to it before I had valves hitting pistons.  I now have a new timing
belt, idler, new pulleys, bolts, waterpump, seals, serpentine belt, and
thermostat, so that part of the engine should be good for a while.  Thanks
to all who helped me with this problem.
Bob 93//S4
----- Original Message ----- 
From: "Paul Gailus" <gailus at mindspring.com>
To: "Bob Frizzell" <bobfrizzell at shaw.ca>
Sent: Saturday, August 07, 2004 10:45 PM
Subject: Re: [s-cars] Stumbling still


> Bob,
> Possibly you could have a sheared key on the crankshaft
> sprocket that drives the timing belt. Apparently the camshaft
> position sensor (CPS) signal is needed to enable or "gate" the
> crankshaft position sensor TDC signal for the ignition to fire.
> If the sprocket rotates out of proper alignment, the timing
> window established by the CPS signal can shift so that the
> TDC signal is not properly centered inside this timing window.
>
> A number of listers have had sheared keys on the timing belt
> drive sprocket, but not always with a large enough
> sprocket rotation to cause a no-start condition.
> A good description of this problem for the Audi S2 engine
> (which has the hall effect sensor in a distributor at the back of the
> camshaft instead of at the front camshaft sprocket) is available at:
> http://www.picotech.com/auto/audi.html
>
> The CPS signals and TDC signals could be monitored on
> a scope to check for proper phasing.as described in this
> artivle.
>
> Before having these waveforms checked, you could try
> to verify that the marks on the camshaft sprocket,
> crankshaft sprocket, and the TDC mark on the flywheel
> can be aligned simultaneously to see if the crank sprocket
> has rotated out of alignment.
> The writeup by Fred Munro on replacing the timing
> belt at the following link has some good pictures for this:
> http://www.urs4.com/technical/repair/timing_belt/timing_belt.html
>
> Photos 4 and 5 on this web page show how the timing
> marks should be aligned:
> http://www.urs4.com/technical/repair/timing_belt/s4tbp4.jpg
> http://www.urs4.com/technical/repair/timing_belt/s4tbp5.jpg
>
> In photo 6 Fred could not find the mark on his flywheel which
> should be visible when the front timing marks were aligned,
> but maybe you can on yours:
> http://www.urs4.com/technical/repair/timing_belt/s4tbp6.jpg
>
> Paul
>
>
> ----- Original Message -----
> From: Bob Frizzell <bobfrizzell at shaw.ca>
> To: <s-car-list at audifans.com>
> Sent: Saturday, August 07, 2004 5:35 PM
> Subject: [s-cars] Stumbling still
>
>
> Dave, other great S-men,
>
> Well, car is running better I've still got a problem.  I'm still getting
CEL
> on briefly after WOT or close and the car feels like there is a boost leak
> or similar - it just doesn't build like it should.  So, to recap, I've
done
> the following:
>
> 1. Checked ignition parts and injectors
> 2. Put Stabilant on connectors
> 2. Replaced fuel filter
> 3. Replaced oxygen sensor
> 4. Pulled codes: 2113
> 5. Tech replaced camshaft position sensor and checked timing.
> Still stumbling
> Spent about $800 at this stage
> 6. Pulled out ECU, put Stabilant on connectors, checked wires, fuses
> 7. Remembered from previous work that wires to coil packs were looking bad
> (cracked insulation)
> 8. Taped up wires with Extreme tape ($10)
> Car runs significantly better but not quite right under WOT.
> 9. Used an ohmmeter to check continuity from middle pin in CPS connector
to
> pin 8 ECU connector - yes, we have continuity.
> 10. Pulled fuse 26 to reset ECU - code 2113 gone until first time at WOT.
>
> So, some questions,
> 1. If the tech didn't really check the timing and the belt slipped by one
> notch would it run as described?
> 2. Can I check timing without accessing the timing belt?
> 3. If I borrow an ECU out of another person's car and installed it in mine
> is there any chance  I could damage it (I wouldn't think so but?)?
> 4. Is there any chance a faulty coil pack or POS could give me a 2113
code?
> 5. Anyone ever have a similar problem where replacing the CPS didn't fix
it?
>
> Thanks again for all the help (I'm indebted)
> Bob 93//S4
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