[V8] The Audi Gods are giggling at me (still giggling...)

[Dave Saad]

That might have been me. I am running Audi ABS sensors that I got at the junk yard as timing and reference sensors. They have been in there for quite a few years now with no problem. Mounting them was not easy though - so if you can find other sensors where the only difference is the cable length then I would go that way. If you mount them too deep you will hit the reference pin or flywheel teeth. If you shear off the pin then you will not be happy.
I dissected my bad one and the failure is probably caused by heat cycles. The sensor is made of perhaps 1000 turns of super fine copper wire wound on a bobbin with a magnet core. Eventually the wire breaks when it expands (hot) and makes contact again when it cools. I am hoping the ABS sensors are better able to handle the heat cycles. So far so good.

A good way to test the sensor (and probably kill it as well) is take it out and put an ohm meter on it. Heat it up with a hot air gun and watch for it to go open. Just don’t over do it with the heat gun - they get pretty hot. Actually, a hair dryer may do the trick.

Dave

> On May 11, 2015, at 10:47 PM, cobram at juno.com wrote:
> 
> Flywheel sensor.  
> 
> Crank position sensor. The ECU only needs this signal for starting, it's
> heating up 
> and likely giving an open signal. 
> 
> If you look in the archives, someone had figured out that an
> (International??) truck ABS sensor was 
> identical except for alonger lead.
> 
> BCNU,
> Experience is the name everyone gives to their mistakes.
> 
> On Mon, 11 May 2015 21:30:29 -0700 John Bysinger <doog at bysinger.net>
> writes:
>> Ok, this time it's more of a snicker.
>> 
>> I've got a no-start issue now.  If she's cold, starts up 
>> immediately, no
>> problem.  I've probably had 20 starts since I woke her up from her
>> slumber.  Every time, barely a half second of cranking and runs.  
>> But twice
>> now, when at running temp, I stop at a store, off for maybe 5 
>> minutes, come
>> back, won't start.  It seems like a no-spark issue, but didn't have 
>> someone
>> with me to crank while I checked spark.  New battery, cranks strong 
>> without
>> issue, but I never hear it ignite.  Just keeps spinning.  But let it 
>> sit
>> for say 15-20 minutes, starts up perfect, like nothing was ever 
>> wrong.
>> 
>> I think the gods are testing me, or at least getting a good laugh 
>> out of me.
>> 
>> -John
>> 
> 
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