Greg Reed

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Well, actually it will start, but only on about 1% of the attempts I make.
A friend who's much, much smarter about all things mechanical than I has
been helping me troubleshoot this problem for the better part of a week, and
we're mostly stumped.

The problem is a lack of spark. On those rare occasions when we actually
get spark, the car fires right up. And since the spark is plenty strong
when it's there, we've been looking for problem either with the ECU itself
or with one of its inputs. (Yes, we've checked all the connections in the
ignition system, checked the distributor rotor and cap, and so on.)

Near as we can tell, the problem is the signal from the crank reference
sensor (located right next to the RPM sensor on the driver's side of the
block) being too weak. We've tried replacing the sensor, but the signal is
still weaker than my brainy friend thinks it should be. So we rotated the
flywheel until the pin that this sensor is supposed to react to was right
under where the sensor goes, put some putty on the end of the sensor, and
stuck it in its hole to check the clearance. We actually got a bit larger
gap than the .040 that the Bentley manual specifies, but close enough that
it shouldn't be a problem -- say, about .060.

But what we noticed that seemed a bit odd was this: The indentation from
the pin in the putty only went about halfway across the "business" end of
the sensor. It would seem to me that in order to generate a decent signal,
this pin should extend all the way across the sensor's surface as it whizzes
by. There really isn't any wiggle room in which to adjust the sensor so as
to move it closer to the flywheel and therefore get a better reaction from
this pin, so either our observation (about the pin only coming halfway
across the bottom of the sensor) is normal, or there's something wrong with
the pin. We didn't see anything in the Bentley manual about this particular
detail (doesn't mean it's not in there somewhere), so I'm hoping that
somebody here can help out. FWIW, the starter was replaced (by a mechanic)
just prior to this problem cropping up, so it's not completely impossible
that this pin was somehow damaged in the process.

Can any of the gearheads here confirm whether our observed alignment of the
pin with the crank reference sensor is normal or not, so we can either
pursue fixing it or move on to something else? (And we're pretty much
completely out of "something else's" at this point.) And does anybody have
any other ideas as to what might be the problem?

Many thanks in advance!!

- Greg

--
1976 Cadillac Fleetwood 9-passenger sedan
(for sale: http://www.dataspire.com/caddy)
1989 Audi 200TQ sedan
2000 Oldsmobile Intrigue
2001 Chevy Astro AWD (wife's)




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TonyJ

There have been several experiences like this posted at the AudiWorld
forum for type 44s lately. You may want to check there and search the
previous threads or ask the question. Lot of talent there.

http://forums.audiworld.com/v8/


> Can any of the gearheads here confirm whether our observed alignment of the
> pin with the crank reference sensor is normal or not, so we can either
> pursue fixing it or move on to something else?

The spec that you are observing has, again, been discussed at AudiWorld.
I do not know it off hand but it should be easy to find references to it
at the forum.

> (And we're pretty much
> completely out of "something else's" at this point.) And does anybody have
> any other ideas as to what might be the problem?

Hall effect module in distributor have an intermittent?

I thing that your suspicion about ECU inputs being the cause is most
likely the issue.

Tony
'91 100Q 5spd

Steve Sears

Greg,
Have you tried reading the fault codes in the ECU? see
www.sjmautotechnik.com about fault code retrieval - what do they say? It's
possible that the pin got bent if the old starter self-destructed..? You
can remove the new starter (it's a pain, but at least the nuts aren't
siezed) and look at the pin to see if it's been hit/bent/???.
Cheers!
Steve Sears
1987 Audi 5kTQ
1980 Audi 5k
1962 and '64 Auto Union DKW Junior deLuxes
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"Greg Reed" <inet_user@hotmail.com> wrote in message
news:3f96abc5$1@post.newsfeed.com...
> *** post for FREE via your newsreader at post.newsfeed.com ***
>
> Well, actually it will start, but only on about 1% of the attempts I make.
> A friend who's much, much smarter about all things mechanical than I has
> been helping me troubleshoot this problem for the better part of a week,
and
> we're mostly stumped.
>
> The problem is a lack of spark. On those rare occasions when we actually
> get spark, the car fires right up. And since the spark is plenty strong
> when it's there, we've been looking for problem either with the ECU itself
> or with one of its inputs. (Yes, we've checked all the connections in the
> ignition system, checked the distributor rotor and cap, and so on.)
>
> Near as we can tell, the problem is the signal from the crank reference
> sensor (located right next to the RPM sensor on the driver's side of the
> block) being too weak. We've tried replacing the sensor, but the signal
is
> still weaker than my brainy friend thinks it should be. So we rotated the
> flywheel until the pin that this sensor is supposed to react to was right
> under where the sensor goes, put some putty on the end of the sensor, and
> stuck it in its hole to check the clearance. We actually got a bit larger
> gap than the .040 that the Bentley manual specifies, but close enough that
> it shouldn't be a problem -- say, about .060.
>
> But what we noticed that seemed a bit odd was this: The indentation from
> the pin in the putty only went about halfway across the "business" end of
> the sensor. It would seem to me that in order to generate a decent
signal,
> this pin should extend all the way across the sensor's surface as it
whizzes
> by. There really isn't any wiggle room in which to adjust the sensor so
as
> to move it closer to the flywheel and therefore get a better reaction from
> this pin, so either our observation (about the pin only coming halfway
> across the bottom of the sensor) is normal, or there's something wrong
with
> the pin. We didn't see anything in the Bentley manual about this
particular
> detail (doesn't mean it's not in there somewhere), so I'm hoping that
> somebody here can help out. FWIW, the starter was replaced (by a
mechanic)
> just prior to this problem cropping up, so it's not completely impossible
> that this pin was somehow damaged in the process.
>
> Can any of the gearheads here confirm whether our observed alignment of
the
> pin with the crank reference sensor is normal or not, so we can either
> pursue fixing it or move on to something else? (And we're pretty much
> completely out of "something else's" at this point.) And does anybody
have
> any other ideas as to what might be the problem?
>
> Many thanks in advance!!
>
> - Greg
>
> --
> 1976 Cadillac Fleetwood 9-passenger sedan
> (for sale: http://www.dataspire.com/caddy)
> 1989 Audi 200TQ sedan
> 2000 Oldsmobile Intrigue
> 2001 Chevy Astro AWD (wife's)
>
>
>
>
> -----= Posted via Newsfeed.Com, Uncensored Usenet News =-----
> http://www.newsfeed.com - The #1 Newsgroup Service in the World!
> -----== 100,000 Groups! - 19 Servers! - Unlimited Download! =-----
>

Petkan

Before you get too far with ignition, you can check if the fuel pump
(pressure) is ok.
I had intermittent stalling problems and ultimately had the pump replaced.
In some cases you can try to force drive the pump prior to cranking (to
build pressure).
It is done by unplugging the fuel pump relay and jumpering its wide slots.
By doing so the pump is constantly running (for the duration of the
experiment). Let it pump for a minute and then crank. It it starts - the
problem is low fuel pressure.
Plamen, Toronto
"Greg Reed" <inet_user@hotmail.com> wrote in message
news:3f96abc5$1@post.newsfeed.com...
> *** post for FREE via your newsreader at post.newsfeed.com ***
>
> Well, actually it will start, but only on about 1% of the attempts I make.
> A friend who's much, much smarter about all things mechanical than I has
> been helping me troubleshoot this problem for the better part of a week,
and
> we're mostly stumped.
>
> The problem is a lack of spark. On those rare occasions when we actually
> get spark, the car fires right up. And since the spark is plenty strong
> when it's there, we've been looking for problem either with the ECU itself
> or with one of its inputs. (Yes, we've checked all the connections in the
> ignition system, checked the distributor rotor and cap, and so on.)
>
> Near as we can tell, the problem is the signal from the crank reference
> sensor (located right next to the RPM sensor on the driver's side of the
> block) being too weak. We've tried replacing the sensor, but the signal
is
> still weaker than my brainy friend thinks it should be. So we rotated the
> flywheel until the pin that this sensor is supposed to react to was right
> under where the sensor goes, put some putty on the end of the sensor, and
> stuck it in its hole to check the clearance. We actually got a bit larger
> gap than the .040 that the Bentley manual specifies, but close enough that
> it shouldn't be a problem -- say, about .060.
>
> But what we noticed that seemed a bit odd was this: The indentation from
> the pin in the putty only went about halfway across the "business" end of
> the sensor. It would seem to me that in order to generate a decent
signal,
> this pin should extend all the way across the sensor's surface as it
whizzes
> by. There really isn't any wiggle room in which to adjust the sensor so
as
> to move it closer to the flywheel and therefore get a better reaction from
> this pin, so either our observation (about the pin only coming halfway
> across the bottom of the sensor) is normal, or there's something wrong
with
> the pin. We didn't see anything in the Bentley manual about this
particular
> detail (doesn't mean it's not in there somewhere), so I'm hoping that
> somebody here can help out. FWIW, the starter was replaced (by a
mechanic)
> just prior to this problem cropping up, so it's not completely impossible
> that this pin was somehow damaged in the process.
>
> Can any of the gearheads here confirm whether our observed alignment of
the
> pin with the crank reference sensor is normal or not, so we can either
> pursue fixing it or move on to something else? (And we're pretty much
> completely out of "something else's" at this point.) And does anybody
have
> any other ideas as to what might be the problem?
>
> Many thanks in advance!!
>
> - Greg
>
> --
> 1976 Cadillac Fleetwood 9-passenger sedan
> (for sale: http://www.dataspire.com/caddy)
> 1989 Audi 200TQ sedan
> 2000 Oldsmobile Intrigue
> 2001 Chevy Astro AWD (wife's)
>
>
>
>
> -----= Posted via Newsfeed.Com, Uncensored Usenet News =-----
> http://www.newsfeed.com - The #1 Newsgroup Service in the World!
> -----== 100,000 Groups! - 19 Servers! - Unlimited Download! =-----
>