1984 4k - no start

[Grant Lenahan]

Test port for a probe, pre-cat EGA.

Grant
On Aug 14, 2009, at 8:07 AM, Bares, Vittorio wrote:

> Yup, quattro. I see there is a bung on the end of the downpipe just
> before the cat - but no O2 sensor (seems to be capped)?
>
> I thought it might be a hot start - however, it doesn't always cold
> start either.
>
> Vittorio -
>
> -----Original Message-----
> From: Huw Powell [mailto:audi at humanspeakers.com]
> Sent: Thursday, August 13, 2009 5:15 PM
> To: Bares, Vittorio
> Cc: Ben Swann; quattro at audifans.com
> Subject: Re: 1984 4k - no start
>
>
>> As for the O2 sensor - err, uh - ETKA says it has one - I'd expect it
> to
>> be on the exhaust downpipe somewhere - but I don't see one - this is
> an
>> '84 - any ideas?
>
> It's mounted on the top of the front of the catalyst.  This is a
> quattro, right?
>
>> I'll move one of the additional battery to motor grounds to the
> firewall
>> (Huw, I think that is what you were intending when you mentioned that
>> the one to the motor is for the starter?) - read that in one of the
> old
>> '4k no start' threads from like 1998.
>
> Yes, the starter is the heaviest load the battery ever runs, hence the
> hot wire directly to it.  It's nice to have a fat ground to a tranny
> bolt to complement it.  And see below...
>
>> Hmm - I thought - perhaps this is heat related? So, I ran the car for
> a
>> while, no more than 5min - turning it off, then on again, 3rd time I
>> tried this - no start. Had to leave to return the borrowed parts so
>> didn't have a chance to go through the tests again.
>>
>> When I got back, sure enough it started right up - but this time on
> the
>> first attempt of turning it off and on - it didn't start.
>
> OK, so potentially the whole problem is a hot start one?
>
> Those early 80s Audis have quite a few hot start issues, some of which
> they were beginning to address.
>
> One thing you might want to do is measure the current the starter is
> drawing (most competent garages should have a clamp-on current meter
> that will do this).  My coupe once had a bad hot-start problem, turned
> out the starter was drawing ~200 amps, in turn pulling the battery
> voltage too low to run the CIS.  New starter made problem go away
> completely.
>
> -- 
> Huw Powell
>
> http://www.humanspeakers.com/audi
>
> http://www.humanthoughts.org/
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>



Grant Lenahan
glenahan at vfemail.net
(201) 602-4702 mobile