[T3] Bad day at the (FI) office

[Dave Hall]

Ignition on without the engine turning will either be powering the coil or
not, depending on whether the points are open or closed. It won't have done
any harm to the points either way.  Is the heel and cam lubricated?  High
performance ignition coils tend to produce more erosion of the points.

Keith says your sensor for AFR is not sited correctly (or is that someone
else?) - seems to me if he's right you're placing too much reliance on its
readings.  MPG over a decent distance must be a better guide.  Plug colour
too will help, as will feel of the engine response.

My FI Fastback performance is very sensitive to timing, but it has the twin
vac advance (as does my twin carb Variant, but that doesn't seem so
sensitive).  When it was hunting, I enrichened the MPS slightly, then
reduced it again a few months later when a CO meter showed it was around 1%.
It went back down to less than 0.5% and no hunting! 

Keep enjoying driving it, and let it grow old gracefully!

I used to worry about the sound of my 7-year-old Beetle engine 50 years ago,
so my parents bought me a Blaupunkt radio for my 21st birthday! A few months
later at 50,000 miles I had to have a new camshaft as two cam followers had
worn through to the oilway - expensive!  Ah, the joys of VW motoring back
then, and I am still committed to them!

Dave
UK VW Type 3&4 Club
===================

-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Daniel Nohejl
Sent: 29 March 2016 12:16
To: type3 at vwtype3.org
Subject: Re: [T3] Bad day at the (FI) office

snipped

Anyway, in general, things seem to be better. We went away over the weekend
and on the way out of town, we leaned out the MPS a wee bit closer towards
its original position. Our highway cruise AFR is kind of lean..anywhere from
14.5 to 16.5 but our MPG over the 260 miles was a modest 25.8. I imagine if
we were too lean, our MPG would have been much higher. 

Toward the end of the trip, I started noticing that the idle AFR went back
to rich even though we hadn't touched it again and that the idle sounded too
high. When we got home, we took out the dwell meter and timing light. First,
the idle was at 1020 rpm so we brought it down to 850 but it was unstable
and hunted slightly so we brought it up to around 900 which is where it
seems happiest. We noted that the dwell had changed from 48* to 52* in 1600
miles. I've never had that happen before. Also, the timing was a few degrees
advanced..closer to the second timing mark than the first. We tried to reset
the points but there was such a big tit on one side that it was hard to get
the feeler gauge through so we just put in new points and re-did the timing.
Once we did that, the idle AFR went from 11.5 to 13. Seems like the advanced
timing was messing up the MPS and the a/f mixture. 

I've yet to have a set of points go bad on me in only 1600 miles.
Admittedly, I only have about 70,000 miles of VW driving under my belt but
still..Part of me wonders if repeatedly having the key in the ignition in
the on position while toggling the fuel pump prime switch hastened the death
of these points. Maybe I can power the switch from an always hot fuse and
see what happens?


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