a little help please? - na l5 missing...

[Huw Powell <human@nh.ultranet.com>]

No, my engine hasn't disappeared! - my 82 Coupe seems to have developed
a bit of a miss.  I suppose it could have been creeping up on me but
today I noticed it quite a bit.  Prominent around 2300-3000 rpm with no
load, accompanied by a little backfiring in the exhaust pipe (yikes!). 
I suspect the plugs, they're pretty old Bosch platinums, but yanking
individual plug wires didn't yield any obvious bad cylinders.  The gaps
on the two I checked looked ok.  Plugs did look old though (they are...)

Timing was +20 deg, I backed it off to +16, now it doesn't backfire but
it's a lot rougher in the low rpm (<3k) range.  Duty cycle hovers around
48%, OXS output 300-600 mV (seems a tad low...), temps and idle fine. 
Cap and rotor almost new, Bosch (yuk) wires seem ok.

I guess I'll throw a new set of plugs in tomorrow, I'll try the W7DTC's
I guess, though I've always liked the platinums.  Hope that cures it, in
the meantime, any ideas, suggestions, or especially btdt's will be
appreciated.  Suppose I'd better try to search for cracked vacuum lines
as well.

Thanks!

-- 
Huw Powell

http://www.thebook.com/human-speakers/audi-main.htm