[s-cars] 1993 S4 miss firing

[Eric_R_Kissell at whirlpool.com]

"Jim Dupree" <jdupree914 at sbcglobal.net> wrote:

My 1993 S4 has a miss under moderate load. It started out mostly between
1900 and 2300rpm but it is getting worst. At idle is misses periodically.
At
part throttle (1/2) accelerating will 1-3 times between 1800 rpm and 2200
rpm. Misses less cold. If it starts missing and I give it full throttle it
starts missing a lot, almost a shutter. If I keep it above 2100 rpm I can
drive almost completely without a single miss.
Connected my VAG COM and no trouble codes stored, O2 learning value
indicates only very slight lean condition and everything else is within
specs. I have not measure the CO%. The miss feels like an electrical miss
when between 1800 and 2200, very sharp individual misses. Under full load
when I get it to shutter it feels like all cylinders are missing partially.
I pulled the coil packs off the head checked for corrosion or loose
connections and measure the plug connectors, all are approx 5k ohms. Pulled
the spark plugs and they look OK, not great but OK. these are the bosch
Platinum DPO plugs that are very expensive or I would have just replaced
them, I may yet. I don't know how to test the coils short of swapping out
with good ones.
It is a 93 with 210k miles, so there are lots of possibilities.
Any ideas?
Thanks
Jim