90q missing on cyl 5...ideas?

[Dave Hord]

Hey gang...got a problem with the q.

The car:  1989 90 quattro
The engine: 10 valve, Naturally aspirated. Stock.
The problem:

Dry weather -> Car drives perfectly fine.
First Snow/Freeze -> Car was fine, halfway home car began to idle like it had a
REALLY lumpy cam in it. Hit the gas...car almost dies, backfires in the
manifold/downpipe...then suddenly revs up and away you go.  Keep it above
3000rpm otherwise car drives like it's missing.

At home I checked the wires, plugs, cap and rotor.  Cylinder 5 (closest to
firewall) has spark, but does not have a combustion reaction.  This is evident
as car idles no different if you pull the 5th sparkplug wire.  It idles rougher
if you pull any other wires.

Tossed the car in the garage for the night, put some gas-line anti-freeze in
the tank. The next day was above freezing...no problems.

No problems all week. I'm now on my third full tank of gas.

It snowed today -> but above freezing snow.  Car ran great for an hour...then
the problem returned. I have parked the car outside tonight...partly to tempt
fate, partly to see if warming up/drying out the car solves the problem, or if
it just needs to 'sit'.

Any ideas?

Current thought is perhaps an electrical problem with the 5th injector..perhaps
effected by water/dampness?

TIA
Please reply directly, as I'm not recieving list messages at the moment.
-Dave







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89 90q  300,000km!!!!!!!!
http://home.the-wire.com/~spokes