I'll second the O2 sensor. Last winter we had exactly
the same symptoms, and were running a splice-in type
02 sensor.

I overwrapped the splice in electricians tape, put a
layer of silicon sealant over the whole thing paying
particular attention to the ends, and then another
layer of tape. No problem at all after than, in the
identical situations, over the last nine months.

--- Karl Mullendore <groups@WESTYVENTURES.COM> wrote:

> I've diagnosed two vans with same symptoms, both
> Syncros on the trail,
> after splashing through puddles the OXS CONNECTOR
> and wire was soaked,
> the [small] change in the voltage reading caused by
> the moisture track
> caused the ECU to adjust the fuel mixture
> rich...loss of power and
> stumbling. I'm not a guesser or theorizer, but a
> experienced mechanic.
> The coolant temp sensor cannot be disconnected and
> the engine run normally.
>
> Yes, shorted plug wires, especially the plug caps,
> will cause the
> symptom too, however weren't these replaced? And it
> would show up as a
> solid miss if so.
>
> Daniel L. Katz wrote:
> > richard:
> >
> > most obvious possibility is problem on high
> tension side of ignition, such
> > as mositure and/or carbon tracks in distributor
> cap, arcing between spark
> > plug wires and ground (might see sparks outright,
> or glow around wires, at
> > night), or, even if not root cause, fouled plugs.
> >
> > O2 sensor very unlikely here, and it can be
> temporarily disconnected in
> > any case to eliminate possibility. ditto temp
> sensor. O2 sensor and,
> > though to a much lesser extent, temp sensor, are
> high impedence, low
> > current devices, so in this context a little
> contact resistance is
> > irrelevant.
> >
> > dan
> >
> >
>

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