Tom, a couple years back i had an intermitant misfire problem with my 87
that caused the van to shudder and have no power.  The ignition system
was working fine, the injector wasn't.  A mechanic put his special
stethescope on it an verified this.  It wasn't cause the intector was
clogged, but that it wasn't getting a signal, so he put some contact
enhancing fluid (similar to audiophyle 'Tweak') on the contacts after
cleaning them with emery cloth and the problem was solved and hasn't
reoccured.

BTW, replace your OXS....without it the ECU can't fine tune the mixture
setting and you're blowing high amounts of either hydrocarbons or NOx
out the tail pipe.  $40 and some splicing.

later,
Fred

Tom Ervolina wrote:
>
> My 87 Vanagon will run fine for about 20 mins and then it starts to misfire and
> lose power ... especially noticeable on the hills.  The misfiring seems to then
> become intermittent.  The misfiring causes the engine to vibrate as if its out
> of balance or one cylinder doesn't fire.  It's sputter as if it wants to run
> smooth.  If I ease back on the gas, it sometimes will cause it to snap out of
> it and run smooth, but usually I'm climbing and as I give it more gas, it'll
> misfire again. It is not directly correlated to operating temp, as the temp
> seemed to stabilize at normal before the misfiring began.  It started a few
> days ago and I opened up the distributor and cleaned up significant deposit
> from the rotor and cap arc points.  I thought for sure that that would fix it,
> but it didn't.  I also pulled the spark plugs and cleaned and gapped them.
> They looked fine ... a bit of brown but otherwise seemed ok (running hot?).  I
> put in some techron and am running this tank down in case there's some water in
> the gas, but i doubt this will help.
>
> If anyone has experienced this and can point me to some likely culprit, I'd
> appreciate it.  Other data points: 137K , new heads about 4K ago.  When it runs
> well, it really runs very well.  The O2 sensor light came on about 15K ago and
> I never replaced it.  Thanks for any help.
>
> Tom Ervolina
> Enterprise Solutions Research
> IBM
> Yorktown Heights, NY
> ervolina@us.ibm.com