> My  `84 has an inconsistent idle speed... it revs (or surges)
> every 3 or 4 seconds.  I can't get an IM test because of the
> condition -- not to mention the detrimental effects on gas
> mileage...

> Does any one have any thoughts?  A friend with a similar problem
> suspects the "brain box" -- Anyone know of a location for these?
> Thanks for any help.

How was it... answers: $1, correct answers: $10, dumb looks: free.
:-)  I do have some thoughts though:

Your idle may be set too high, so the ECU compensates for a few
seconds, then the battle starts over.  I had this and set it back a
bit (big screw on the throttle body).

Another possible problem is that your idle enrichment switch maybe
maladjusted or busted.  I found readjusting mine made the idle behave
_much_ better.  Kudos to Darrell Boehler's Digifant tool for finding
this.  A quick way to check is to turn the engine off, manually move
the throttle away from idle position, then let it return to idle
position.  You should hear a little click as the switch is depressed.
 On your '84, you should actually be able to see the switches; one is
for idle, the other is for full throttle.  On the '86up, it's
underneath.

You should also check the continuity of the switch, but if it's
really depressed, it should be working.

When I fixed this, it stopped the minor hunting that still seemed to
go on at idle.

YMMV.

-Karl

'87 Vanagon GL Weekender "Beverley"; Trexlertown, PA
http://www.enter.net/~bloss/vw/
VW shop list: http://www.enter.net/~bloss/vw/vwshops