Hi George,
    You are probably correct in your short trip low mileage scenario.  Our vans run in open loop until the coolant temperature 2
sensor voltage reads 0.3 -0.4 volts. Then it goes into closed loop and the mixture is leaner .  Another indication is closed loop
happens when the engine  temperature gauge is still on the big white area and just ready to start moving from it.  Or another
indication is under no load condition if you hold your accelerator very steady at 2k-3k rpm when in closed loop your rpm will cycle
slightly higher to lower as the ecu constantly hunts for the perfect mixture going from rich to lean. When it is below about 30
degrees F (I started to say very cold but knew many would roll over laughing)   the temperature 1 sensor (air temp) further enriches
the mixture in open loop.  Most vans seem to go into closed loop in about 4 miles at 20 degrees F.
    After I repair and test ecus as best I can on the bench I put them in my van or double cab and cruise around checking  for
slight anomalies.  I have seen lots of warm up cycles.

Darrell

----- Original Message -----
From: "Craig Spaeth" <spaeth@GORGE.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, January 18, 2001 11:33 PM
Subject: Bad in town Mileage

> Our 90 Multi Van automatic is getting lousy mileage around town. It gets between 12-15mpg. Out on the road we see between 18-20. I
am wondering if this is
> caused because of our small town driving habits. A lot of the trips are between 1-3 miles so it never gets all the way warm. I am
thinking that it may still be
> in the warm up richening cycle and never really get a chance to get out of that. I picked up a set of plugs, cap, rotor, and air
filter, just to see if that
> helps. Anyone have any tips for this kind of driving?
> thanks in advance,
> Craig
> the Gorge VW club
>