I don't know if the '83 aircooled had the same setup, but on our
Digifant, the throttle switch was maladjusted.  One of the things the
throttle switch tells the ECU is when the throttle is at idle.  At a
certain RPM signal (2500 perhaps), the ECU shuts off FI.

When the throttle switch was not giving the idle signal, the van
would backfire when coasting down a hill because the FI was not shut
off.  Setting the switch correctly solved the backfiring problem.

-Karl

Karl and Kristina Bloss, Trexlertown, PA
'87 GL Weekender  "Beverley"
Mechanic list: http://www.enter.net/~bloss/vw/vwshops
Busses by the Trail - Oct 15-17, 1999: http://www.enter.net/~bloss/vw/bbtt
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