running rich under boost

[Nick Craft <ncc@scr.siemens.com>]

Can someone tell me if a voltage of 1V from the OXS means
"rich" or "lean"?

I've been getting a "running rich" kind of smell from my
car when running hard. Today I hooked up a portable
scope to the OXS & went for a drive. The CIS is doing its
thing, flipping between 0.1 & 1V at idle and cruising, but
when the turbo is on boost, the thing goes to 1V continuous.
This is with the WOT/idle switch disconnected.
The idle CO & duty cycle are on spec.

So, looks to me like something's leaking air under boost pressure.
Can't find any leaky hoses though. How about injector seals
as a possibility?

OTOH, maybe its just normal to go rich under boost? Somehow I
doubt it, esp. as the WOT enrichment was disabled for my tests.

Can someone who understands these things make some suggestions?

The car's an '88 5KCSTQ Avant.

Cheers,
Nick Craft