V8 Engine Problem

[Weiss, Dave]

Thanks for all the responses so far!  Trying to compile/condense here...

Matt Beaubien wrote:
>>
What sort of leakdown numbers are we talking about? 5%? 10%? 40%?  None of
the plugs have black deposits from burning oil?  Could indicate that the
exhaust valve guides/seals are shot, and the oil is entering the exhaust
port and not the chamber.
<snip>
Leakdown and compression tests can't tell you anything about the condition
of the oil rings.  You can have great compression and leakdown numbers but
still burn lots of oil if the oil control rings are gummed up.  Ring gaps
that are lined-up will not produce "significant leakdown" values.
<<

Mech said about 30% leakdown for the "bad" cylinders.  I didn't witness it,
would expect some variation.  Air seems to be going down rather than out the
valves.  No black deposits, but the three w/ leakdown had a little more
brown.  I'm puzzled that compression is good in all cylinders, close to
theoretical, but leakdown is in 3 cylinders.

=======
Differences so far between manual and auto are:
	rear plate
	timing belt guide
	cams
	computer (didn't Steve Buchholz write once that A/T computer works?)

Rob Beatty wrote:
>>
You must also put in a guide for the timing belt on the standard trans
motors to keep the timing from jumping teeth if using the engine for
braking...
<<

Dave Head wrote:
>>
John Karasaki has proven you can swap in an auto - but change over the cams
- they're different auto to stick.
<<

=======
Tom Jervis wrote:
>>
How do you know the air is going into the crankcase?
<snip>
It does not seem likely that this usage would be poisoning the O-2 sensor.
Does it indicate anything on the diagnostic codes?
<snip>
I suspect something else is wrong  that is causing the miss and a full
diagnostic is called for.  Check ign wires, for example.
<<
I assumed poisoning because of oil consumption and residue in tailpipe.  O2
sensor code just occurred, and now I wonder if wrench #1 screwed up wiring
when shorting it to see if richening would stop the miss (it did).

The mech heard the air by pulling the dipstick.

Previously in looking for the misfire, never any codes 'til now.  Had
replaced lambda sensor w/ Bosch OE, caps and rotors too, no effect on
misfire but gas mileage improved.  Injectors flow tested ok.  Misfire is on
lift/light throttle, so I didn't suspect ignition wires.  Sometimes misfire
goes away for days, sometimes it's ~every other lift throttle, and now more
on light throttle as well.  There is an Audi TSB from about 1993 on V8
engine performance, and it mentioned a bad Hall sender would create a
condition like this-- car starts, good power, occasional misfire-- FI just
360 deg off from the ignition.  But I would have expected a fault code.