High NOx indicates one or more of three things: overly advanced timing,
lean mixture, worn out catalytic converter.

I liked Bob's suggestion of setting the timing to 0 deg BTDC. While
you're at it, I've got a few spare carbs and intake manifold.. maybe you
could work around the problem THAT way too. Geez. It's as if nobody
remembers what California air looked like in the 60s... and no.. the pot
did not contribute nearly as much to the photochemical smog as all the
cars did. And you know, that extra pollution doesn't just disappear... we
all get to breathe that crap.

*sigh*

It's just not that hard, or expensive to get a 240 to pass smog..
especially in California where, as you pointed out, they will provide you
with extra money/an upper limit for repairs required to get a car to pass
smog.

If your car is running lean there are a bunch of things to check. The
easiest to check would be the vacuum hoses and intake ducting. The vacuum
hoses get dry and crack with age, the intake ducting often becomes soaked
with oil.. the results are essentially the same.. holes where there
weren't before.. and extra unmetered air into the engine. If there are
any hoses that aren't connected to something, check for a fitting that's
missing a hose. Theoretically your air mass meter could be on its way
out, but this is one of the last things I'd suspect.

The next thing that would cause your car to run lean would be a lack of
fuel. That could include worn fuel pumps (main, in-tank, or both), a fuel
pressure regulator that's restricting flow, a clogged fuel filter, etc.
These are somewhat unlikely, but if your fuel pump is making scratching
noises, or humming loudly, it may very well not be supplying enough fuel.

The timing is the next thing that would cause real high levels of NOx.
Your base timing could be really far off, or the ignition computer could
be advancing it way too much. If your base timing is off, just re-set it
(it should probably be around 12deg BTDC). It's pretty unlikely that your
ignition computer is advancing the timing too much, however if you've got
the Chrysler ignition setup (white distributor cap)... your car runs with
a really lean mixture and super advanced timing.. which promotes high
levels of NOx in your exhaust. This wears the catalytic converter
quickly, compared to more sane levels of ignition timing, for minimal
benefit. If you have the Chrysler ignition setup you could plug the
vacuum line going to the ignition computer, and the computer will retard
the timing to a more sane level... and probably allow your car to pass.

All of the above problems are pretty cheap to fix (even the AMM is cheap,
used) and worth looking at.. as with a little guidance, you could easily
fix them yourself if you're handy with a screwdriver.

Or your catalytic converter could be bad.. worn out really. If it's the
original one, it's almost certainly due for a replacement. Look around
for a decent independent exhaust/muffler shop to do the work (unless you
don't mind mucking with lots of rusty metal).

- alex

'85 244 Turbo
'84 245 Turbo