FAILED EMISSIONS 5kcsq Please Help

[John Larson]

"There are three things that we used to always do (Toyotas, VW's, Hondas) to
pretty much guarantee a pass:

1a) Fill up with Premium gas.
1b) Change the oil
2) Change the spark plugs
3) Get the thing DARN hot"

While some of these are good ideas, one is MOST ASSUREDLY not.  The higher
the octane, the poorer the burn, especially at idle.  You want to run the
lowest octane the car will stand for an emissions test.  Better burn = lower
HCs.  Hasn't anything to do with the CO%/volume.  Spark plugs also have zero
affect on the CO.  Big effect on the HCs.
Now.  On to the real problem.  If the mixture is THAT high, there are
several things to check.  First, the timing and idle speed need to be set to
specs, then the coolant temp sensor for the integrated Lambda system needs
to be tested.  Unplug the O2 sensor when the car is hot and see if it cleans
up.  Bad O2 sensors often make the engine go full rich. Test the output
voltage for both voltage and rapid fluctuation.   Make the fuse for the FI
system, often mistaken for a spare, is in there (side of the fusebox).  Once
those items are done, you can simply adjust the mixture with the little
screw in the airflow meter, right next to the fuel distributor.  Adjusting
it without verifying the other things can be a BIG mistake.  Follow the
procedure in the Bentley.  A catalyst, BTW, has relatively little effect on
the CO, and the same is true for engine oil dilution.  Both affect the HCs
big time.

HTH, John