HC is 340 ppm vs a spec limit of 220, with a new cat and new O2 sensor. Th
is is at idle. At high rpm (2000) it passes the same limit. In this model
year/PCM, 128 counts is what later came to be called 0%. The scan tool is
a Snap-On MT2500. Yes, at temp, 200 F. Factory intake and air cleaner wit
h new filter. New plugs, wires, and ignition module. (These were replaced
before the new cat was put in because of bad ignition misfiring, so I don'
t think I killed the new cat.) Just put all new gaskets, o-rings, and fuel
pressure diaphragm in the TBI. It was amazingly clean, for not having bee
n touched in 360K miles. (The long block has only 140K on it and the plugs
always look very clean.) Short term trim does bounce around a little as it
should, staying close to 128 as the long term trim walks its way down mto
keep it so. The curious thing is the difference between LT trim behavior
in drive and in park, both at idle. PCM? How would I know?
Thanks for the input. Unfortuantely I don't have a gas analyzer. If I did
, I would have tried to see if I could measure HC before and after the cat
to see if it's bad, no?