YADA.............I like it! lol
Did you install new GOOD spark plug wires, cap and rotor also? You have to get the ign system working very well, so checking the ign. coil is usually a good idea too. Which spark plugs did you install? Bosch W7DC? I have had very good success with Bosch Caps and rotors, but limited success with Bosch spark plug wires with the Rabbits. Strange that I have found 2-3 bad new sets!!!
Observations and ramblings......................... Usually retarding the ign. timing a little will reduce the HC some or increasing the CO will also usually reduce the HC some. So what is the ign. timing set at and does the vacuum advance work on this distributor? Does it only have 1 vacuum hose to the distributor? I have seen the mechanical advance stick in some distributors too!
Important.........What did you set the freq valve to on the dwell meter? What is the max CO that your engine can emit? Also increasing the CO some might reduce the NOx too.
CO did not go down during the 25mph stage of the first test. That is interesting if the 02 sensor system is working!
HCs and NOx went up in the second test but at least the CO went down in the
25mph stage of the second test. NOx can be created by a hot exhaust and some vehicles had an EGR system. I forgot if your '81 has one, but I think not.
There could be vacuum leaks around the engine and especially at the fuel injector seals. Spray some carb cleaner at the FI seals and note the engine rpms.
some light reading............
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