I recently failed the CO2 portion of the emissions test with my 1990 Toyota 22R Pickup, 5 speed. Since then I have replaced the plugs, plug wires, rotor, distributor cap, set the RPM to 800, the timing to 12 degrees BTDC with vacuum advance blocked(believe this is correct since no sticker under hood) and rebuilt the carburator. The truck seems to be running well, but I would like to know if there is something else I should check that could be affecting the CO2 emissions before I get it retested. I have also noticed a hiccup, like it is is missing when cruising, not on acceleration, this was there before and after the work mentioned above. Any suggestions?

I recently failed the CO2 portion of the emissions test with my 1990 Toyota 22R Pickup, 5 speed. Since then I have replaced the plugs, plug wires, rotor, distributor cap, set the RPM to 800, the timing to 12 degrees BTDC with vacuum advance blocked(believe this is correct since no sticker under hood) and rebuilt the carburator. The truck seems to be running well, but I would like to know if there is something else I should check that could be affecting the CO2 emissions before I get it retested. I have also noticed a hiccup, like it is is missing when cruising, not on acceleration, this was there before and after the work mentioned above. Any suggestions?

new cat will make almost anything pass!

TONS of info here: http://board.marlincrawler.com/index.php?topic=1119.0