Hello all,

I have a 1991 Toyota 4x4 4 cyl 5 speed that didn't pass emissions this time through. I did the normal tune up, fuel filter, air filter, plugs, wires, cap and rotor. The cat is about 1.5 years old since someone needed my cat more then I did. Hydrocarbons and CO2 is over the fail numbers. Worst thing about this is that my reg is unrenewable until this is passed. I drive the truck everyday to my full time job then to my business after that. Any help would be greatly appreciated. Thanks

 

You're running rich. Not enough oxygen to burn up the HC and turn the CO to CO2.

Yes, CO, not CO2. I really doubt CT has a CO2 limit. (Are they different? You breath CO2 every day. CO will kill you in minutes.)

The Technical Article on Emissions Analysis found here: http://www.autoshop101.com/ is instructive.

Can't renew your registration while failing smog? Imagine that ...

 

I went through hell one year trying to get mine to pass.

My advice:

Drop it off at the mechanic and come pick it up when they call and say they got it to pass.

 

The good news is they'll probably give you an exception once you show them reciepts for enough cash thrown at the problem.

Check the timing, computer can only adjust so far.
Most overlooked item in a tune up is ... PCV.
Make sure the PAIR is sucking not blowing.
Clean the terminals on the Oxygen sensor.

*edit*
Reset the computer if you just switched back to high octane.

 

I agree with CO_94_PU's comment... check your local law throughly... here in TN in very very fine print at the bottom (after $200.00 (costs based on age) and the problem is not resolved you may apply for an 1yr exemption), that means take it to the State Mechanic with receipts in hand, they will confirm the parts are installed, make recomendations for futher repairs, and grant the waiver.
Now for TN we have one State Mechanic for 5 counties, 4 week back log of appointments, grrrrr