This is the third emissions test I've failed. The only problem is idle hydrocarbons.

I started off with headers and catback, an O2 sensor, synthetic oil change and new air filter. The first test was about 260/130.

After that, I replaced cap, rotor, wires, plugs, PCV valve, reset the ECU, and ran it for a couple days. Retested at 240/130.

Now I've replaced the catalytic converter. It failed again today at 190/130.

At this point I qualify for a waiver, but its just the darned principle of the thing! The car seems to run perfectly. Even the emissions mechanic didn't have a clue. I'm stumped. The waiver is $75 but I'd rather spend that money on something that will make the car run better than just pay it to the state.

Anybody have any hunches or wild-assed-guesses?

 

it seems like your burning off too much CO2.

Wild Guess?
clean yoru IAC valve and throttle body

check to see your fuel injection cleaner is working properly

 

I did three more things tonight: changed the fuel filter, bled air out of the coolant system, and drained out 1/2 qt of oil.

I suppose the IAC valve would be the next thing to check. I'd thought about that myself. There seemed to be a good bit of air in the cooling system though. Perhaps that might make a difference.

Per the emissions mechanic's advice I added a bottle of Lucas fuel treatment, and put in 5 gallons of ultra-93. I'm taking it back in tomorrow for its final retest and if it fails I'll just pay for the stupid waiver. I'll mess with the IAC valve next year.

 

Do you have heat shields on your converter and the pipe all the way back to the engine? Those are actually there to make the converter work better.

Trying to clean the injectors is a good idea. It's not hard to pull them and clean them off of the car. Also check the fuel pressure.

 

I passed! I did stop and clean the IACV screen with some injector cleaner spray on the way over though. I simply removed the two bolts, pulled it free, gave it a couple shots, and bolted it back down. The screen was black and maybe half plugged before I sprayed it, and it cleaned up nicely.


My final idle HC score: 60/130! W00T!