Hi all.

Today I failed only the idle CO test on my Washington state emissions test. I'm hoping someone can give me some better insight on the problem without me wildly guessing.

The numbers, in the form of "result[limit]":

Cruise Limit HC(ppm) 41[150] PASS
Cruise Limit CO(%) 0.04[1.1] PASS
Idle Limit HC(ppm) 174(220) PASS
Idle Limit CO(%) 1.9 (1.2) FAIL

From the numbers above, not including Idle CO, everything looks fine. The cruising CO is very far below the limit, however the idle CO is about 50 times higher than cruising, making it FAIL.

My question, is how can I fix this or find out what is going on. Here are some non-regular things that may have affected the car?:

1) Changed O2 sensor about 1 year ago. The check engine light came on, so I replace the O2 sensor with a part I got online. Check engine light went away, so seemingly fixed.

2) Car sat in storage for 5 months, and went to inspection immediately after. Was running for 2 hours on the highway before the inspection.

3) Haven't changed the oil yet since it has been in storage (I plan on doing that soon).


Anyone have any ideas why the IDLE CO is so high?

Thanks for all the help.

 

Your Idle HC seems a little high. Could be an incomplete burn situation. I would check the ignition timing. Set it to full allowable advance (there should be +/-2 degree allowance). How are your plugs?

 

Thanks for the help kchungb17a.

I was going to try your point next, after I did the following: I had talked to a local auto parts dude and he thought the problem might be that stored for that long of a time, water may have built up in the tank. In any case, I also bought some of that CRC guaranteed to pass and followed the directions [Put it in the tank, burn the tank down, and put new good quality gas in]. So I refilled with 92 Octane, and went back in for the emissions test.

The HC tests were both similar, but the new IDLE CO was reduced 200x.

Cruise Limit CO(%) 0.09[1.1] PASS
Idle Limit CO(%) 0.01 (1.2) PASS

What a difference a new tank of gas made!

Thanks again for your help kchungb17a, I very much appreciate it.

 

Awesome, congrats!