What are ways to lower the CO in a Honda Civic?

 

^Not enough information. Post the smog sheet and give some background.

 

Test: HC CO% NO
15 mph 6 0.98 153

25MPH 7 0.10 310


I failed on the 15 MPH part of the test. No engine light, replaced spark plugs and distributor cap, changed oil and coolant.

 

What are the max allowable levels for each pollutant?

 

Did you get a timing light and verify timing is within spec?

 

At 15MPH: HC 66 CO .57 NO 487
25MPH: 49 .55 774

 

Any thoughts or ideas?

 

I'm stumped. I would have expected the high CO to be accompanied by high HC, but it is not. Only CO is high. The only thing I could think to do is change the air filter.

Does the sheet have any other information on it? Can you post it?

 

Give us a photo of the smog sheet so we can diagnose this further.

Check or replace PCV valve, along with the filter as stated above ,does your engine leak oil from anywhere?

I feel your pain Ron, kinda lost on this one, we really need the sheet.

 

i had the same problem as OP. i replace cap/rotor, spark plug/wires, new o2 sensors & new cat. it failed with high CO level. Tech said it was a bad cat but the cat i replace was in good working condition & came off of an '00 SI.

unfortunately i forgot & left the smog sheet at the station. But from what i "heard" i have to run the car SUPER hot to heat up the cat for it to be in working condition since the cat hasnt been used for more then 6 months.

 

i had the same problem.. come to find out my catalytic converter had 150k miles on it. it had blown out all the packing inside (the packing inside heats to extreme temps and burns the excess CO produced by your engine) once replaced i passed with flying colors. another "ghetto" easy way of getting threw would be to pull an injector clip,car will run like crap but it pumps straight oxygen threw the systems in turn lowering CO

 

i have replaced the cap/rotor, spark plug/wires, air filter. there is some small oil leakage here and there. after i replaced there was increase in CO measurement.

unable to post pic until I am no longer on trial user status

 

What gives you this^ false impression? Post the sheet.

 

unable to add any attachments or photos

 

You are able to post pictures. Describe what you are doing.

If you look carefully, you'll find that the stickies at the top describe two different ways to post pictures.

 

Please read the stickies (gray highlighted threads) so that you can learn the proper way to post pictures.

Methods:

1) Photobucket

2) Honda-tech Attachments feature.

 

 

It seems like the engine is getting less air that it requires, leading to increased CO production.

You might want to replace the PCV valve.

How's the idle speed?

 

its idles under 1000rpm. if that's what u mean by idle speed

 

pull 1-2 deg timing,
increase idle 50-100rpm.

 

turned out to be cracked exhaust manifold...and bad O2 sensor

 

This^ is hard to reconcile when you consider the posted emissions data. For example, a cracked manifold would be expected to raise O2 levels in the exhaust, yet O2 levels remained at undetectable levels at both 15 and 25 mph.

And it's still hard to understand how a bad O2 sensor would only raise CO levels without also raising HC levels.

My guess is that either the machine used to measure the emissions gases malfunctioned that day of the test or there was operator error.

 

This is extremely possibe