CO level (Carbon monoxide)

[kayw]

Hi,

I am living in Hong Kong that the Goverment requires to have emission test annually. The max CO level is 3.5%.

My car passes with a record 2.4%. The service manual indicates that the normal level is 0.5-1.5%. The car is old, I know, but which parts should I work/repair/replace in order to decrease the CO level??

My car -- 944S2, 3.0L NA, 1989

Thanks!!

Kay

[flangermog]

You can adjust the mixture quite easily on an S2 with a hex bolt.
As you open the hood(bonnet) just to the right of the middle of the car is an aluminium box with squares on it. if you reach underneath on the left hand side and towars the back you will feel the hex bolt there -this controls how rich the engine is running and you can tweak it.

The guy who did my emissions test just tweaked mine for me because it failed first time. All sorts of things can affect the CO levels, but this is the simplest to adjust.

If you're still high you might be burning oil or something...

Don't forget though these cars are old now and it may not be possible to get as low as 0.5 - 1.5%

[kayw]

Hi, Thanks for quick reply. I attach a photo of my car. Do you mean the thing marked by red? It is the air flow meter, I guess. However, when you go to adjust, how do you know the adjustment is proper?? Did you do it at the auto shop with somebody connected a sensor to the muffler?? 2.4% is still a pass grade. I just worry the CO goes higher when the car is older. It is 16 years old!! At least, it is too late and too rush to seek a solution when it reaches 3% (3.5% is the max level) I don't see any oil burn. Does oxyen sensor relate to CO level too?? If so, could it be cleared (like clearning a spark plug?) Thanks! Kay

[boxsterpontus]

Why is the airflowmeter mounted uside down on the later cars. It looks really strange.

[Makis]

Originally posted by kayw
Does oxyen sensor relate to CO level too?? If so, could it be cleared (like clearning a spark plug?)

If you have oxygen sensor (O2) you cannot really adjust the C0 from the AFM. The O2 will adjust it for you. A old O2 sensor together with an ineffective CAT will increas CO levels. Don't think you can clean O2 sensor but you can replace it with an universal 3 wire sensor. Do this first before trying other modes.

[TCMdocs944]

I would replace the O2 sensors as a first.

BUT


I am pretty sure you CAN adjust the CO levels. Just isn't commonly done. The only way to test is when hooked up to a shop emissions machine.


Kay!! Do not worry, you passed!

[kayw]

Yes, I know I pass, but worry fail next year (or 2 years later)

If I have chance to go to an auto shop, I will try adjust the AFM. O2 sensor should be easy to replace by myself (is the one located at the outgoing air pipe?)

Just some info to share... a new emission requirement came up in 2001 in Hong Kong that CO level of car produced after 1991 couldn't exceed 0.5%... lucky my car is 1989 otherwise it would be a big problem....

Thanks all for help!

Kay

[SoCal Driver]

The air bypass on any AFS (air flow sensor) is effictive only at an idle. Once the baffel moves the air bypass is moot.

As to CO emissions testing; Kyoto is BS!

[kayw]

"As to CO emissions testing; Kyoto is BS!"

what does it mean??

Kay

[SoCal Driver]

The reason you are being tested for CO is the Kyoto treaty where signing countries agree to monitor and reduce CO emissions. There is some absent minded connection being contrived with the recent historical fluctuations with average global temps and the minor increase in recent CO.

So you get tested for just the CO and not the other emissions your car is discharging. There is a balance point between the three main emissions that an engine runs the best at. Testing for just one is foolish.

[flangermog]

I agree SoCal, I think more harm than good will come from singling out the CO emissions as people will concentrate on lowering their CO possibly at the expense of other gases, causing cars to run very poorly and in the case of older cars like ours this could result in long term damage from continued use with the poor set up we are being forced into using just to stay on the road!

The UK signed up for the agreement and set out to reduce their pollution levels by 2012 i think. They have since risen consistently each year, whereas before signing the treaty they were pretty consistent! Interesting...

[SoCal Driver]

National Geographic has a panic laced article on global warming. Problem is one of their graphs shows that the recent ten to twenty thousand years is one of a cycle of 100,000 year warming and cooling periods for the earth. The temps from the last few thousand years is a poor example to use. Our last six to seven thousands years on this planet is just a blink of an eye in geological time.

I would want an engine to run as efficiently as possible to conserve fuel. This means high temps in the engine and high levels of NOx. Also CO as you get CO from burning most anything.

[bryanthompson]

I heard a story on NPR of all places about plants that grew waaay quicker in swamps & things when higher levels of CO were introduced.

Me: Help the plants grow, put more CO in the system!