Bringing CO emissions down

[soldave]

One of my MOT failures this year was CO emissions, which I've not had before. Whilst 4.5% is permitted, I had a value of 5.51%. A little strange as nothing's really been done on that side apart from a tune last summer, but that's besides the point. The main thing is that I need to bring down CO levels by 1% and I'm not sure how best to do it. Is it a case of pulling out the Colourtune and making sure everything looks good in terms of spark colour in the cylinders, or is there a better method?

Any advice on this would be greatly appreciated.

(The other failure was a rotten rear radius arm; in my eyes more serious but hopefully once off the car it can be welded and sorted out without too many issues).

[Alan_M]

Did you give the car a good run before being tested? Have you pulled out plugs to see what colour they are, and gapped correctly and in good condition? What was the HC value?

Before adjusting carbs make sure the ignition system is working at it’s best so you have a good spark being delivered at the correct time.
As to the best way to adjust - have you got, or can you get access to a CO meter? Where abouts are you located? If you’re around S Wales, Wiltshire or Birmingham I have a CO meter ( I live in S Wales, but regularly travel to Swindon and Birmingham.

[soldave]

Car was up to temperature, but not a good drive beforehand. HC value was 329 so well within the 1200ppm requirement. I will check the ignition system though.

Based in West Yorkshire but I do appreciate the offer of the CO tester

[amarshall]

We should have a suitable meter for the club, soon. It'll be based in Darlington, so not far away.

[jeff.fenton]

Hello Dave, I'm about 5 miles from Wakefield, (Batley), and have a co meter you can borrow. I tried to Email you my details, but can't seem to get it through. Can you Email me your phone number? Jeff.

[soldave]

Hello Dave, I'm about 5 miles from Wakefield, (Batley), and have a co meter you can borrow. I tried to Email you my details, but can't seem to get it through. Can you Email me your phone number? Jeff.

Just spotted this. Email sent

[RED BARON]

I asked if I could borrow that CO meter from another member and even offered money as he was willing to lend to the other member for free but was turned down, so went and bought a new one.

I set it up as per instructions and got a CO reading of 2.35%. I did have new plugs and air filter fitted as it
hadn't been out since complete service including timing belt.

I was going to buy a cab setting gauge set as they are only about £56 but as the car has only done 53K
which is quite low for a 1990 car and it did seem to run sweet, thought they should be ok as the paperwork I got with the car showed it had been well maintained.

Anyway it went for the MOT Friday and passed at 1.61% CO and 556 HC which was lower than my reading
so I was glad I bought the analyser which gave me peace of mind.
They gave me a complete readout of the figures and was surprised when I asked for it as they said you automatically get it as part of the MOT.

O yes and before it went had 4 new tyres fitted even though they were ok lots of tread no cracks they were dated 2009 so a bit old.

Also while it was at the MOT station I had the tracking Laser set and they gave me a complete readout of the set up. I had this done as it hadn't been set since I replaced the springs, dampers, brakes ect. On the way home gave it a good burst of speed as it was now only the second time I had driven it since I got it back in May last year, and wanted to see what she would do.

Finally I still have a few thing I want to do like new door seals, replace the font under bumper skirt and I would like to fit a third high level rear brake light but am unsure as I do like to keep cars as they left the factory.


Ian.

[AndyC]

Soldave.
One of mine ha just ad it's MOT, and was around 0.25 / 0.30 of the permitted limits for both C and Hydrocarbons, so should be easily achieved. Since your Hydrocarbons doesn't appear elevated but CO is, I doubt that it's ignition causing a poor burn, as I'd expect bot to go up if it were failing to ignite well. I'd guess you can enrich the mixture on one or more cylinders and get a much better CO reading without massively increasing the Hydrocarbons level.

A few years back, one of mine failed due to a poor rotor arm shorting out under load. I managed to get get it to pass, then sorted the rotor arm and ad to re-adjust to get mixtures back to a more-normal situation. So, even if it's not what you want to run with, as long as it passes the MOT you can do a temporary setting.

[soldave]

Soldave.
One of mine ha just ad it's MOT, and was around 0.25 / 0.30 of the permitted limits for both C and Hydrocarbons, so should be easily achieved. Since your Hydrocarbons doesn't appear elevated but CO is, I doubt that it's ignition causing a poor burn, as I'd expect bot to go up if it were failing to ignite well. I'd guess you can enrich the mixture on one or more cylinders and get a much better CO reading without massively increasing the Hydrocarbons level.

I might be completely wrong here, but wouldn't making the mixture richer increase the CO even further? My thought when removing the air filter was to increase the airflow into the carbs to bring the mixture a little leaner.

[AndyC]

Sorry, yes I meant weaken not enrich (although if the mixture is way too weak you can get an incomplete burn, leading to excessive CO and HCs so in tat extreme enriching would help). Air filter shouldn't really effect things, as the fuel is picked up by the passing air, so more air = more fuel much the same as raising the idle stop setting a minute amount would (although it may vary by using different jets).

[soldave]

Well, many thanks to jeff.fenton I have been able to do some exhaust emissions testing after work today. According to the meter I started at 5.6% CO which is pretty close to what the MOT centre had. Went through the carb balancing process and once done tested again. 3% was the final figure which I'm pretty happy with. We'll find out on Saturday what the official figures say but, touch wood, I should be in a good place.

[soldave]

Success! Re-did MOT today and got CO emissions of 2.68% and HC of 685ppm which is much better, and also within the Lotus factory specs for CO emissions. All good and problem solved

[Hawaiis0]

Success! Re-did MOT today and got CO emissions of 2.68% and HC of 685ppm which is much better, and also within the Lotus factory specs for CO emissions. All good and problem solved

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