CO Emissions value

[a5gcd]

Can anyone tell me what the preferred value is for CO emissions.

The MOT is looking for a max of 3.5. I have just had my 91 Se turbo done and got a figure of 0.172!!

I am running with an Everest chip and a drop in K&N filter but all else is standard.

Will a figure this low cause any prolems? The only problem I have noticed is a slightly lumpy tickover.

Geoff

[johnbenk]

Hi

This sounds like the Co Potentiometer neeeds adjusting and also what reading are you getting on RPM at tickover on warm engine.

Have you got any access to the EMPFI (openloop) Service notes which details this proceedure.

Rough,unstable,or incorrect idle is covered in this section or anybody living near you has Elanscan to run a diagnosis on the engine.

Cheers,

Jbenk.

[John_W]

Geoff,
If you have replaced your old chip (assuming it was the original "9239" chip) with a Mountain chip (based on the latest "9930" Lotus chip) without re-trimming the CO pot, the idle mix willl be wrong, giving lumpy idle and too low CO emission.

The solution is to re-trim the pot which is easy.

See
here (Posted: 24 Apr 2005 09:24) and here about half-way down (Posted: 15 Aug 2004 16:49).

John

[theelanman]

go on then...in one easy lesson what do you do with your co2 pot to adjust it???....
I think mine was played with by the dpo and now that its getting 'regular' use its running a bit 'off'.......
story was the co2 was way over on the mot but after 'tinkering' passed..I reckon they just p!$$ed about with the co2 pot until it passed...
I'm fitting alans chip and want to know how to play with this bit to sort it all out once and for all..
cheers
G

[Avonvilla]

What should the value be at ?

[Monty]

Just dug out the emissions test when Pinky II went for an MOT,

CO limit 3.5%, mine was 1.71%

HC limit 1200 ppm vol, mine was 127 ppm vol

Whats the HC test thingy-me-jig?

Geoff,
Yours is really low, sounds like u need to take John.w`s advice and adjust the CO pot

[rob]

My last MOT reading was 0.19 and I think the limit is 0.2 for my car (1995) and that is with the the main CAT removed but the pre-CAT still in situe. No Co2 to adjust either, just go and give it a good thrashing before you take it to the test centre.

[John_W]

CO limit 3.5%, mine was 1.71%
HC limit 1200 ppm vol, mine was 127 ppm vol
Whats the HC test thingy-me-jig?

Monty,
HC should be the amount of unburnt hydrocarbons in the exhaust (for Stevo's benefit I don't know it that's before or after afterburners).

My last MOT in April (SE) had :
CO level at idle: 1.47% volume (acceptable limit 3.5%)
Hydrocarbons: 83 ppm (acceptable limit 1200 ppm).

Elanman,
follow the links in my previous post for instructions on adjustment.

Avonvilla,
Monty quotes the correct values for the SE (if you've got the CO pot then you've got a SE and you don't have to comply with the values Rob quotes for a S2 with cat). There is no unique relationship between resistivity values from the pot and exhaust emissions values; it depends on your state of tune. With the car properly set up (timing, plugs, fuel, warmed up, etc) you have to measure the emissions and trim the pot accordingly, or do it by ear (which I've found to be fine).

John

John

[a5gcd]

Geoff,
If you have replaced your old chip (assuming it was the original "9239" chip) with a Mountain chip (based on the latest "9930" Lotus chip) without re-trimming the CO pot, the idle mix willl be wrong, giving lumpy idle and too low CO emission.

The solution is to re-trim the pot which is easy.

See
here (Posted: 24 Apr 2005 09:24) and here about half-way down (Posted: 15 Aug 2004 16:49).

John

Thanks John

This is exactly my situation, I will try to find a friendly garage man with a emissions tester so that I can adjust the CO pot to get the recommended 1% +/-0.5% as quoted in the service manual.

Geoff

[Avonvilla]

CO limit 3.5%, mine was 1.71%
HC limit 1200 ppm vol, mine was 127 ppm vol
Whats the HC test thingy-me-jig?

Monty,
HC should be the amount of unburnt hydrocarbons in the exhaust (for Stevo's benefit I don't know it that's before or after afterburners).

My last MOT in April (SE) had :
CO level at idle: 1.47% volume (acceptable limit 3.5%)
Hydrocarbons: 83 ppm (acceptable limit 1200 ppm).

Elanman,
follow the links in my previous post for instructions on adjustment.

Avonvilla,
Monty quotes the correct values for the SE (if you've got the CO pot then you've got a SE and you don't have to comply with the values Rob quotes for a S2 with cat). There is no unique relationship between resistivity values from the pot and exhaust emissions values; it depends on your state of tune. With the car properly set up (timing, plugs, fuel, warmed up, etc) you have to measure the emissions and trim the pot accordingly, or do it by ear (which I've found to be fine).

John

John

I have an S2 with a large loss of power although all drives well and having changed lots of things previously i am wondering now if it could be the O2 sensor and wether the values obtained in an emissions test would help point to this or not, looking like not i guess ?

Thanks

[John_W]

Avonvilla,

Ah, an S2... CO pot discussion not much use then. I'm afraid I know nothing about O2 sensors. I'm sure you'll have checked these, but the first places I'd look for power loss on an S2 are incorrect static timing or blocked pre-cat or main cat giving restrictions in the exhaust.

John

[Avonvilla]

John_W

No pot for me but still unsure if it could be the sensor or not.

Done all the usuals like timing, plugs etc and i currently have no cats at all and that was the best it's been but still 30-40bhp short. Annoying thing is it all drives fine but just not quick enough

Thanks