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Sean
Firing on two.
Joined: April 22nd, 2009, 11:06 pm
Posts: 3684
Location: Ecosse
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 Re: EXHAUST EMISSIONS ken wrote: Citroen's 'target' setting for CO emissions at idle is between 0.8% & 1.6%. Too low and the idle is uneven, too high and there's that pong of unburnt petrol from the exhaust.  Sean wrote: yes its a bit lean it may hesitate coming off idle
aircooled engines need to be set richer than the ideal but the emissions is so generous that if you were at the top end youd be stinking of petrol edited so other people know what i meant as well as me 
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Kissing the Lash
"Any advice of a technical nature is given on the understanding that I've actually done this shit, not just read about it in D*lly club mag some time ago.
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| April 1st, 2014, 10:10 pm |
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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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Re: EXHAUST EMISSIONS ken wrote: "NOx = Oxides of Nitrogen (This is only seen by a 5-gas analyser) Only seen with dynamometer or engine under load. NOx emissions rise and fall in a reverse pattern to HC emissions. As the mixture becomes leaner more of the HC's are burnt, but at high temperatures and pressures (under load) in the combustion chamber there will be excess O2 molecules which combine with the nitrogen to create NOx" Nelsthebass wrote: Had two tests on Celeste and they were 238 and 302 - is the HC test one of making sure engine is burning fuel completely and therefore not emitting much NOX? I knew it had something to do with that but obviously the wrong way round.....
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1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| April 1st, 2014, 10:22 pm |
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Jonathan
Firing on two.
Joined: January 1st, 2009, 7:37 pm
Posts: 4708
Location: Disunited Kingdom
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Re: EXHAUST EMISSIONS So can I leave things well alone or should I alter something? 
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1988 built (1989 F-registered) Citroën 2CV-Six
2013 (63-Plate) VW Golf SE 1.4TSI BMT DSG7
1932 Morris Minor Open Two-Seater (The £100 car).
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| April 1st, 2014, 11:08 pm |
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ken
Agony Aunt - You have a car problem? Speak to Ken
Joined: March 6th, 2009, 1:40 am
Posts: 3675
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Re: EXHAUST EMISSIONS Richen the idle mixture a bit, by turning the adjusting screw anti-clockwise about 1 (or 2) turns. It's the one which sits at an angle on the front face of the carburettor. Afterwards, you should be able to lower the idle speed, which I'd suspect is set high to cope with the overly weak idle mixture. Jonathan wrote: So can I leave things well alone or should I alter something?
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| April 1st, 2014, 11:49 pm |
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ken
Agony Aunt - You have a car problem? Speak to Ken
Joined: March 6th, 2009, 1:40 am
Posts: 3675
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Re: EXHAUST EMISSIONS Nels, source of that quote is here. http://www.crypton.co.za/Tto%20know/Emi ... sions.htmlNelsthebass wrote: ken wrote: "NOx = Oxides of Nitrogen (This is only seen by a 5-gas analyser) Only seen with dynamometer or engine under load. NOx emissions rise and fall in a reverse pattern to HC emissions. As the mixture becomes leaner more of the HC's are burnt, but at high temperatures and pressures (under load) in the combustion chamber there will be excess O2 molecules which combine with the nitrogen to create NOx" Nelsthebass wrote: Had two tests on Celeste and they were 238 and 302 - is the HC test one of making sure engine is burning fuel completely and therefore not emitting much NOX? I knew it had something to do with that but obviously the wrong way round.....
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| April 1st, 2014, 11:55 pm |
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Jonathan
Firing on two.
Joined: January 1st, 2009, 7:37 pm
Posts: 4708
Location: Disunited Kingdom
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Re: EXHAUST EMISSIONS ken wrote: Richen the idle mixture a bit, by turning the adjusting screw anti-clockwise about 1 (or 2) turns. It's the one which sits at an angle on the front face of the carburettor. Afterwards, you should be able to lower the idle speed, which I'd suspect is set high to cope with the overly weak idle mixture. Jonathan wrote: So can I leave things well alone or should I alter something? Thank You. 
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1988 built (1989 F-registered) Citroën 2CV-Six
2013 (63-Plate) VW Golf SE 1.4TSI BMT DSG7
1932 Morris Minor Open Two-Seater (The £100 car).
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| April 2nd, 2014, 12:23 am |
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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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Re: EXHAUST EMISSIONS Ken - interestingly, looking at the graph on the link, low HC is likely to give both lower NOX and, at the lower end, rich mixture - or am I reading it wrong? Granted, on a running car, only a gas analyser will tell which side of ideal you would be using HC alone.....
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1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| April 2nd, 2014, 9:29 pm |
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ken
Agony Aunt - You have a car problem? Speak to Ken
Joined: March 6th, 2009, 1:40 am
Posts: 3675
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Re: EXHAUST EMISSIONS Nels, not sure if you've registered that NOx is only created at 'high temperatures and pressures', so is not a factor which needs to be taken into account at tickover, more of a reason never to choose a picnic spot by the side of a motorway.  The primary variable in that graph is the air/fuel ratio, btw, so everything else depends on it. Anyhow, I thought you'd be more interested to note that peak power is obtained when the air/fuel ratio is slightly rich of stoichiometric, another reason for re-jetting even if it wasn't already required to cater for ethanol and other additives in unleaded. ken Nelsthebass wrote: Ken - interestingly, looking at the graph on the link, low HC is likely to give both lower NOX and, at the lower end, rich mixture - or am I reading it wrong? Granted, on a running car, only a gas analyser will tell which side of ideal you would be using HC alone.....
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| April 2nd, 2014, 10:09 pm |
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Nelsthebass
Firing on two.
Joined: October 5th, 2009, 8:22 pm
Posts: 1415
Location: Stone, Staffs
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Re: EXHAUST EMISSIONS I was really meaning in an ideal world, not home tinkering at tickover - I certainly will look at enriching the primary jet on the Celeste - plugs are very pale around the tip which I believe indicates lean running?
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1987 2CV Special
2014 Suzuki Swift Sport
2015 Lexus NX300h
1966 Ami Break
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| April 2nd, 2014, 10:26 pm |
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Jonathan
Firing on two.
Joined: January 1st, 2009, 7:37 pm
Posts: 4708
Location: Disunited Kingdom
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Re: EXHAUST EMISSIONS Finally got round to adjusting that idle mixture screw about twenty minutes ago. Took it for a good run to get the engine nice and hot, and I can't believe the difference. Wow! I've only turned it half of one turn so far and it now picks up pace without hesitating as it did before. I might leave it well alone now as it hasn't appeared to have altered the idle speed, which is a bonus.
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1988 built (1989 F-registered) Citroën 2CV-Six
2013 (63-Plate) VW Golf SE 1.4TSI BMT DSG7
1932 Morris Minor Open Two-Seater (The £100 car).
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| April 16th, 2014, 3:50 pm |
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