Dave, Thanks for this. More mysteries of the universe revealed. Glorious here in Aboyne today. 22°C yesterday, -4°C last Saturday night. Straight from winter into summer.
Cheers, Owen. ----- Original Message ----- From: Dave Wellings To: mogtalk2 Sent: Tuesday, May 22, 2012 8:29 PM Subject: [mogtalk2] Sweating at the MOT Some of you will no doubt know all about this, but here is my story from yesterday, just posted on Talkmorgan. MOT today. The form has now been dumbed down. Instead of the green hard to forge certificate, it's a simple white page print out, with any advisories on the right hand side. What's more interesting, and worrying is the Lambda requirement. This measures the fuel/air ratio at the tailpipe, and is between two parameters, which for my Morgan is (allegedly) 0.9 to 1.03. This is a very narrow band. On the screen, this displays as a red band with a narrow green pass band. The measure is shown as a white bar, and is taken at a prescribed 'fast idle' - just under 3000rpm. It was a struggle to get below 1.03. After a couple of attempts the tester managed 1.025. A high reading indicates a leak in the exhaust system, but both tailpipes produced the same effect. There is no obvious leak, but the Lambda shows a weak mixture. On checking last years result, it was 1.024, so that was right at the top end. The machine can't be conned, so exceed the limit and you will fail. The science: Lambda is a measure for the mass air to fuel ratio present during combustion. When exactly enough fuel is combined with the available free oxygen, the mixture is chemically balanced and is called stoichiometric. Lambda = 1 -stoichiometric mixture Lambda < 1 -mixture is rich, excess fuel present Lambda > 1 -mixture is lean, excess air present The amount of air that is needed depends on the type of fuel used. In the case of petrol, a stoichiometric mixture consists of an air/fuel ratio of 14.7/1. Peak power is at Lambda 0.84 to 0.90 Optimum economy at Lambda = 1.05 Optimum emissions at Lambda slightly below 1.0 Thinks..I wonder if the ECU is set for 'economy'..... .................................................... More news. I was concerned enough to look further into this. The emission data is published each year by VOSA and is here: http://www.dft.gov.uk/vosa/repository/Emissions%2017th%20Edition.pdf This is the "In service emission standards for road vehicles" - seventeenth edition. Published in February 2012 and available on the link above. ISBN 978-0-9549352-7-6 Morgan is on pages 97 and 98......... The data shown covers the following: Normal idle: Max CO limit (%)vol: All models 0.5 Normal idle speed Min Limit and Max Limit RPM. Varies as follows: 4/4 1.6EFI CVH 750-850 4/4 1.8EFI MVH 850-950 Roadster 3.0V6EFI 750-900 Plus 4 2.0 T16 850-950 Plus 8 3.5 750-850 Plus 8 3.9 750-900 Plus 8 4.6 750-900 Plus 8 4.0 750-900 4/4 2.0 Duratec 700-900 4/4 1600 Sigma 650-1000 Aero 8, 4.8 Manual/Auto, Max and SS 650-1000 Fast idle Max CO limit(%vol) 0.3 all models. Max HC limit all models: 200 Minimum Lambda: All models 0.9, EXCEPT Plus 8 4.0 and ALL Aero's which are 0.8. Maximum Lambda: All models 1.05. (NOTE, this means that my 1.025 is well within parameters). Minimum RPM - Fast Max limit RPM 4/4 1.6EFI CVH 2800-3100 4/4 1.8EFI MVH 2800-3100 Roadster 3.0V6EFI 2750-3000 Plus 4 2.0 T16 2500-3000 Plus 8 3.5 2500-3000 Plus 8 3.9 2500-3000 Plus 8 4.6 2500-3000 Plus 8 4.0 2500-3000 4/4 2.0 Duratec 2750-3000 4/4 1600 Sigma 2500-3000 Aero 8, 4.8 Manual/Auto, Max and SS 2500-3000. So if you have any Lambda troubles on test, refer the tester to this tome. By the way, my MOT man is very good, and well used to my odd cars, but was obviously unaware of the upper Lambda limit for Morgans. Dave View posts on The Mail Archive http://www.mail-archive.com/[email protected]/ Modify Your Subscription ------------------------------------------- View posts on The Mail Archive http://www.mail-archive.com/[email protected]/ [http://www.mail-archive.com/[email protected]/] Modify Your Subscription: https://www.listbox.com/member/?member_id=22459785&id_secret=22459785-4a39ddf8 Powered by Listbox: http://www.listbox.com
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