Sure is. My neighbour is off to France on Friday for a month with the caravan. I've told him he's not allowed to take our weather with him! ----- Original Message ----- From: Owen Jenkins To: mogtalk2 Sent: Wednesday, May 23, 2012 8:49 AM Subject: Re: [mogtalk2] Sweating at the MOT
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
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