Having just had a MOT, the results from the Emissions Test make no sense to me, except that the car passed (mercedes A140)
Are all the test results OK (i.e running at optimum, rather than just enough to pass)
Can someone have a quick look at the test result, and let me know!!
cheers
BET Test Result: Catalyst vehicle with closed loop control
Fast Idle Test
CO = 0.00
HC = 00010
LAMBDA = 1.00
Natural Idle Test
CO = 0.00
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What on earth is this thing running on? Those results look P.D.I! The lambda should be 1 under ideal circumstances, and the CO level should be as low as possible, but 0 seems unfeasibly low to me. Not sure what a typical hydrocarbon level is, but that seems good also.
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Just regular Shell unleaded, and Mobil 1 synthetic oil.
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HC levels are apparently based on the manufacturer's specifications, but somewhere in the region of 200 would probably be a fail for a car like this. (A non-catalysed car would fail on 1200). Basically, the car passed with colours that were not merely flying but in orbit.
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I'm sure most test certs have this on, but from the one for my Yaris:
The fast idle test is performed between 2500 and 3000 RPM. (Although oddly enough this is shown as not being checked for mine)
Carbon Monoxide levels must be less then 0.3% by volume. (Mine was 0.01%)
Hydrocarbon levels must be less than 200 parts per million. (Mine was 4)
The Lambda reading must be between 0.97 and 1.03. (Mine was 1.012)
I don't know the full technical details, but the Lambda reading is a sort of 'balancing' figure. The ECU will adjust the mixture of the engine continually to get a reading of 1. I'm sure someone can tell me the technical details as to just what this relates to. (Something to do with oxygen levels in the emissions)
So, with the exception of the Lambda reading, my Yaris passed with flying colours. Not sure if the slight deviation in Lambda is anything to be worried about, although as the car is only 3 years old and had done about 1000 motorway miles in the 2 or 3 weeks before the test, I'm surprised it's not bob on.
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Lambda is indeed a ratio, and you can't actually measure it - you can only infer it from other measurements. At lambda = 1 the ratio of air to fuel is the correct 14.7:1, this gives minimal CO and helps to limit NOx - higher ratios mean leaner combustion which is hotter and produces more NOx, lower ratios mean rich combustion which produces CO due to insufficient oxygen. The 'lambda' sensor is actually an oxygen sensor, and really only has 2 states - oxygen or not. So, when the engine is running if it detects oxygen the ECU richens the mixture up till it sees no oxygen when the ECU leans the mixture back again, ad infitum - this is why you need an oscilliscope to test the sensor as its voltage goes up and down all the time.
Richard
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Last Friday, 4 year old Scenic 1.6, 45,000 miles
Fast Idle Speed 2800rpm
CO: 0.00%
HC: 0001ppm
Lambda 1.003
Natural idle speed 734rpm
CO: 0.00%
On Tesco's Finest supermarket brew
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Hi
how on earth did you lot get such low readings
J Stephenson
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Simple.These cars are obviously well maintained, get regular good runs (ie. other than crawling around town all day), and their engine management systems are working 100%, especially with regard to the Oxygen Sensor and Catalytic Converter
operation.
Regards, Adam
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Hi how on earth did you lot get such low readings J Stephenson
Nothing special, has been serviced on schedule. It gets an Italian tune up once a week. When its nice and hot, it gets taken up to the rev limiter thro three gears. Gets one long motorway run (200 miles return) month.
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James, don't forget that modern cars are catalysed and comply with Euro 3/4 standards. Our cars don't have cats and even if they did they would be significantly less sophisticated. A well maintained, well driven, low mileage modern car will have emissions figures (except CO2) that will blow away anything even ten years old, which will be massively better than a 15-year-old.
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James, don't forget that modern cars are catalysed and comply with Euro 3/4 standards. Our cars don't have cats and even if they did they would be significantly less sophisticated. A well maintained, well driven, low mileage modern car will have emissions figures (except CO2) that will blow away anything even ten years old, which will be massively better than a 15-year-old.
Not entirely true. I was very surprised recently when I got a 1986 Volvo 240 with a Cisak carburettor, no catalyst, through the emissions test with readings that would have been spot on the limits for a catalysed car.
I don't know what is special about this car - I agree that older ones are much worse, by a factor of 10 at least.
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Last Aug, 96P Rover 820 turbo at 117,400 hard driven miles:
Fast Idle Speed 2813rpm
CO: 0.01%
HC: 0004ppm
Lambda 1.004
Natural idle speed 826rpm
CO: 0.00%
On Tesco's bog-standard supermarket brew (rarely buy anything else), Castrol RS in the sump (usually it's Halfords Fully Synth) and 1000 miles before a full 24k service.
Also, brake balance was under 5% on both axles (8% on the handbrake though).
Shows the value of a high standard of maintenance IMO.
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Missus nine year old Pug 306 1.8 8v.
"14K and a bit" miles in eight years with previous owners, then 5k miles in 7 months with the missus, either three miles to work across town, or 20 miles to alternative work in another town.
Beyond a clutch cable and cambelt, has not been touched since we purchased it, though it will be serviced next weekend. Missus drives it too gently (in 5th gear by 30 mph every time), and I therefore give it an Italian Tune Up whenever I get opportunity, including for ten miles DIRECTLY before the test last week.
Fast idle speed 2865 rpm
CO = 0.00% (Fail = .30%)
HC = 0 ppm (Fail = 200 ppm)
Lamda = 1.01 (Min allowed .97 Max allowed 1.03)
Natural idle 837 rpm
CO = 0% (Fail = .50%)
Not too bad for a nine year old cheap and cheerful motor, with a prehistoric basic engine design (XU7), methinks.
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But with a 1983 metro you pass with 4.5% CO limit and no HC limit.
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Yes but it then fails due to rust
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