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MOT Emission level for UK Subaru-Any MOT testers about?

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Old Apr 27, 2007 | 11:01 AM
  #1  
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Steve Whitehorn
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Question MOT Emission level for UK Subaru-Any MOT testers about?

Hi
I need to know what at what level of emmision is permited to pass the MOT.

(The stuff below is from the MOT website but doesn“t give a fail percentage)

If a vehicle has a dual exhaust system, then the emissions from the tailpipes should be averaged. This is done by adding together the readings and dividing by two, eg

CARBON MONOXIDE
1st pipe emits 6% CO, 400 ppm HC
2nd pipe emits 4% CO, 500 ppm HC
Average CO reading is
6+4/2=5%

HYDROCARBONS
Average HC reading is
400+500/2=450ppm

So.....
1. Is it just Carbon Monoxide and Hydrocarbons that are measured during the MOT
2. Are they always measured in % for Carbon Monoxide? And what is the fail percentage?
3. Hydrocarbons are these allways measured in ppm? And what is the fail figure?
4. What is ppm short for?
5. Is there a test for noise level during the MOT?

The car would be a facelift late UK classic.
Alternatively has anyone got a MOT sheets that list the perameters of pas and fail - for this and anything else that is usefull.
This info would really help me out - so replies much appreciated
Thanks
Steve
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Old Apr 27, 2007 | 02:43 PM
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just had mine done an hour ago
fast idle speed co: max 0.200%
hc: max 200 ppm
lamba: 0.970-1.030

natural idle co: max0.300%

oh and ppm is parts per million
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Old Apr 27, 2007 | 02:52 PM
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Thanks
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Old Apr 27, 2007 | 05:48 PM
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If this is any help, If your car fails the emmisions by a small amount and the testing station will let you turn on all the car electrics, lights rear window heater,fan etc, this pulls power from the ecu and makes the makes the managment of the engine less precise!, try it!
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Old Apr 27, 2007 | 06:43 PM
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From: Old Codgers Home
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Originally Posted by suffolkdar
If this is any help, If your car fails the emmisions by a small amount and the testing station will let you turn on all the car electrics, lights rear window heater,fan etc, this pulls power from the ecu and makes the makes the managment of the engine less precise!, try it!
FPMSL

Absolutely BRILLIANT!!

Pulls power from the ECU Not from the Battery then?

I am in tears here - funniest thing I have heard in years

CLASSIC!!
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Old Apr 27, 2007 | 08:46 PM
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think it's just the load on the engine that makes the emissions slightly different
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Old Apr 27, 2007 | 11:31 PM
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Many engine management systems implement part of the idle stabilisation algorithm by advancing the ignition timing when load is increased. So increasing the load on an idling engine causes the timing to be advanced slightly and this can slightly reduce the emissions.
Not sure if this is how Subaru do it - but its quite likely.
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