Mot emissions test
Discussion
Having absolutely no luck with my cars today two of them seem to be falling to pices my passats bonnet keeps coming of its first catch and now my sapphire has failed its mot.Right just got a hold of my mot fail sheet and it has failed on exhaust emissions on the carbon monoxide on both fast idles and the natural idle and i see by the sheet it has been tested as a catalyst vehicle but i didnt think it had a catalyst fitted,its a 1992 sapphire glsi registered 18th august 1992 but looking at an mot testers manual all cars used after 1st august 1992 are tested as catalyst.The readings are
fast idle co limit 0.300 co actual 2.105
second fast idle co limit 0.300 co actual 2.394
natural idle co limit 0.500 co actual 3.896
Can anyone advise.Thanks
fast idle co limit 0.300 co actual 2.105
second fast idle co limit 0.300 co actual 2.394
natural idle co limit 0.500 co actual 3.896
Can anyone advise.Thanks
I use to be a tester up until a few years ago and cat tests were vehicle specific up until about 1995. AFAIK a sierra should never qualify for a cat test. Lots of cars pre 1995 were still on carbs and had no chance of passing cat tests. Im pretty sure a 1992 should not be subject to a cat test.
Found this info :
EMISSIONS FAILURE
My car has just failed theMOT Test on emissions. The car is a K reg Citroen BX. The car was given a Catalyst (closed loop) gas test although the car does not have a cat fitted or fuel injection and is a carburettor engine model. Not suprisingly it did not meet the cat standards but should it have been given a different test. - A Bolton
To decide whether or not a vehicle should have a catalytic test the MOT garage will have an official booklet which clearly states not only which vehicles should be so tested but also what the limits should be for that specific vehicle.
Certainly most ‘K’ registered vehicles would need a cat test. I suggest you go to the garage and ask them to again check in their emissions booklet with respect to your vehicle.
As catalytic converters are not cheap it is not unknown for people to replace the cat with a ‘normal’ exhaust box. On the other hand that your car is not fuel injected would imply that it never did have a cat in the first place. Could somebody have changed the engine during the vehicle’s history?
Your final alternative is to telephone the VOSA ‘hotline’ the number will be on the reverse of the MOT failure certificate, and ask their advice. - MOTT
EMISSIONS FAILURE
My car has just failed theMOT Test on emissions. The car is a K reg Citroen BX. The car was given a Catalyst (closed loop) gas test although the car does not have a cat fitted or fuel injection and is a carburettor engine model. Not suprisingly it did not meet the cat standards but should it have been given a different test. - A Bolton
To decide whether or not a vehicle should have a catalytic test the MOT garage will have an official booklet which clearly states not only which vehicles should be so tested but also what the limits should be for that specific vehicle.
Certainly most ‘K’ registered vehicles would need a cat test. I suggest you go to the garage and ask them to again check in their emissions booklet with respect to your vehicle.
As catalytic converters are not cheap it is not unknown for people to replace the cat with a ‘normal’ exhaust box. On the other hand that your car is not fuel injected would imply that it never did have a cat in the first place. Could somebody have changed the engine during the vehicle’s history?
Your final alternative is to telephone the VOSA ‘hotline’ the number will be on the reverse of the MOT failure certificate, and ask their advice. - MOTT
I used to be a tester until 18 months ago. It was at first decided that all cars registered after 01/08/1992 would need to meet the cat emission regs but some makers were unable to do this in time. As VOSA didn't have complete info from the makers, it was then decided that all cars registered after 01/08/1995 had to meet the regs but cars registered between the two dates had to meet the regs if they were on certain list. As the years have gone on, VOSA have greatly expanded this list as they have recieved info from the vehicle makers, so it is often the case that some older cars now need to meet the regs when they did not in the past.
Edited by oakdale on Wednesday 29th October 09:20
Also found this :
Passenger cars:
First used before 1/8/1975 - Visual test only. Failure for excess idle speed, dense blue or black smoke for 5 seconds at idle or during acceleration up to 2500rpm or half engine max speed whichever lowest.
First used between 1/8/75 and 31/7/86 - meter test CO <=4.5%, HC<=1200ppm.
First used between 1/8/86 and 31/7/92 - meter test CO<=3.5%, HC<=1200ppm.
First used between 1/8/92 and 31/7/94 - advanced emission test (CAT) if its running on petrol when presented, to the vehicle specific limits usually around CO<=0.3%, HC<=200ppm and Lambda 0.97 - 1.03. Remember from 1st August 2001 a basic emission test will be carried out initially.
Basic fault finding:
Basic fault finding for advanced emission test failures:
If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
So yours should be covered under the non catalist cars, be allowed < 3.5% CO - which you seem to have and HC (hydro carbon) of < 1200 parts per million.. you did not tell us that value.
Passenger cars:
First used before 1/8/1975 - Visual test only. Failure for excess idle speed, dense blue or black smoke for 5 seconds at idle or during acceleration up to 2500rpm or half engine max speed whichever lowest.
First used between 1/8/75 and 31/7/86 - meter test CO <=4.5%, HC<=1200ppm.
First used between 1/8/86 and 31/7/92 - meter test CO<=3.5%, HC<=1200ppm.
First used between 1/8/92 and 31/7/94 - advanced emission test (CAT) if its running on petrol when presented, to the vehicle specific limits usually around CO<=0.3%, HC<=200ppm and Lambda 0.97 - 1.03. Remember from 1st August 2001 a basic emission test will be carried out initially.
Basic fault finding:
Basic fault finding for advanced emission test failures:
If a vehicle fails for high CO at idle and /or fast idle then.... if Lambda is too low, the mixture is too rich. This can be caused either by a misfire or by a faulty Lambda sensor. If it's running very rich, the 02 and HC will be higher than normal.
if it has a high Lambda and high 02 (0.5 to 1.5%), the "CAT" could be faulty. Before condemning it make sure its hot enough to work, the Lambda and other sensors are working OK and the exhaust downpipe hasn't got any leaks.
if the vehicle fails for high HC then ...if the CO passes, the vehicle is probably misfiring. Or if the CO fails and the Lambda reading is too low, the mixture is probably too rich and it may also be misfiring.
if the CO fails, the Lambda reading is high and the O2 reading is high (0.5 to 1.5%) the "CAT" could be faulty. Again check out the simple measures above before condemning it.
if the Lambda fails then...if its too high the Lambda sensor may be faulty, the mixture may be too weak or there may be a hole in the exhaust downpipe. If Lambda is too low the sensor may be faulty, the mixture may be rich or the vehicle may be misfiring.
So yours should be covered under the non catalist cars, be allowed < 3.5% CO - which you seem to have and HC (hydro carbon) of < 1200 parts per million.. you did not tell us that value.
My Sierra (2.0iDOHC) failed on CO emissions 2 years ago. The garage had me running round all over the place looking for injection specialists. Load of pants really. From memory, if you look under the bonnet, driver's side, bolted to the inside of the wing is a little adjuster screw. That is the CO adjuster. I think the potentiometer track gets dirty and the connection goes high resistance or something. Either way, there is a fair amount of adjustment available. I pointed this out to the lads at the garage and they were more than happy to tweak it and send me on my way with an MoT and no extra fee.
Hi
What is "Lambda"? I know the sensor is in the exhaust. Is it something to do with protecting the cat? Are only catalysed cars fitted with a Lambda sensor?
My friend's old Honda Concerto is struggling to get through an MOT as the Lambda reading is too high for the measuring device. The garage is going to have a go at the emissions to see what's wrong. The sensor might not be working. Is this an expensive fix.
I don't believe this K registered car has a catalyist.
I noticed that the car is more sluggish than it used to be.
I'd be grateful if someone could explain in layman's terms what all this is about!
Jonathan
What is "Lambda"? I know the sensor is in the exhaust. Is it something to do with protecting the cat? Are only catalysed cars fitted with a Lambda sensor?
My friend's old Honda Concerto is struggling to get through an MOT as the Lambda reading is too high for the measuring device. The garage is going to have a go at the emissions to see what's wrong. The sensor might not be working. Is this an expensive fix.
I don't believe this K registered car has a catalyist.
I noticed that the car is more sluggish than it used to be.
I'd be grateful if someone could explain in layman's terms what all this is about!
Jonathan
Lambda 1.0 is the ideal air fuel ratio (AFR) which in the case of petrol is 14.7:1 (14.7lbs of air to 1lbs of petrol).
When I say ideal I mean the best compromise between power, economy, pollution etc.
An AFR 12.5 - 13.3 = Lambda 0.85 - 0.90 would give best power.
The lambda sensor measures the remaining oxygen in the exhaust gas to determine if the mixture was correct. Ideally just enough fuel will have been used to burn all the oxygen.
Steve
When I say ideal I mean the best compromise between power, economy, pollution etc.
An AFR 12.5 - 13.3 = Lambda 0.85 - 0.90 would give best power.
The lambda sensor measures the remaining oxygen in the exhaust gas to determine if the mixture was correct. Ideally just enough fuel will have been used to burn all the oxygen.
Steve
That is helpful. Thank you.
The garage have done something and I have an MOT which is the main thing. The car is running FAR better. I have a feeling that the thing was running far too rich.
I'll ask them tomorrow if this was the case and also what they actually did!
I knew the engine wasn't knackered. The reading for particulates was well within the limits.
The garage have done something and I have an MOT which is the main thing. The car is running FAR better. I have a feeling that the thing was running far too rich.
I'll ask them tomorrow if this was the case and also what they actually did!
I knew the engine wasn't knackered. The reading for particulates was well within the limits.
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