Failed MOT on Emissions
Discussion
I have just been told by the garage my S1 Elise has failed the MOT on emissions. On the natural idle test, it blew 3.26 %vol CO - the pass is 0.5 %vol.
When I bought the car, it was de-catted. I was told it would pass but that was incorrect:
I fitted a cat from www.cats4less.co.uk which cost me £53.30 and got the following result:
Is it possible catalytic converters costing just over fifty quid are a bit pants and it has failed early, or could there be something else I should try looking at?
Thanks!
When I bought the car, it was de-catted. I was told it would pass but that was incorrect:
I fitted a cat from www.cats4less.co.uk which cost me £53.30 and got the following result:
Is it possible catalytic converters costing just over fifty quid are a bit pants and it has failed early, or could there be something else I should try looking at?
Thanks!
Scuffers said:
hang on, let me get this right...
the first printout is from the car without a CAT, and the second with said cheap CAT?
if yes, then what's the problem? no CAT = fail (no matter what internet myths tell you).
Yes, but they are both old ones. It has been in today with the same cat fitted that it has passed with every time since, but it has now blowing high again.the first printout is from the car without a CAT, and the second with said cheap CAT?
if yes, then what's the problem? no CAT = fail (no matter what internet myths tell you).
Ganglandboss said:
Scuffers said:
hang on, let me get this right...
the first printout is from the car without a CAT, and the second with said cheap CAT?
if yes, then what's the problem? no CAT = fail (no matter what internet myths tell you).
Yes, but they are both old ones. It has been in today with the same cat fitted that it has passed with every time since, but it has now blowing high again.the first printout is from the car without a CAT, and the second with said cheap CAT?
if yes, then what's the problem? no CAT = fail (no matter what internet myths tell you).
Sorry - no scanner at the moment so I've had to photograph it with my phone.
I only had what they told me on the phone when I posted - the actual reading is different. When I collected the car, he told me they had to abandon the test as the car was overheating and there was a crack in the reservoir. The hand written numbers are the fast idle and natural idle figures.
I have had a look at the car and there is a very thin crack in the reservoir and fluid is weeping out very gently. I have driven the car home, 5 miles in stop-start traffic, getting out to check every now and again. The car showed no signs of overheating.
Looking at the printout, the oil temp is only 18.3 degrees C but the MOT test manual says:
"Engine speed and temperature
[i]When checking exhaust emissions, the engine must be at its normal idle speed and normal operating temperature.
Engine speeds and temperature can be assessed either subjectively or by reference to manufacturer's or other reliable data[/i]
I only had what they told me on the phone when I posted - the actual reading is different. When I collected the car, he told me they had to abandon the test as the car was overheating and there was a crack in the reservoir. The hand written numbers are the fast idle and natural idle figures.
I have had a look at the car and there is a very thin crack in the reservoir and fluid is weeping out very gently. I have driven the car home, 5 miles in stop-start traffic, getting out to check every now and again. The car showed no signs of overheating.
Looking at the printout, the oil temp is only 18.3 degrees C but the MOT test manual says:
"Engine speed and temperature
[i]When checking exhaust emissions, the engine must be at its normal idle speed and normal operating temperature.
Engine speeds and temperature can be assessed either subjectively or by reference to manufacturer's or other reliable data[/i]
The oil temp was likely not used as its a pita a lot of the time so thats probably ambient temp. If the co is up at 3.0% or more its not just the cat at fault as it could not deal with that level anyway.
As said you need to see the lambda reading, i guess its about 0.900 or less.. You might have a poor o2 sensor but i am not up on the Elise engine management system....does it have a mass air meter?? What about that exhaust,no cracks before the o2 sensor?
As said you need to see the lambda reading, i guess its about 0.900 or less.. You might have a poor o2 sensor but i am not up on the Elise engine management system....does it have a mass air meter?? What about that exhaust,no cracks before the o2 sensor?
I spoke to someone at the garage earlier - the tester wasn't there but the bloke I spoke to was with him as it was being done and he knew a lot more than the bloke I spoke to when I picked it up. Apparently the car was brought up to temperature; he said they don't dip the temperature probe in the oil if they can get a reading in the car and the 18 degrees on the printout is the ambient garage temperature. He said he had a look in the tail pipe where he saw bits of broken up ceramic material so it looks like I will be taking it out this weekend for a look.
I am still at work so I will have a proper look when I get home.
I am still at work so I will have a proper look when I get home.
Hello there
I'm hoping someone might be able to point me in the right direction after my car failed the MOT emmision test (twice on Lambda and once on CO).
The readings were as follows
Fast idle test 1
Engine speed not checked
CO 0.13% Pass
HC 39ppm Pass
Lambda 1.229 Fail
Fast idle test 2
Engine speed not checked
CO 0.65% Fail
HC 50ppm Pass
Lambda 1.139 Fail
Natural idle test
Engine speed not checked
CO 0.03% Pass
From my level of understanding, the Lanbda results suggest there is too much oxygen post combustion.
How do people decide whether to investigate a possible exhaust manifold leak, faulty lambda sensor, problem with fuelling etc?
Is there a better way than simply guessing which of the potential issues is causing the problem and outplaying for say a new Lambda sensor when that may well not be the issue?
Surely there is a data dependent way to approach this rather than blindly stumbling over the right answer?
Any advice is much appreciated.
I'm hoping someone might be able to point me in the right direction after my car failed the MOT emmision test (twice on Lambda and once on CO).
The readings were as follows
Fast idle test 1
Engine speed not checked
CO 0.13% Pass
HC 39ppm Pass
Lambda 1.229 Fail
Fast idle test 2
Engine speed not checked
CO 0.65% Fail
HC 50ppm Pass
Lambda 1.139 Fail
Natural idle test
Engine speed not checked
CO 0.03% Pass
From my level of understanding, the Lanbda results suggest there is too much oxygen post combustion.
How do people decide whether to investigate a possible exhaust manifold leak, faulty lambda sensor, problem with fuelling etc?
Is there a better way than simply guessing which of the potential issues is causing the problem and outplaying for say a new Lambda sensor when that may well not be the issue?
Surely there is a data dependent way to approach this rather than blindly stumbling over the right answer?
Any advice is much appreciated.
As you have already identified, lambda is the issue.
I would suggest the first test for you is to look for the air leak in the exhaust, wherever it us it will be significant.
To do this just ram a rag up the tailpipe at idle and listen for it.
Once you have found and fixed this, then a quick retest to check that lambda is back in target, if not, then assume the sender is out (although if it is out you should have the mil light on if your car has one?)
Looking at the CO and HC figures, your cat seems to be working ok.
I would suggest the first test for you is to look for the air leak in the exhaust, wherever it us it will be significant.
To do this just ram a rag up the tailpipe at idle and listen for it.
Once you have found and fixed this, then a quick retest to check that lambda is back in target, if not, then assume the sender is out (although if it is out you should have the mil light on if your car has one?)
Looking at the CO and HC figures, your cat seems to be working ok.
Hello there
The exhaust is not leaking. I failed to find any leak apart from light blowing from the back box drain hole(which must be normal) nd this has now been confirmed independently by a garage.
Therefore with excessive oxygen levels in the exhaust during he missions test, where do I look next for the potential problem?
I presume therefore my car is running too lean. It's odd as it appears to run very well with plenty of power and no stuttering.
Lambda sensor?
Fuelling?
Something else?
Cheers
Duncan
The exhaust is not leaking. I failed to find any leak apart from light blowing from the back box drain hole(which must be normal) nd this has now been confirmed independently by a garage.
Therefore with excessive oxygen levels in the exhaust during he missions test, where do I look next for the potential problem?
I presume therefore my car is running too lean. It's odd as it appears to run very well with plenty of power and no stuttering.
Lambda sensor?
Fuelling?
Something else?
Cheers
Duncan
what car is it?
does it have a MIL light and if yes, is it on?
from the sounds of it, if no leak found then the lambda sensor is reading wrong - odd bit it that when this happens, the ECU will just fail the sensor and go open loop, this usually means that it will be running rich, not lean....
does it have a MIL light and if yes, is it on?
from the sounds of it, if no leak found then the lambda sensor is reading wrong - odd bit it that when this happens, the ECU will just fail the sensor and go open loop, this usually means that it will be running rich, not lean....
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