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Discussion Starter · #1 ·
Hi all,

My car failed it's MoT today on emissions.

Results as follows.

Fast Idle Test:
Limits Reading FAIL
Engine Speed 2450-3050 rpm 2724 rpm Pass
CO max 0.30% 1.35% Fail
HC max 200 ppm 138ppm Pass
Lambda 0.95-1.09 0.98 Pass


Second Fast Idle Test
Limits Reading FAIL
Engine Speed 2450-3050 rpm 2715 rpm Pass
CO max 0.30% 1.57% Fail
HC max 200 ppm 115ppm Pass
Lambda 0.95-1.09 0.97 Pass


Natural Idle Test
Limits Reading PASS
Engine Speed 725-1025 rpm 884 rpm Pass
CO max 0.50% 0.48 Pass


Overall Result: FAIL


Any Ideas??
 

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Cat's not hot enough, take it for a good run before next cat test, 50 - 60 miles per hour in third gear gets the cat nice and hot, then straight in for the cat test after the run.

DaveH
 

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Discussion Starter · #5 ·
Respot said:
Cat's not hot enough, take it for a good run before next cat test, 50 - 60 miles per hour in third gear gets the cat nice and hot, then straight in for the cat test after the run.

DaveH

Went straight for test after a 75 mile run on M-Way and fast dual carriageway. Made sure I'd blasted the Feck out of it, and emissions was the first test they did.

One thing he said, was that he thinks it could be the coolant temp sensor.

Major, if you are on-line what are your views??
 

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Hi, The engine is running rich for some reason. It is possible that the coolant sensor is faulty, but I would have thought you would have noticed some other problems, at least poor mpg if nothing else. I would check the oxygen sensor is working by checking for a fluctuating voltage output with a multimeter.

cheers gary :)
 

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Discussion Starter · #7 ·
Gforce said:
Hi, The engine is running rich for some reason. It is possible that the coolant sensor is faulty, but I would have thought you would have noticed some other problems, at least poor mpg if nothing else. I would check the oxygen sensor is working by checking for a fluctuating voltage output with a multimeter.

cheers gary :)

Gary,

Thankyou you have confirmed my theory. My MPG has been 5hit. Lambda (O2) sensor is OK. So I have changed the CTS. I have it booked into an independent MGR centre for a diagnostic to see if anything else is faulty.

Will let you know the results soon.
 

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Discussion Starter · #9 ·
Major Ingram said:
I'd be suspecting the oxygen sensor, myself..

How do you know it's OK?

Lambda is within limits, HC is within limits. Also when idling (full closed loop) emissions are ok. Just fails at what they call a fast idle (when my car idles between 2450 & 3050 rpm. I will really worry!)
 

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when you have an MOT the emissions test is carried out towards the end of the test session, would you not get a better read out if this was done first, when you arrive with a hot engine.
 

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at work some engines get a reved up for a wille if its cold or throwing the emitions out to try and get it to pass the emitions part so asuming they were not in a real bad mood then its more likely there is a sensor out or something
 

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Discussion Starter · #12 ·
Ken said:
when you have an MOT the emissions test is carried out towards the end of the test session, would you not get a better read out if this was done first, when you arrive with a hot engine.

Emissions should be done first. Mine were after a very quick check of the lights.

However it still failed
 

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cjmillsnun said:
Emissions should be done first. Mine were after a very quick check of the lights.

However it still failed
no they should be done at normal operating temp of the engine not just water temp but when the engine is properly walm, this is quite often the last thing done due to pepole driveing 3-4 miles to mot and never walming the engine
 

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Car needs to be put back on the exhaust analyser for a normal four gas reading - HC, CO, O2 and Lambda - O2 being the important one here.

Are you also able to test your lambda sensor - see if it's switching ok.

DaveH
 

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cjmillsnun said:
Emissions should be done first. Mine were after a very quick check of the lights.
Ah, myself being an MOT Manager, there is no "set routine" or point in the test as to when the emissions test, or any other part of the test should be carried out.
 

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ml.williams said:
no they should be done at normal operating temp of the engine not just water temp but when the engine is properly walm, this is quite often the last thing done due to pepole driveing 3-4 miles to mot and never walming the engine
Correct - if the car fails the BET test, then a full catalyst test is undertaken, when the oil temperature (indicating full engine temperature has been reached....) of 80 degrees (min) has been attained.

Very often, if a car fails the BET then a full cat test results in a test pass.
 

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Discussion Starter · #17 ·
Major Ingram said:
Correct - if the car fails the BET test, then a full catalyst test is undertaken, when the oil temperature (indicating full engine temperature has been reached....) of 80 degrees (min) has been attained.

Very often, if a car fails the BET then a full cat test results in a test pass.

OK it's sorted. It was the Lambda sensor.

Frightening bill though! £244.74
 
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