MOT Fail: Carbon Monoxide at Idle and 2nd Fast Idle!
- Thread starter as400
- Start date
It doesn't say what the oil temperature is, it should be at about 90°c I think, that could be a contributing factor.
- Joined
- Dec 16, 2017
- Points
- 138
I wonder why there are just lines through the oil temperature sections?
Could also be a failed O2 sensor or the Cat. It's good practice to take it for an Italian Tune prior to a MOT, especially on lightly used cars.
- Joined
- Dec 8, 2011
- Points
- 145
This is essential. It's also essential to have a tester who will persevere to try to make it pass. That's why you should stick to the one tester, and not just use the latest cheap offer.
On my last MOT, my tester spent about 30 minutes trying many different things to make it pass. I've rewarded him with the chance to test my Smart car, even though I could have had a freeby in a different garage.
Simply because they didnt test the oil temperature on the BET Test. They HAVE TO when doing a Cat test.
Tony.
I think they're supposed to get the engine really hot to be sure that the cat has reached working temperature.
But I wonder if some garages are reluctant to get a seldom used z3 really hot in case some perished bit of plastic in the cooling system goes pop and they find themselves being blamed for it.
But I wonder if some garages are reluctant to get a seldom used z3 really hot in case some perished bit of plastic in the cooling system goes pop and they find themselves being blamed for it.
You could be right, but, all you have to do is explain to the presenter of the vehicle what needs to happen and the possible risks involved.
Tony.
Tony.
- Joined
- Dec 16, 2017
- Points
- 138
I have been using this garage for a number of years for maintenance and repair on several cars, usually go to Halfords Autocentre as get discount via the AA, but this local garage charges the full fat £54.
Car had been sitting for 2 months and tester was only 5 minutes away...not ideal I guess.
What are the most common issues that cause this?...interested to hear what people do to rectify this failure?
As your CO levels were really high, especially at normal idle (20 times the limit), there must be something wrong, either with the cat or something else.
It could just be lack of use and requires a good warm up and drive to 'blow the cobwebs away'.
I would take out the air filter, check it is OK, along with the air intake tubing. If a car is unused for periods, it is not uncommon for 'creatures' to make nests in a filter housing or intake pipework. A big leaf in the air intake pipe could easily restrict airflow enough to cause a problem. Ask me how I know!
Check plugs are in good nick and check the gaps. Make sure MAF sensor is seated correctly, etc.
It could just be lack of use and requires a good warm up and drive to 'blow the cobwebs away'.
I would take out the air filter, check it is OK, along with the air intake tubing. If a car is unused for periods, it is not uncommon for 'creatures' to make nests in a filter housing or intake pipework. A big leaf in the air intake pipe could easily restrict airflow enough to cause a problem. Ask me how I know!
Check plugs are in good nick and check the gaps. Make sure MAF sensor is seated correctly, etc.
- Joined
- Dec 16, 2017
- Points
- 138
Thanks it had a major service 6 months ago with (I guess/hope) everything getting changed.
Will ask them to start with swapping the lambda sensor as that's not too expensive, previous MOT levels were all easily within tolerance, its only done 600 miles since....no warning lights.
Just trying to ascertain how many lambda/O2 sensors the car has?
Will ask them to start with swapping the lambda sensor as that's not too expensive, previous MOT levels were all easily within tolerance, its only done 600 miles since....no warning lights.
Just trying to ascertain how many lambda/O2 sensors the car has?
Yes, that is correct.
Tony.
Tony.
My car has failed mot on emissions in the past under previous ownership when it was hardly ever being used. I’ve been taking it to a garage 45min drive away so it is fully warmed up prior to the test.
- Joined
- Dec 8, 2011
- Points
- 145
Check for blockages and leaks. I wouldn't worry about spark plugs or O2 sensors yet.
You need to get it warmed-up, properly. Coolant is up to temp in about 5-10 minutes, but oil takes at least double that. Then, you can give it the beans. Don't mess around on dual carriageways - you want to be holding it at 60 in second gear for at least 5-6 seconds under load (i.e uphill and around the twisties), and really working the engine. It won't break.
Get it on the exhaust analyser as soon as you get back to the MOT tester. The tester may think that his equipment is faulty, as the readings could be zero.
My MOT tester is also 5 minutes down the road, but it always takes me an hour to get there. Last year I did 35 miles between MOTs (1 mile home from MOT, 34 miles to the MOT), and passed with minimal readings.
My 1998 2.8 always had its test performed by the local BMW dealer, and every year the CO level exacty doubled - i found it very difficult to believe that it was exactly double that of the previous year! Of course, it was within limits, but the oil temperature was not stated. On these figures, by 2004 it would have failed, and 'Sir' would be invited to pay for a new exhaust system, or better still, buy a new car. It is illegal to understate the CO level to keep a 'dirty' car on the road, but it is not illegal to overstate the level . . .
When we moved to France the Controle Technique (French MoT) test uses a stiffer procedure, but still came up with zero CO, and has remained so ever since, and different test centres. Of course, they advise one to get the engine and catalyst hot before arrival for your appointed time, and oil temperature is always recorded - but the test centres do not sell parts.
It makes one think, doesn't it? Dealers have a vested interest in being pessimistic - trust them at your peril . . .
When we moved to France the Controle Technique (French MoT) test uses a stiffer procedure, but still came up with zero CO, and has remained so ever since, and different test centres. Of course, they advise one to get the engine and catalyst hot before arrival for your appointed time, and oil temperature is always recorded - but the test centres do not sell parts.
It makes one think, doesn't it? Dealers have a vested interest in being pessimistic - trust them at your peril . . .
- Joined
- Apr 1, 2016
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- 218
- Location
- Maybole , South Ayrshire
- Model of Z
- Z3 Individual Dakar / Orinoco Individual
New equipment in the market now which is much improved we have a number of centres running the bosch bea 950 analysers.
They plug into obd and everything is bar graphs on the screen so reads oil temp , engine revs etc through obd and wont let test proceed unless oil temp correct and during test ( petrol) revs must be kept between the graph lines or countdown timer resets.
On diesel same oil temp check then governer check ( this machine will make you rev the diesel to its set govener before allowing test commencement)
Then on print it will show for each rev
The oil temp , idle speed , max rev at limiter also how long it took to take rev to limiter and how long held .
When you rev it the revs show red on screen got to keep going till goes green .
As for the readings above without knowing the oil temperature difficult to make a proper judgement.
But lambda is low ( ideal is around 1.01 ) low is rich high is lean.
With reading as high as that at idle it would smell rich a good running 2.8 single or twin vanos should be good just mot'd a 2.8 single vanos with 120k emissions were spot on .
The tu 2.8 is a euro 3 engine so has 2 cats ( cyl 1 to 3 and 4 to 6 ) with 4 lambda 2 pre and 2 post cat then a y piece to merge to one and at rear a valved back box these are usually spot on for emissions
Do you have a code reader if so check for faults.
If nothing then may just be needing to get everything back to proper operating temperature to clean it out.
Stephen.
They plug into obd and everything is bar graphs on the screen so reads oil temp , engine revs etc through obd and wont let test proceed unless oil temp correct and during test ( petrol) revs must be kept between the graph lines or countdown timer resets.
On diesel same oil temp check then governer check ( this machine will make you rev the diesel to its set govener before allowing test commencement)
Then on print it will show for each rev
The oil temp , idle speed , max rev at limiter also how long it took to take rev to limiter and how long held .
When you rev it the revs show red on screen got to keep going till goes green .
As for the readings above without knowing the oil temperature difficult to make a proper judgement.
But lambda is low ( ideal is around 1.01 ) low is rich high is lean.
With reading as high as that at idle it would smell rich a good running 2.8 single or twin vanos should be good just mot'd a 2.8 single vanos with 120k emissions were spot on .
The tu 2.8 is a euro 3 engine so has 2 cats ( cyl 1 to 3 and 4 to 6 ) with 4 lambda 2 pre and 2 post cat then a y piece to merge to one and at rear a valved back box these are usually spot on for emissions
Do you have a code reader if so check for faults.
If nothing then may just be needing to get everything back to proper operating temperature to clean it out.
Stephen.