Emission test fail. Have they not tested correctly?

Procrastinator333

Hello, I have an 11 plate BMW 1 series. It just failed the MOT on emissions. Lambda too high, about 2. The pass range was up to 1.03.

However, upon searching the infinite wisdom of google I found other people who had a similar experience. The issue turned out to be that the test center had not set the equipment correctly.

I looked on the paperwork for the car and I also used a VIN Checker:

http://www.bmwvin.com/

Both of these sources show that it is an N43 engine.

So I looked in here:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/348035/18th-edition-emissions-book-complete.pdf

Page 11. That lists the N43 BMW 1 series as min and max lambda of 0.7 to 4. So the score of 2 is well within that range.

I'm posting this up here in case anyone who knows about cars can see an error in what I have done before I contact the garage.

Thank you in advance for any information you have!

reeac

I think that that figure of 4 in the tables must be a typo.. I can't imagine that an engine could run with a mixture so far from the stoichiometric value of unity. Similarly, I find it difficult to believe your test figure of 2.

captainawsome

The garage have done a BET test on the vehicle. They need to do a full catalyst test to pass an n43 engine which takes a few minutes longer.

The n43 is a lean burn direct injection engine. When the revs are held and the engine is under light load it will switch from homogeneous to stratified mode and the the lambda will go off the scale. Nothing wrong with the car, just needs a full cat test carrying out and will pass

Procrastinator333

http://www.motester.co.uk/mot-workshop-magazine-online/mot-workshop-magazine/mot-workshop-37-lean-burn-engines

That link talks about it captain awsome. And it says in stratified mode it will run with a lambda 1.6 - 4.0.

Now im going to have to tell the garage that they dont know what they are doing. I bet this will go down well!

bigjl

Procrastinator333 wrote: »

http://www.motester.co.uk/mot-workshop-magazine-online/mot-workshop-magazine/mot-workshop-37-lean-burn-engines

That link talks about it captain awsome. And it says in stratified mode it will run with a lambda 1.6 - 4.0.

Now im going to have to tell the garage that they dont know what they are doing. I bet this will go down well!

I must admit I would consider trying to find a BMW specialist that does MOTs as they are more likely to know how to test the vehicle correctly.

I tried to buy parts for a 116i on a 60plate and it was a nightmare, there were different possibilities, 1.6 or 2.0 I think.

I long for the days when a 116i would have had a 1.6 engine.

salubrious

As has been pointed out, Those vehicle specific readings for the BMW are right. The tester would have known this if he had followed procedure correctly.

Any vehicle that fails a BET test, must then go through what they call an extended test and vehicle specific data (test limits) must be applied, Usually the gas analyser will have this information built into it's software, so it's all part of the testing process.

In the case of the BMW, there is a huge difference in the Lambda tolerance, hence a fail under a BET test becomes a pass using the specific data.

Rookie mot tester mistake to be honest.

mrmot

Some BMW engines are allowed a Lambda value up to 4. The problem often arises when the tester is under time pressure and they haven't got the resources to hand to identify the engine code, so under engine type they click 'other'.

The garage should have a paper copy of the In Service Emissions Book, if they open it to BMW and look at the maximum Lambda column, they will see the figure 4 for some engines as opposed to 1.03.

Interestingly in that book, you won't find Suzuki listed.

Procrastinator333

Garage have agreed they did the trst wrong. Will test it again later in the week. So should be all good this time. i can stop worrying that it might need an expensive trip to bmw.

lazer-zxr

On a similar note, my 2002 2.0hdi Citroen just passed the emissions test .... but goodness knows how. Theres a lot of black smoke comes out of it under hard acceleration. I would've thought this would have failed?

Not that I'm complaining, I'm just confused.

Rain_Shadow

lazer-zxr wrote: »

On a similar note, my 2002 2.0hdi Citroen just passed the emissions test .... but goodness knows how. Theres a lot of black smoke comes out of it under hard acceleration. I would've thought this would have failed?

Not that I'm complaining, I'm just confused.

I'd be interested to know. My Pug 405 was the same. Maybe it is to do with whether the engine is under significant load (when accelerating on the road) or revving freely (on the test)?