NCT Testing BMW's Incorrectly

Matt Simis

pippip wrote: »

If you open the Uk doc the op references it gives the exact figures for each model. The other two 118i engines are .7-1.03 but the specific engine the op has is listed as .7 - 4.

Kenny Logins wrote: »

Yeah, just reading now about titania oxygen sensors.
http://www.bmwownersclub.com/forums/topic/4369-lambda-sensors/

Right.. so the BMW guideline is referencing a Titania sensor.. which makes that value irrelevant as NCT use their own sensor. Also I fail to see how a manufacturers accepted tolerance for any sensor or emissions part trumps a Government required quality target.

George Dalton

As another poster already said the CO limit according to BMW and according to the VOSA in the UK is 0.2%

Since the OP's car recorded a figure of 1.39% it would seem that there is something wrong with the car.

Having said that the lambda figure certainly should have passed so the NCT have some explaining to do.

Interslice

George Dalton wrote: »

As another poster already said the CO limit according to BMW and according to the VOSA in the UK is 0.2%

Since the OP's car recorded a figure of 1.39% it would seem that there is something wrong with the car.

Having said that the lambda figure certainly should have passed so the NCT have some explaining to do.

Lambda: 0.96 (not between 0.97 and 1.03) fail
CO 1.39 vol % (above 0.20%) fail

Looks to me like they made the right call. Car appears to be running a bit rich. Them bmws figures look far too extreme to ever fail a test.


From the mot manual the OP posted, it would have failed that too.

The emissions limits to be met are specified for both the fast and normal idle tests.
At fast idle, CO must be at or less than 0.2%, HC at or less than 200 parts per million
(ppm), and the lambda value(1)
must be between 0.97 and 1.03. At normal idle, CO
must be at or less than 0.3%.

although it does mention it here for certain engine codes

116i 3 & 5 door Engine Code N43 B16 A 0.2 870 0.2 200 0.7 4 2700 60 2300 680
116i 3 & 5 door Engine Code N43 B20 A 0.2 870 0.2 200 0.7 4 2700 60 2300 680
116i 5 door Engine Code N45 B16 A 0.2 850 0.2 200 0.97 1.03 2700 60 2300 600
118i 5 door Engine Code N46 B20 B 0.2 850 0.2 200 0.97 1.03 2700 60 2300 600
118i 3 & 5 door, Convertible Engine Code N43 B20 A 0.2 870 0.2 200 0.7 4 2700 60 2300 680
120i 5 door Engine Code N46 B20 B 0.2 850 0.2 200 0.97 1.03 2700 60 2300 600
120i 3 & 5 door, Coupé / Convertible Engine Code N43 B20 A 0.2 870 0.2 200 0.7 4 2700 60 2300 680

Duke of Speed

there are 2 different voltage reading lambas fitted to all cars narrow band sensors,and wideband sensors which are the more modern sensor fitted to newer cars. narrow band lambda is a 0 to1volt sensor and wideband is a 0 to 5volt sensor narrow band has a small range around 14.7 afr which is total combustion of the fuel which is universally known as lambda 1 or stoich and in ideal conditions is achieved between 0.97v and 1.03v on a narrow band and should achieve under 0.3 CO% the wideband has a wide range of 8afr to 22afr which is used universally to map cars and has a finer resolution and reacts faster to keep the emissions in check so the range in voltage is .7volt to 4volt 3.7volts is roughly 14.7 afr or lambda 1 and now you can see the differences of 0.97 to 1.03 and .7 to 4v both achieve the one emissions under 0.3 which is the pass rate or lamda 0.97 to lambda 1.03 which is the tolerance as the poster dougie said so the op is quoting lambda voltage for his car which has a wideband lsu bosch sensor older lambda sensors have a life of approximately 60k miles your car has a fault and if you check the live data on a scan tool it will give the voltage of the lambda to see is it working correctly bmw have either lambda as shown by the chart of models hope this helps

hi_im_fil

But the nct test use their own sensor which gives the lambda reading. They don't rely on the BMW sensor. So it should still be within the 0.97-1.03 range as far as I can see.

Duke of Speed

the nct uses a 5 gas analyser which every garage and car manufacturer use even central heating oiil bolier techniciians to measure the emitting gases the lambda sensors help achieve these results. the lambsa sensor feeds a signal to the ecu so the ecu can achieve these standards the nct does not test the bmw sensor it tests the emissions as i said lambda 1 is a measure of enissions

George Dalton

The OP is not quoting voltage. They are quoting the actual lambda spec for their car (assuming it is the N43 engine) of 0.7-4.0.

Duke of Speed

there is no such thing as lambda 4 in emissions i map cars for a living and have to achieve these values to pass nct what bmw are quoting in there specs are the operating voltage that the ecu uses from a 5v lambda which is a sensor all tuners use no rocket science here. this bmw guy has a fault and if he brings it to a garage it can be fixed i deal with this problem every day as does every other garage

George Dalton

The BMW N43 engine is a lean burn engine and has a much wider lambda spec than any other engine I know of. Lambda figures of 2-2.5 are perfectly normal.

You don't have to take my word for it. If you deal with this every day then you should have access to Autodata or similar. Go on to Autodata and look up the emissions spec for a BMW with an N43 engine. It clearly says 0.7-4.0 whereas practically every other petrol engine is 0.97-1.03 as you say.

Now all of this doesn't take away from the fact that I still reckon there is something wrong with the OP's car. That CO figure of 1.39% is way too high. For all we know the OP's car may not even have the N43 engine, it could have the N46 which does operate within the normal lambda range of 0.97-1.03.

Duke of Speed

most cars george have wide band lambda the 1.8t lambda is the sensor used by innovate motorsport widebands they work from 8afr to 22 afr but your only need 14.7 to 16afr for cruising emissions the wide band only gives the ecu the scope to read wider ranges and react faster and more stable for can bus on the newer cars to achieve better control. any fuel, ethanol included at stoich gives lamda 1 but the afr differs, bmw is no different to any other car using wideband as i said i map them. this thread is about a guy who says the nct are wrong which he is going to find out is not the truth he obviosly does not understand the emissions test ask any tuner with a rolling road if lambda 1 is 14.7 lambda 2 in theory would be an afr of 29 to 1 which is 29 parts of air to 1 part of fuel the engine would not run right and burn pistons lean burn engines run between 15 and 16.5 to 1 afr non turbo because of detonation

George Dalton

You don't need to explain to me about AFR or wideband lambdas believe me.

Lose the condesending attitude and look up the emissions specs for the N43 engine and then come back on here and tell us what it says.

Duke of Speed

george i have no condesensending attitude i speak facts and have no interest in offending anyone i came on here to participate in a discussion on this thread and provide answers thats what this site is here for i believe but theres always personal nastiness around, mods warned a poster already on this thread, its not a besting match, maybe we should tell the op whats wrong with his car plenty posters have given there opinion i gave mine bmw say under .2 co% no differnt to any other car, this car is over 1% fail

George Dalton

When I first read this thread I had the same opinion as you. Then I did some research and realised I was wrong in my opinion.

Have a look at the attached picture. I took a screenshot of the N43 emissions specs from Autodata.

Duke of Speed

ok george i see what your saying the 0.2 is the important one here which is the emissions we all agree on that. The 0.7 to 4 is lambda stated in voltage range. an awful lot of people mix lambda 1 unit as opposed to lambda voltage if i stick a voltage meter into sensor signal wire on this model the voltage should fluctuate between 0.7 and 4v to be in tolerance of ecu limits, to give me 0.2 co% so these facts are correct george if i go to another bmw with a narrowband 1v lambda it will be .97 to 1.03 to achieve the 0.2co% lambda voltage and lambda are confusingly different. until you get your head around it it took me time to, when studying it george

djimi

Any chance you could punctuate your posts Duke? Its very hard to read a block of unpunctuated text like that.

Duke of Speed

djimi wrote: »

Any chance you could punctuate your posts Duke? Its very hard to read a block of unpunctuated text like that.

my apologies djimi not good with typing will do in future

Old diesel

Looking forward to hearing the eventual outcome with this - whatever it is - fault with car - or with NCT

Very interesting stuff

Duke of Speed

Old diesel wrote: »

Looking forward to hearing the eventual outcome with this - whatever it is - fault with car - or with NCT

Very interesting stuff

it would be great if the op told us what diagnostics he has done on the car. and if its logging faults, otherwise its back to basic electronics to fix it. tThese cars are well known for throwing up faults where the fault is not the obvious sensor

dougie-lampkin

George Dalton wrote: »

The BMW N43 engine is a lean burn engine and has a much wider lambda spec than any other engine I know of. Lambda figures of 2-2.5 are perfectly normal.

You don't have to take my word for it. If you deal with this every day then you should have access to Autodata or similar. Go on to Autodata and look up the emissions spec for a BMW with an N43 engine. It clearly says 0.7-4.0 whereas practically every other petrol engine is 0.97-1.03 as you say.

Now all of this doesn't take away from the fact that I still reckon there is something wrong with the OP's car. That CO figure of 1.39% is way too high. For all we know the OP's car may not even have the N43 engine, it could have the N46 which does operate within the normal lambda range of 0.97-1.03.

Is it possible it's an incorrect figure from BMW for the N43 engine? BMW haven't changed the physical properties of petrol, an AFR of 60:1 is in no way acceptable, lean burn or not. And if it is a lean burn engine, why does it consider as rich as 10:1 acceptable? You'd be pushing visible lumps of carbon out of the exhaust at 10:1. It sounds to me like 0.7 - 4 is the sensor's range, not the emissions limit, and it's been mistakenly published as the emissions limit.

Kenny Logins

dougie-lampkin wrote: »

It sounds to me like 0.7 - 4 is the sensor's range, not the emissions limit, and it's been mistakenly published as the emissions limit.

I thought that was established already, or am I getting confused again? :pac:

challengemaster

dougie-lampkin wrote: »

It sounds to me like 0.7 - 4 is the sensor's range, not the emissions limit, and it's been mistakenly published as the emissions limit.

That may be the case, but BMW are standing by the figure (as per OP) so unless BMW correct the figure, it seems the NCT doesn't have a leg to stand on with regards the lambda reading.

dougie-lampkin

Kenny Logins wrote: »

I thought that was established already, or am I getting confused again? :pac:

I didn't think anything was established yet. BMW seem to be quoting a figure that makes no sense.

challengemaster wrote: »

That may be the case, but BMW are standing by the figure (as per OP) so unless BMW correct the figure, it seems the NCT doesn't have a leg to stand on with regards the lambda reading.

Surely common sense can be applied in this situation, in that the BMW figures cannot possibly be correct? The highest values I came across (other than BMW's) on that VOSA document on a quick skim were some Ford engines, that can run on 1.09 (16:1). I don't believe BMW are standing over the figure just because the OP received a computer printout from a desk jockey.

challengemaster

Something on paper trumps common sense, particularly when that paper has BMW written all over it.

BuzzFish

I'm sure I've seen the OP on the N7 a few times, Usually shouting and screaming in his car while jumping between lanes trying to shave 5 mins off the journey home He needs a snickers.

galwaytt

challengemaster wrote: »

Something on paper trumps common sense, particularly when that paper has BMW written all over it.

Ultimate Writing Machine then

Interslice

dougie-lampkin wrote: »

I didn't think anything was established yet. BMW seem to be quoting a figure that makes no sense.



Surely common sense can be applied in this situation, in that the BMW figures cannot possibly be correct? The highest values I came across (other than BMW's) on that VOSA document on a quick skim were some Ford engines, that can run on 1.09 (16:1). I don't believe BMW are standing over the figure just because the OP received a computer printout from a desk jockey.

From that same VOSA document. It lists the N43 engine as having a lambda value of .7 - 4. I posted it badly on the last page. Voltage of 0.97 to 1.03 = lambda of 0.97 - 1.03 argument is nonsense. Voltage of 0.2 - 0.8 = lambda of 0.97 - 1.03. Only tested one last week on a lambda sensor in a golf.



Would be interesting to know if OP has the N43 or N46 engine

Duke of Speed

the main fail is the co which is over 0.2 the 0.97 to 1.03 is reference to a narrow band sensor the 0.7 to 4 is reference to wideband either way the are all reading to a afr of 14,7 to 16.1 when i set up a standalone ecu i have options to either lambda standards both still only relate to afr as you said 1.09 equals 16 to 1, the 0.7 to 4 is still only reference to the 14.7 to 16 afr

Interslice

The titania sensors in the BMW aren't wideband sensors. From reading about them earlier shey work on the principal of altering a voltage rather then creating one. Your getting them confused.

Duke of Speed

this bmw is reading rich which will give low lambda under 0.97 if the car fuel system was running right the gas analyser in the nct would pass the car bmw state 0.2 co the car is running richer so fault in car if car runs leaner lambda reading will increase and fall into limits thats the simple facts of the situation

Xpro

Any petrol car will operate in closed loop mode at idle conditions, static revs and cruise, which is 1.0V or 14.7 Afr, or near enough. The BMW tech sheet does state that the cars operating voltage will be between 0.7 to 4Volts, but this is not equal to NCT requirements.

In this instance the car is on the rich side just outside the limits. Small limit, but its a fail.
Either a shot sensor, running in default mode of the ecu or some other problem.

You are wasting your time buddy, get you car fixed.