N53 330i MOT Emissions

RichJ · 05-07-2011, 09:16 AM

Recently had an MOT (it passed!) and the emissions lambda value is near the max limit of 2.3. Mine was 2.21. Is this normal as the range is between 0.97 - 2.3? Any thoughts?

doughboy · 05-07-2011, 03:38 PM

I thought the standard limits for the BET were 0.97 - 1.03?

i.e + or - 3% either way on the ideal 'perfect' lambda figure of 1. (=fuel air ratio of 14:1)

JonnySi · 05-08-2011, 06:47 AM

Its because the N53 direct injection engine runs so lean that it actually produces other harmful emissions. One of these is NOx, which is mainly emmited from diesels. A petrol MOT gas meter will see this as a fail because the CO is also too high. By driving the vehicle hard, the engine changes and runs in homogenous charge mode (like a normal petrol) and these harmful emissions drop and pass the MOT.

I posted this reply in the E93 MOT fail thread.

RichJ · 05-08-2011, 06:57 AM

The MOT pass values are as above and this is 1 above the N52.

doughboy · 05-08-2011, 07:19 AM

As said, it must be a special lambda figure for your engine, that's why your engine is near the limit as the limit is probably set for your engine or others like it.

The 335i is DI but that still has the MOT lamda 0.97 - 1.03 range.

If its in its in. Don't worry about it.

05-07-2011, 09:16 AM	#1
RichJ First Lieutenant 10 Rep 358 Posts Drives: E92 M-Sport 330i Le Mans Blue Join Date: Jan 2010 Location: South iTrader: (0)	N53 330i MOT Emissions Recently had an MOT (it passed!) and the emissions lambda value is near the max limit of 2.3. Mine was 2.21. Is this normal as the range is between 0.97 - 2.3? Any thoughts?
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05-07-2011, 03:38 PM	#2
doughboy Major General 1545 Rep 8,970 Posts Drives: 2018 M2 Comp 6MT Join Date: Jan 2009 Location: UK iTrader: (2)	I thought the standard limits for the BET were 0.97 - 1.03? i.e + or - 3% either way on the ideal 'perfect' lambda figure of 1. (=fuel air ratio of 14:1) Last edited by doughboy; 05-07-2011 at 05:28 PM..
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05-08-2011, 06:47 AM	#3
JonnySi BMW Technician 6 Rep 197 Posts Drives: BMW Join Date: Jun 2010 Location: England iTrader: (0)	Its because the N53 direct injection engine runs so lean that it actually produces other harmful emissions. One of these is NOx, which is mainly emmited from diesels. A petrol MOT gas meter will see this as a fail because the CO is also too high. By driving the vehicle hard, the engine changes and runs in homogenous charge mode (like a normal petrol) and these harmful emissions drop and pass the MOT. I posted this reply in the E93 MOT fail thread.
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05-08-2011, 06:57 AM	#4
RichJ First Lieutenant 10 Rep 358 Posts Drives: E92 M-Sport 330i Le Mans Blue Join Date: Jan 2010 Location: South iTrader: (0)	The MOT pass values are as above and this is 1 above the N52.
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05-08-2011, 07:19 AM	#5
doughboy Major General 1545 Rep 8,970 Posts Drives: 2018 M2 Comp 6MT Join Date: Jan 2009 Location: UK iTrader: (2)	As said, it must be a special lambda figure for your engine, that's why your engine is near the limit as the limit is probably set for your engine or others like it. The 335i is DI but that still has the MOT lamda 0.97 - 1.03 range. If its in its in. Don't worry about it.
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