Emissions problem update.

UK 528 E39. Car failed twice at one testing station for 'Natural Idle Test' CO emissions, at 0.85% Today the car went to my local BMW dealer for a diagnostic check. No faults reported by the ECU. Exhaust system was examined and was OK, so they checked the emissions as per an MOT. All emissions were well within limits. Inc 'The Natural Idle Test', which was 0.50%. A big difference to the fail figure. As nothing was done to the car since it's last failure, I'm beginning to wonder just how reliable the MOT computers are, or is it more likely to be due to the examiner not getting the engine hot enough?. How often are test station computers checked? Mike.

Reply to
Mike G
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it doesn't matter the 0.5 figure is still a fail

Reply to
mrcheerful

Doesnt help the OP, but had a first MOT on the X-trail today- emissions readings were:

Natural Idle Fast Idle. CO: 0.01% 0.00% HC's 3ppm 0ppm Lambda 1.020 1.000

And that was after 2 miles from cold start and 5 mins idling in the workshop- i was quite surprised.

Tim..

Reply to
Tim..

According to the MOT emissions test readout, 0.5% is the max CO allowed for the Natural Idle Test, so that makes it a pass. Just. Mike.

Reply to
Mike G

That is strange as at all the test stations I frequent the figure is to be less than 0.30

Mrcheerful

Reply to
mrcheerful

is it vehicle dependant would older design vehicles have a higher rate

Reply to
Steve Robinson

Dunno. The car is a '96 BMW 528. Sounds like I need to check on the official MOT pass specs for my car. Mike.

Reply to
Mike G

...which you *might* find here:

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Chris

Reply to
Chris Whelan

not actually, because it changes the limits are here: "In-Service Exhaust Emission Standards for Road Vehicles".

and I am certain that a 1996 car must be below 0.30

Mrcheerful

Reply to
mrcheerful

According to Autodata technical data, it says; CO level at idle speed - tailpipe: 0.5 +/- 0.3 CO level at idle speed - sample pipe: 0.7 +/- 0.5 CO content at increased idle speed 0.3

Reply to
redwood

PS, I think Autodata have the decimal point wrong in the +/- figures, I'm guessing it should be 0.03 & 0.05

Reply to
redwood

Mike G ( snipped-for-privacy@lycos.co.uk) gurgled happily, sounding much like they were saying :

There's your answer. How much more of an answer do you need?

Reply to
Adrian

Have you been following the thread?

I'd like a specific answer. IOW the correct CO figure for my car. mrcheerful reckons the figure for my car is a max of 0.30% A main BMW MOT test station reckons it passes with 0.50% or less. The extract quoted says the figure is specified by the vehicle manufacturer. So what is it? 0.30%, 0.50%, or something else?

I'm inclined to believe mrcheerful is right, but at the same time, one would expect a main BMW garage that also does MOT's, (probably testing a larger percentage of BMW's than most test stations) would know the correct figures for my particular car.

I don't know how test computers work. Does the operator simply feed in the details of the vehicle and the test programme does the rest? Or are emission parameters set manually? Mike.

Reply to
Mike G

The manufacturers 'limits' and the MoT limits are not the same thing.

Except in a few specific cases the MoT emission limits are the same for everything since about 1993 (i.e. everything with a cat) and that is:

fast idle test: engine speed within the area of 2500 - 3000 co less than 0,20 hc less than 200ppm

natural idle: between 450 and 1500 rpm co less than 0.30

if the initial generic test fails then the garage will do a specific vehicle test if appropriate, the parameters for which might be slightly different, perhaps a higher fast idle or whatever, but the co is the same.

if the original manufacturer figure is higher than mot limits then the mfr figure is used, in your case the mfr limits come below the mot limits so the mot limits are appropriate.

the book that details it all is: In Service Exhaust Emission Standards for. Road Vehicles' (but I can't find it on the net) Mrcheerful

Reply to
mrcheerful

Doesn't it depend on the car?

Reply to
David Taylor

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