27 replies to this topic

[miniboy1971]

I've got a 2001 (Y plate) Classic Mini Cooper Sport with a JCG S-Works Conversion. I've had the car since new and it's got 44k miles on the clock. This is the first time its failed the MOT and never had a problem before with emissions.

On the two fast idle tests I'm getting CO of 0% and 0% (max 0.3%), HC of 3ppm and 14ppm (max 200ppm), but the Lambda was 1.12 on both occasions (0.95-1.09 max)

The natural idle was OK with CO at 0.16% (0.5% max).

The guy at the MOT station believes it could be either the Lambda sensor itself or the CAT.

They don't have the facility for plugging it into any diagnostic equipment, but there are a couple of places I can take it, but looking at around £ 60 for the privilege.

Is this the only option, could it be anything else ?

If I need a new CAT or Lambda sensor - any recommendations on where's the best place to buy ? Minispares ?

Thanks.

Edited by miniboy1971, 28 February 2009 - 03:23 PM.

[The_Mistro]

i only know a minute amount about the emissions test, but when i took mine in they guy who took it said give the air filter a proper good cleaning out as that has an effect on the readings, dont know which one it effects though, could be worth giving it a clean!

[miniboy1971]

i only know a minute amount about the emissions test, but when i took mine in they guy who took it said give the air filter a proper good cleaning out as that has an effect on the readings, dont know which one it effects though, could be worth giving it a clean!

Thanks for you input...I did think about doing this, but I only changed it 1,500 miles ago (standard one) so didn't bother. I could change it over as the're only a few quid, but don't want to go back to the test place again unless I'm really sure....

[Southy]

I would put my money on both the CAT and Lamba sensor being at fault, the CAT is 7 year old now and will be starting to get blocked up with depositis and causing both the exhaust and engine to get hotter due to it being blocked.

[SimonKnight]

I would say the lambda sensor may be at fault because it may have alot of carbon deposits on it now which is the problem i had, did you get it red hot before the emissions test because that can cause it to be off if its cold

Hope this helps

[miniboy1971]

I would say the lambda sensor may be at fault because it may have alot of carbon deposits on it now which is the problem i had, did you get it red hot before the emissions test because that can cause it to be off if its cold

Hope this helps

Cheers. The car had been running for a while before I took it in and was definitely hot enough. If the sensor is all sooted up, is it worth taking it out for a clean up or is this not going to be good enough ?

[Rosslin Racing]

if you change the oil, plugs and air filter you should get a good reading on the exhaust test it all has an effect on the readings.
if you just poddle around town the lamda my well be coked up in that case take it for a blast!
the oil temp must be at least 80 Degrees for the test as well. you could try cleaning the lamda

Edited by Rosslin Racing, 28 February 2009 - 05:14 PM.

[minidaves]

valve stem seals cause problems on emmsions on these, so a engine flush oil change with proper 20/50 classic oil, air filter and pulgs a splash of injector cleaner and a bit of cat clean and it should go through, i dont normally have an issue getting thes through a mot

dave

[tommy13]

The slightest bolw / air leak in the exhaust system can effect the lambda reading. Block the end of the exhaust and see if it hisses out anywhere.

[syholl]

When you changed the air filter, what type did you put in...?

I'm pretty sure the cooper S Works should have a K&N filter inside the standard housing. This won't be helping if you have put a standard one in.

My sisters Cooper S Sport 5 has failed the emissions test just about every year during the MOT.... Changed the Cat the first time around and this sorted it, then found a more friendly MOT station for future tests. You may need a new Cat if its still the original one...

Sy

[miniboy1971]

The S-works kit only uses the standard air filter and the one that's in there has only done about 1500 miles, but I can change this no problem.

The MOT man said there was a small leak on the exhaust system at the joint between the back box and cat. He thought this could be the problem, so I quickly took the car home (only 200 yrds away) and took it all off and re-assembled it. Took it back to the MOT place, but it made no difference.

I suppose an oil change won't hurt, plus a bit of a flush and the injector/cat clean mentioned.

The plugs are only 1 year old and 1,500 miles old. I cleaned and gapped them the before the test.

I'll give this all a go and see what happens.

Will BOSCH diagnostic equipment be any use on a Mini ?

[minidaves]

take it for a good 20mile blast in 3rd gear at 4000rpm or so, it needs a clean up and needs to get hot.

where are you a plug in for dianostics i charge £25 and can do exhaust check

dave

[miniboy1971]

take it for a good 20mile blast in 3rd gear at 4000rpm or so, it needs a clean up and needs to get hot.

where are you a plug in for dianostics i charge £25 and can do exhaust check

dave

Thanks for the offer, but I live nr. Maidstone in Kent !! A bit too far me thinks !!!

Can't drive it anywhere now as the tax has run out...kicking myself !!!

[miniboy1971]

minidaves - I've PM'd you as well. Maybe we can work out some arrangement for you to come and help with the diagnostics ? Cheers.

[Sprocket]

Crap crap all crap except these

The slightest bolw / air leak in the exhaust system can effect the lambda reading. Block the end of the exhaust and see if it hisses out anywhere.

take it for a good 20mile blast in 3rd gear at 4000rpm or so, it needs a clean up and needs to get hot.

where are you a plug in for dianostics i charge £25 and can do exhaust check

dave

This is the imortant bit!! "There is nothing wrong with the cat!!" and by all acounts the engine is running as it should be.

The problem is that there is an excess of oxygen at the tail pipe, NOTE! 'tail pipe' the MOT machine does not care from where the oxygen has come from. The CO is zero because the cat has converted/ reduced it, the HC's are low because the cat has converted it, the cat is functioning

I strongly suspect your exhaust is leaking at some point AFTER the lambda sensor It does not take much for it to become a broblem.

Or the engine is running lean.

The only real advice I can give is to find a decent garage that has a four gas analyser. This will give you CO%, HC ppm, O2 % and CO2. While the test is being carried out, a diagnostic should be used to determine if the Lambda sensor is functioning as it should. You can check this yourself, but its by no means a simple task. If the Lambda sensor is functioning, the problem is a leaky exhaust!