Jump to content


Photo

Emissions Fail


  • Please log in to reply
24 replies to this topic

#1 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 16 March 2020 - 03:15 PM

Mini failed the MOT today. yes you guessed it emissions, it always just squeaked through at the old garage I used to take it to, but they have closed and the place I have taken it has failed it. (I don't blame them by the way) they can only do what the analyser tells them. so its a 1995 cooper spi, I had fitted a new cat before the MOT,the last garage recommended that, fairly confident the  Lambada sensor is working correctly, it was when I plugged it in the code reader thing a few weeks ago. it failed on exhaust carbon monoxide content after 2nd fast idle. showing 1.240 on the fail sheet and second fast idle  0.855. I am sure this has been done a zillion times, any recommendations or ideas where I can start to rectify this. I did take it out for a 2hour drive before the MOT so Italian tune up made no difference. Thanks in advance of ideas. it has had new vac lines etc before the last mot, and new elbows etc so confident they are all good.


Edited by ClassicAsh, 16 March 2020 - 03:20 PM.


#2 pete l

pete l

    One Carb Or Two?

  • TMF+ Member
  • PipPipPipPipPipPipPip
  • 1,068 posts
  • Location: East of France

Posted 16 March 2020 - 03:17 PM

Following. My MPI failed at 3.0

 

I was told to put a GOOD new cat on it, never did, took it apart to restore.



#3 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 16 March 2020 - 03:21 PM

Following. My MPI failed at 3.0

 

I was told to put a GOOD new cat on it, never did, took it apart to restore.

yeah I put a new CAT on if a few weeks ago, so pretty sure that's ok, but thanks



#4 r3k1355

r3k1355

    Super Mini Mad

  • Members
  • PipPipPipPipPipPip
  • 577 posts
  • Local Club: East Anglia

Posted 16 March 2020 - 03:40 PM

Load up the parts cannon.

 

New lambda, new CTS, clean&rebuild or replace the injector, new injector seals/rubbers.


Edited by r3k1355, 16 March 2020 - 03:40 PM.


#5 xrocketengineer

xrocketengineer

    Rocket Man

  • Members
  • PipPipPipPipPipPipPip
  • 1,485 posts
  • Location: Florida, USA

Posted 16 March 2020 - 04:00 PM

I would carefully look at the manifold to downpipe joint with the three studs/nuts are. Look for any evidence of soot on the outside. If there are any leaks, the O2 sensor readings will be affected. The correct fix for this would be to get the new gasket, studs and nuts (Minispares has them) and replace them. I would apply Permatex 80335 or equivalent to the gasket to ensure the seal. It contains Sodium Silicate which is safe for the catalyst and turns into glass when it cures with the heat.  RTV sealers can damage the catalyst.      

If you are in a hurry, you could try applying the Sodium Silicate on the outside of the leak as a temporary fix to see if it seals.  



#6 MatthewsDad

MatthewsDad

    Speeding Along Now

  • TMF+ Member
  • PipPipPipPipPip
  • 417 posts
  • Location: Warrington

Posted 16 March 2020 - 07:15 PM

You might already have seen it but the link below is always a good starting point. A lot to go through, but your problem could be a combination of factors conspiring against you.

http://www.theminifo...njection/page-2

#7 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 17 March 2020 - 01:47 PM

ok so spent the morning checking the obvious, all the pipes and elbows, all connections etc all look as good as new and they have only been on 12 months or so.  checked manifold and that gaskets is fine and no leaks.I have plugged the code reader in (sykes pickavant) No fault codes show up and component test as follows

 

Engine speed -1050 slight fluctuations 980 to 1050

Idle- switch open

p/n- switch open

map sensor- 027 -029

coolant temp - after running for 20 mins 86 -88 C

air temp - 23C

ambient temp- 200C

batt voltage -13.7

throttle pot - 0.62 to 4.00 volts ignition off nice and smooth

lambda sensor - 0.1 to 1.5 fluctuating

I think all these reading seem ok and according to the code reader manual all are good. So given that I have checked most things visually and see nothing wrong and code reader says fine.... where should I start?...… apart form selling the sodding thing. lol...

 


Edited by ClassicAsh, 17 March 2020 - 01:49 PM.


#8 rich_959

rich_959

    Super Mini Mad

  • TMF+ Member
  • PipPipPipPipPipPip
  • 515 posts
  • Location: East Yorks

Posted 17 March 2020 - 02:10 PM

The Cat? It's 'downwind' of all the data you get from above. I know you said you replaced it, but I've heard of cars failing on new Cat's. Where was it from? 

 

Have you tried a good old fashioned Italian tune-up prior to testing?



#9 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 17 March 2020 - 02:20 PM

The Cat? It's 'downwind' of all the data you get from above. I know you said you replaced it, but I've heard of cars failing on new Cat's. Where was it from? 

 

Have you tried a good old fashioned Italian tune-up prior to testing?

the cat was a reputable company buy, so I think it should be ok, Yeah I did take it out for two hours before the test along the a14 at 70mph so Italian tune up let me down this time!



#10 xrocketengineer

xrocketengineer

    Rocket Man

  • Members
  • PipPipPipPipPipPipPip
  • 1,485 posts
  • Location: Florida, USA

Posted 17 March 2020 - 03:40 PM

The lambda sensor reading looks funny. As far as I know the maximum voltage has to be less than 1 volt for a narrow band sensor. It should be around 0.1 volts for lean, 0.45 for stoichiometric and 0.9 volts for rich. The sensor acts as a battery generating the voltage and it can not more than 1 volt. 

Wide band sensors need a voltage applied to them and act as a variable resistor changing the output voltage in proportion to the mixture. Modern cars use these.

 

 https://www.engineba...tio Basics.html



#11 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 17 March 2020 - 03:48 PM

The lambda sensor reading looks funny. As far as I know the maximum voltage has to be less than 1 volt for a narrow band sensor. It should be around 0.1 volts for lean, 0.45 for stoichiometric and 0.9 volts for rich. The sensor acts as a battery generating the voltage and it can not more than 1 volt. 

Wide band sensors need a voltage applied to them and act as a variable resistor changing the output voltage in proportion to the mixture. Modern cars use these.

 

 https://www.engineba...tio Basics.html

the reading for the sensor is defiantly 0.1 -1.5 fluctuating up through the numbers. to be honest the rest of your comments baffled me lol, thats down to me not you though. what would this suggest then a knackred lambda sensor or something else? thanks



#12 Squipper

Squipper

    Passed Test

  • Noobies
  • PipPip
  • 33 posts
  • Location: Ipswich

Posted 17 March 2020 - 06:47 PM

Hi

 

Get it MOT'd at a different place and see if the results are the same, first test might have been a duff one :ohno:



#13 xrocketengineer

xrocketengineer

    Rocket Man

  • Members
  • PipPipPipPipPipPipPip
  • 1,485 posts
  • Location: Florida, USA

Posted 17 March 2020 - 10:26 PM

Hi

 

Get it MOT'd at a different place and see if the results are the same, first test might have been a duff one :ohno:

That might be the best next alternative.

 

Sorry about the confusion. What I meant was the Mini has the narrow band O2 sensor. It operates along the blue line  on the figure. The sensor is not very smart. It can tell that mixture is lean producing low voltage (0.1volts), Ideal fuel ratio (stoichiometric) of 14.7 to 1 (0.45 - 0.5 volts) or the mixture is rich (0.9 volts).  As you can see in the figure, it is not possible to read a specific value of air/fuel ratio other than 14.7 to 1 since the voltage  does not vary linearly with the A/F ratio. The sensor can not generate more that 1 volt when operating properly.

 

The wide band sensor (red line) output voltage on modern cars has a corresponding voltage for a any specific A/F ratio. 

 

I am not going to tell you to replace the O2 sensor but I think that you need to discuss the 1.5 volt reading with an experienced mechanic. I replaced an O2 sensor on my 2008 Nissan truck a few years ago and I vaguely remember it reading over 1 volt. However in this case my truck being a V8 had four sensors.  Two were air/fuel ratio sensors (wide band) to control the mixture upstream of the catalysts and the other two were narrow band to check downstream that the catalyst was working properly. The detected failure code, if the sensor had been working properly, was that the catalyst was bad and it meant replacing the catalyst and exhaust manifold. However the truck had (and still has) very low mileage and it did not make sense to replace all that. I bought a new Bosch sensor and the problem went away. This narrow band sensors last 30 to 50 thousand miles and apparently age is an issue too. So, my take is that the O2 sensor is bad, but get a second opinion.           

 

AF%20Basics%203.gif


Edited by xrocketengineer, 18 March 2020 - 12:11 AM.


#14 ClassicAsh

ClassicAsh

    Mini Mad

  • Noobies
  • PipPipPipPip
  • 126 posts
  • Location: Northamptonshire

Posted 18 March 2020 - 07:03 AM

 

Hi

 

Get it MOT'd at a different place and see if the results are the same, first test might have been a duff one :ohno:

That might be the best next alternative.

 

Sorry about the confusion. What I meant was the Mini has the narrow band O2 sensor. It operates along the blue line  on the figure. The sensor is not very smart. It can tell that mixture is lean producing low voltage (0.1volts), Ideal fuel ratio (stoichiometric) of 14.7 to 1 (0.45 - 0.5 volts) or the mixture is rich (0.9 volts).  As you can see in the figure, it is not possible to read a specific value of air/fuel ratio other than 14.7 to 1 since the voltage  does not vary linearly with the A/F ratio. The sensor can not generate more that 1 volt when operating properly.

 

The wide band sensor (red line) output voltage on modern cars has a corresponding voltage for a any specific A/F ratio. 

 

I am not going to tell you to replace the O2 sensor but I think that you need to discuss the 1.5 volt reading with an experienced mechanic. I replaced an O2 sensor on my 2008 Nissan truck a few years ago and I vaguely remember it reading over 1 volt. However in this case my truck being a V8 had four sensors.  Two were air/fuel ratio sensors (wide band) to control the mixture upstream of the catalysts and the other two were narrow band to check downstream that the catalyst was working properly. The detected failure code, if the sensor had been working properly, was that the catalyst was bad and it meant replacing the catalyst and exhaust manifold. However the truck had (and still has) very low mileage and it did not make sense to replace all that. I bought a new Bosch sensor and the problem went away. This narrow band sensors last 30 to 50 thousand miles and apparently age is an issue too. So, my take is that the O2 sensor is bad, but get a second opinion.           

 

AF%20Basics%203.gif

 

I have a new genuine Lambda sensor (well a bosch one) that I never fitted when I restored the car, so might as well fit it and see if it makes a difference to the readings, if that fails its going to be sorn time, and head scratch until the mass panic is over, scratch my head, wash my hands and have a think about it. thanks for the help.



#15 mina08

mina08

    Mini Mad

  • TMF+ Member
  • PipPipPipPip
  • 244 posts
  • Location: Stockholm

Posted 18 March 2020 - 12:39 PM

i was having the same problem, i moved my lambda down the exhaust off the manifold as it only reads from one pipe, so now its after the manifold, it passed






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares