MOT HELP

[Ian F]

Guys,

I need help, my car has just failed its MOT on the Exhaust Emissions test, specifically the Lambda probe. The car is a K 1.8 S/S but has been laid up over the winter. Apparantely the target for the car is 1.09 and I can only get to 1.34, the guy at the Garage tells me this means either I have an air leak or the Lambda''s knackered, either way the car is running too lean. It drives OK and doesn't feel under powered vs normal. Anyone got any suggestions, or have any info on what the lambda limit is from their test results??

 

Many Thanks

 

IAN ☹️

[shn7]

First thing to check is that the correct test is being applied. I'm sure someone will be along shortly who knows the MOt regs. But what they need to know first is the age of your car.

 

 

Steve.

[strongy]

Also take it out for a good blat at high engine speeds to get the catalyst really hot so that it works more efficiently.

 

 

 

Strongy - trying my best to convince 'er indoors that there's no need to sell it

[thinfourth]

or go to a petrol head garage mine should of failed on emissons but it was sorted by a very nice man

 

Blatting round aberdeen wondering wether to buy a jumper or heater

[dino ferrana]

Try finding a garage that puts the probe in a shorter distance "to avoid burning it"

[Ian F]

Thanks Guys, I tried the blat for half an hour and have checked the regs and all is well, I've even tweaked the fuel pressure regulator, if anything its worse than before! Looking at the plugs they are very grey meaning that I'm running very lean, I've also whipped out the lambda probe (I think this could be the problem!) it is also very grey/white, should be black?

 

So, is there any kind soul out there who would mind lending me their K series lambda probe to try and pass the MOT (next Friday), if this works then clearly I will invest in a new probe (£100, ouch). Happy to buy the generous soul a pint.

 

IAN

PS I'm very local to the Wotton Hatch in Surrey (Guildford) *confused*

[Fred]

Ian you are on the right track at the garage we find this fault to be ether a leak or the

probe rover part is i think MHK 10006

 

 

[Glenn Wheeler]

Whats the problem ? I thought these tests were to prevent excess hydrocarbons, if its running very lean does this not mean its a lot cleaner than normal settings ie no soot. I am sure my ignorance will be exposed shortly !

[Nick Woods]

What age is it - pre august 1998 kit built cars only need a visible smoke test (it should say amateur or kit build on the reg document).

 

If it is in this category and they are testing for a catalyst'd car it will never pass. Post 1998 cars have to pass an emissions test regardless of how they were built

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[Roger King]

Glenn,

 

With a catalytic car they don't just test the actual emissions. The car also has to show the correct lambda figure even if emissions are fine. Typically you'd be looking at a range of .98 - 1.02 for a pass on a production car. Lambda 1 equates to a perfect stoichiometric fuel/air ratio which the cat needs in order to reduce oxides of nitrogen. Since oxides of nitrogen tend to very low under light load they can't sensibly be measured directly at MOT time, hence the insistence on a good lambda figure.

 

In any case high hydrocarbons simply indicate poor combustion. This can be caused by being too rich OR too weak (lots of other causes too), so being a bit weak doesn't guarantee low emissions, although it generally does mean a low CO figure.

[Ian F]

Guys,

 

Thanks for all your help, it was a combination of the lambda probe going knackered (apparently they don't like damp garages) and the fuel pressure regulator needing tweaking! Well I'm £300 lighter and CC are better off but at least I'm legal again, just in time for the summer!

Thanks again

 

IAN

 

IAN (got the Green and Yellow Fever!!!)