Fiesta MOT Emissions Failure

[Dustyy]

My trusty load lugging Fiesta ('92 K reg 1.1, 79k) has stumbled at the MOT emissions test on carbon monoxide. the limit I believe is 0.3% but the Fiesta was pumping out 5%
Can anyone offer any advice on where to start looking on rectifying the situation? I have looked at the air filter and it looked ok, spark plugs looked as though there was excessive carbonation and the oil cap/breather looked a bit clogged up.
The car is booked into a garage shortly, but anything i can do myself would be a help and may be i can understand the reasons why a little better

Thanks

 

[Diyisfun]

Took my car for MOT recently, kept failing on emissions, the guy left it revving for quite a while, rechecked it passed. He said it often happens if you dont do many miles & at high revs. Do you only use yours for short journeys if you do might be worth taking it for run at high revs prior to next MOT.

 

[lewy]

to get my Shogun through the MOT I have to drive it hard for 5 mins then take it straight in and do the emissions test first to get it to pass.

I used to have a Fiesta, do the normal stuff i.e. air filter, re gap the plugs. If it's yellow gunk coming from the breather hose from the oil filling cap try and get it all out but if you can't, the part is only about a fiver from the dealer (it's like a mesh, you can't remove it but can bang it about to get some crud out).

If it's high on the HC reading then you may need a de-coke, which means take the head off and clean it up and re-grind the valve seats.

 

[Dustyy]

Thanks for your input.
The car has a daily 40 mile roundtrip commute on the motorway so it gets a good workout each day. I also gave it a good run before taking it in for the MOT.
During the MOT they gave it a good revving to try and get it through, but alas no joy.
I think i will get the cap changed, filter etc and see if that helps.
Will re-gaping the spark plugs help then? What does that do?

 

[Hitachimad]

You could try putting some 'Redex' down the bores, then take it for a roasting on the motorway.

 

[voicey]

My local friendly MOT place used to remove the air filter to get cars through the emission test - might be worth a try!

 

[Quick Fit]

To be honest if the emissions was 5% changing the filer and cap plus plugs won’t make that much difference.
The chances are it’s running to rich or burning too much oil. There are other possibilities that can hinder the emissions. ( Cat is one ) if one is fitted.
QF

 

[Dustyy]

If its running too rich that should be something the garage can sort out isn't it? Though burning oil could be an indication of worse problems?? The car is worth peanuts so not looking to spend much on it, but if its a simple(ish) thing to sort out then I'll stick with her.........

 

[chainsaw_masochist]

If it was a question of altering the mixture to try to get the carbon monoxide down to an acceptable level I think the mot garage would have done that (unless they conduct tests only ie do not do maintenance). You could try replacing the air-filter but that is unlikely to account for the 5% CO reading. So it’s likely to be something else, though hopefully not serious.

Try to do what you can before reaching for the wallet. Are you actually using oil? Has there been a noticeable deterioration in economy? Take out the plugs and have a look as to what condition they are in. If they look dry and healthy it would lessen the likelihood of an oil-related issue. Check the gaps as recommended.

If you are getting blue smoke out of the exhaust this could point to valve stem seal wear and would increase carbon monoxide readings. I understand seal wear to be quite common with smaller Ford engines. Replacement seals would not be particularly expensive but obviously the head would have to be removed so you would have to consider the labour costs.

If on the other hand the plugs look oily you might be wise to consider having a compression test. Oily plugs can be indicative of piston-ring wear and this could be determined with a ct. Has the oil warning light been coming on at all? It is possible that you could have ring wear and this could affect the CO reading. This would really be engine rebuild time and would probably be better to count your losses and kiss the car goodbye.

Good luck with your endeavours.

 

[Dustyy]

Thanks Chainsaw,
The mot station is a council run jobby (no vested interests in shafting me for some 'welding' or suchlike!!), so they don't really do any adjustments during the test.
Its booked in a local place which they recommended to see if they can tweak it to get past the emissions so hopefully they can do something with it.
It uses a bit of oil, but nothing excessive i don't think. The plugs were all dry, perhaps a little carbonation which the Haynes manual says can indicate a too rich fuel mix.
79k doesn't seem like a huge mileage, but i s'pose when the axe comes, it comes

 

[chainsaw_masochist]

A bit of a ‘tweak’ required if it's to satisfy the emissions; it’s reading is about 1,500% beyond the acceptable level after all. If you have noticed a marked deterioration in economy recently then this could denote that the mixture should be reset.

If the plugs are dry that’s good, so I reckon you can eliminate anything major. Is the engine carburettor fed or injected by the way?.

 

[Dustyy]

i'm no expert, but i would say carb fed. Its the most basic of basic 1.1LX.
Economy isn't great for such a small engine so fingers crossed that its running too rich ....

 

[Steve]

i took my punto for its 1st MOT (3years old) on 26000 miles, had ben told by the dealers 6 months earlier that it had just had a service. Failed MOT on emissions. Guy sez, dissaprovingly, when did it last have a service? i sez "6 months ago" he sez "no way". Anyway, cost me £20 for 1st MOT, then £99 for full service and someone to rub copper grease everywhere under the bonnet, 2nd check MOT passed, but i wasnt charged. I think there are rules that if the problem is remedied at the same place they cannot charge you for 2nd MOT. I would always reccomend the small garages. Fiat place quoted me £19 for MOT, but i thought, where they gonna make their money on that? They would have charged £hundreds for a service so it would pass!

 

[Dustyy]

Turns out the lambda sensor was covered in gunk and wasn't heating up properly. Throw in a bit of engine cleaner type stuff and jobs a good-un. CO readings now <0.3%
Going back for the MOT next Monday so fingers crossed all should be ok.
Thanks for everyone's input and BTW, does anyone know how the front valance on the fiesta attaches to the car? I need to replace it, but without taking off the bumper its hard to see how its attached - welded (job i can't do) or bolted (job I can do)
Cheers

 

[Dustyy]

Wa-hooo, the fiesta lives on for another 12 months!!
Passed the emissions with flying colours!