High CO on daughter's Fester. MOT shock horror

[susser]

My daughter's Fiesta 1.25 Zetec SE (2000), has failed MOT on hHigh CO. 1.09%

HC is 118, CO2 is 14.23, O2 is 0.15, LAMBDA 0.97.

 

Seems to me that it needs more O2, I guess the lambda probe should see the lack of O2 in the exhaust and weaken the mixture off. So is the probe 8u66ered (we had a new one last year), or can we get it mapped to run leaner ?

 

Or am I barking up the wrong tree.

 

Paul

(1/2 🙆🏻ed industrial combustion technologist)

[shn7]

Is the air filter clogged? I doubt it'll be re-mappable without fitting an Emerald 😬

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[susser]

Steve

I had wondered about the AF;

It's pretty clean, but not spotless. I would have thought tht the Lambda probe would have compensated for that and remapped or done whatever it's supposed to.

"Fitting an Emerald" may be a solution, I suppose, if it comes to the crunch.

[k80rum]

Might also be worth checking that no spark plugs are loose. I had a Clio fail an emissions check a few years back and this turned out to be the culprit for a high (I think..) CO reading. It's a quick and easy check at the very least.

 

Darren E

 

K80RUM Website and Emerald maps library

 

Superlight R #54

 

 

[susser]

Hmmmmmmmmmm

Plug leads are all OK and it's running fine.

I think part of the problem is the large amount of oil it burns; It does about 150 miles between the top and bottom marks on the dipstick

I wonder if all the ash or carbon from that oil is doing the sensor

[shn7]

That much oil use doesn't sound good. Sounds like the internals must be pretty kn***ered.

 

The reason I asked about the AF was because I've had a tickover problem on an MX5 we bought caused purely by a very very dirty AF. Doesn't sound like your's is anywhere near as bad so look for other reasons. The oil use could be it but I'm no expert.

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[Unclefester]

You called?

 

Lucy in the Sky with Diamonds..ooooh hooo hooo!!...

😬 😬Abbey Road Time-Machine *eek*

 

[shn7]

Wondered how long that would take 😬

 

Steve.

Sussex (West) AR

Not forgetting Percy the Polar Bear

[Unclefester]

Yerm. My powers of observation are at an alltime low.....

 

Lucy in the Sky with Diamonds..ooooh hooo hooo!!...

😬 😬Abbey Road Time-Machine *eek*

 

[LesG]

You need to get the fester on a diagnostic scanner somewhere; then run a functional test on the O2 sensor to see whether it's switching on and off as it should (particularly as you rev the engine). Also check the wiring to it before condemning it.

I assume the cat is in good condition? If it's the original one; sort of great-but it's getting on a bit now; if it's had a 'cheap' replacement-bin it and buy a new genuine one, that'll probably solve your problem.

[Klunk]

I have to agree with the other guys - that much oil doesn't sound good ☹️

 

However, I have a quick and easy suggestion which worked on an old Nova Sport of mine (was I speaking out loud just then? 😳 ). Take off the crankcase breather pipe from where it connects back to the inlet manifold. Block the hole in the manifold and route the crankcase breather to some form catch tank which in the case of my Nova, was an old half litre oil bottle tie wrapped to the hose 😬 - Passed two MOTs like that before I eventually got rid.

 

Regards ,

 

Giles

[susser]

Steve; It's not knackered. When we had a failed valve a few weeks ago, I got 150psi on all cyls (except for the 3 on the failed onehere ). One thing is the bores etc. I think the car's been used for tootling about for it's 74,000 miles. The bores have a brown tinge to them. We've given the car a number of 100 mile runs at dual carriageway kind of pace and the oil consumption has reduced. The trouble is, that it increases again due to the short (2x10 mile) trips that it gets daily.

Maybe Les's idea of getting it diagnostic-ed is the way. Trouble is, I don't usually let garages anywhere near my cars. They haven't generally impressed and if you've got enough time, I'll tell you tales that will curl your spanners up. I've got an oscilloscope that ought to tell me what it's outputting.

With the compressions up in the 150psi, I don't think the problem is blow by, more like lack of oil control.

Looking at the full set of numbers, I've an idea that the Lambda probe is giving the wrong output and allowing overfuelling slightly. There's not much O2 left to complete combustion. If I gave it a good hard run and got the Lambda probe hot, then it ought to get clean. I can't see how a Cat can turn CO into CO2 unless it's got some oxygen to do it with. There isn't a lot at 0.15% is there.?

The other way might be to drag the car into the road and set fire to it. It's come pretty close to that more than once.

I'll go and have another drinkie now and see if that helps me eeeerrrrrrrrrrrrrrrrrrr,

 

[TJG]

CO high, HC good. Can't give more O2. Suspect Lambda sensor or cat, neither like excessive oil consumption. Loose plug probably high Lambda. Could do basic check on Lambda sensor with bar graph on multimeter. Well worth a good hard blat before retest. No expert, just my opinion.

[TJG]

Susser, still triping when you posted again. Going now

[susser]

TJG

I'm thinking like you. but, what could a cat do to correct high CO unless it's also got O2.

Kinda comes down to the Lambda again.

On Ploy that springs to mind is;

Buy new probe for MOT, replace with the old one after and "wrap it in cotton wool". Put it in again for next year. Have sleepless nights about ruining the planet, sell the Caterham and buy a Pious.

 

[TJG]

IIRC high CO results in low O2. Therefore anything, AMM, coolant sensor etc could have an effect. As it runs ok otherwise I would still think lambda/cat. Spare probe for MOT only if it cures it seems like a good plan. As for the Prius................