Hi there, 

This is my first post, and i was hoping for some advice.

I bought a mk2 1.8 duratec focus, it failed on emissions on all fronts at idle amd fast idle. I have attached the faikure slip as a pic.

I have changed the maf, lambda, air filter, sparks, oil and filter - retested and still failed! 😞

However i wondered if the thermostat would cause the problem. The test menu says engine temp after standard driving of around 117c and the coolant temp appears to be between 60c and 70c. 

Any thoughts would be welcomed.

Thanks david

can you post up the actual emmisions sheet . 

 

1 hour ago, Dave_uk101 said:

I have changed the maf, lambda, air filter, sparks, oil and filter - retested and still failed!

There are usually two O2 sensors, on this engine I think one is called the CMS (Catalyst Monitoring Sensor). One will be each side of the Cat.

Exhaust leaks can cause emissions failures, they let air in which confuses the O2 sensors. Then I guess cat is the next most likely cause.

It sounds rather more than can be expected from a thermostat problem. I am not sure  why the test menu & coolant temp differ, there is only one engine / coolant temp. sensor. The gauge on the dash is sometimes set up to lie, I have heard. Strapping a temperature sensor (like a meat probe) to the rubber hose to the radiator, then wrapping some cotton fabric round the pair can give a reasonable measurement of the water temperature going to the radiator. I have thermisitors mounted on rubber hoses like that, they seem to be within 2-3 deg of the expected readings.

There is apparently a temperature sensor in the thermostat housing that can fail and cause rich running and extended cranking, but won't affect the temp gauge. If you can get hold of a scantool it might be worth checking live data for the temp sensors and seeing if they're showing sensible values, as changing it on the off chance is a bit of a pain. 

Mot fail details added...

Just checked the cat, without the car running. All looks fine.

Its a real killer, not sure what else to check to sort the high emissions.

Not sure how you're visually testing the cats effectiveness lol...

Does it burn oil or smoke at all?  Looks like it's either burning oil or overfuelling quite badly.  

Also you mentioned the 'dash test' in the first post, that always shows 40c higher than the guage so there's no problem there.

It doesnt seem to smoke although it does seem to leave a oily/wet mark on the ground if increase the rpm while stationary.

I checked the cat for holes to make sure it wasnt allowing air to be sucked in and effect the post cat lambda.

All ears to any suggestions.

How would you check if the cat is past its best? 

Ps. I am fairly sure its overfuelling. But not sure what is left to check...

41 minutes ago, TomsFocus said:

Not sure how you're visually testing the cats effectiveness lol...

Does it burn oil or smoke at all?  Looks like it's either burning oil or overfuelling quite badly.  

Also you mentioned the 'dash test' in the first post, that always shows 40c higher than the guage so there's no problem there.

you beat me , i was thinking oil burning too, as it is a 1.8 duratec and they burn oil . i had one at work that failed emmisions due to burning oil, customer didnt realise or notice any smoke. 

What was the fault? Piston rings?

yep. ended up putting a recon engine in, then it passed  emmisions no problem. 

years ago I had an escort (car not female). Failed on emissions. Diagnostic check done at garage, he showed me the live data with the engine running. this showed how long the fuel injectors were opening on each cycle, he said it is far too long and should be more like .. (can't remember the figures). He then checked live data from oxygen sensor and said voltage from it was totally out and he said most likely the a faulty oxygen sensor was causing the overfueling.  I replaced the sensor and then it was fine.

I know you have replaced the sensor, but the point is, if you want to know if it is overfueling or an oil burning problem perhaps you need to see the live data to see how long the fuel injectors are opening for and check if it is out of spec. I do not know if cheap easily obtainable fault code readers and free software like Forscan can show the fuel injector opening times or if it needs some special kit that only a garage would have.

Hopefully some other readers of this can tell you if Forscan or other free software in conjunction with a cheap OSBD port reader can tell you if it will show the injector opening times and what they ought to be

I can imagine you feel gutted at present

On 5/18/2018 at 2:26 PM, isetta said:

years ago I had an escort (car not female).

Lambda = 0.89 and 0.86 show that it is running very rich. This would indicate a problem with the pre-cat lambda sensor or the wiring connections to it (rusty connectors, poor earth?). It could be the ECU, but more likely wiring or sensor.