Mondeo MOT fail on Emission

Would help if you could give us the actual readings, age of the car and the mileage, and any other running faults.

Check the O2 sensor multiplug thats strapped to the rad for corroded contacts and water ingress (common), the heater vacuum take off elbow behind the coil pack for splits, the AMM multiplug, and any exhaust leaks pre or post cat.

Tim..

Could be a lot of different things. How has your oil consumption been? Something simple like a clogged crankcase breather can cause excess oil consumption. Valve seals also increase oil consumption at higher RPM.

Since the car does not seem to be misfiring, the electrical system is probably OK. You have probably checked obvious things like a really dirty air filter. The air mass meter would make the mixture too lean if anything so and I doubt if it would effect high RPM operation much.

Are you _sure_ the Cat is OK? A hot cat should strip out all the nasties.

As someone else pointed out, all the data would be handy. High CO points to a dead cat BTW.

Pete.

Yes and no, a healthy management system, engine and o2 sensor but a dead cat should give tailpipe readings of around 1-2% CO and less than 200ppm HC- i.e. that of an engine without a cat. For you to have 8% CO something is wrong, whether the cat is working or not.

One thing I forgot to mention in last post- is the engine warming up to full temperature- temp gauge should be at 12 o'clock?

Tim..

Too lean? Surely 8% CO would give a low O2 reading as well? If the fuel's not being converted to CO2, that would imply there's not enough O2 in the system (or there's too much fuel - same result from different direction).

Very dirty air filter, blockage in the airways, leaky injector?

What effect would having an air-leak upwind of the O2 sensor do? It would make the ECU think the engine was running lean, so up the fuelling.

Can't a blocked crankcase breather give high CO too? Has the car had fresh oil & filter recently?

And a bit of an Italian tune may not hurt either ;-) I try to give mine a

40 mile blast once a week just to heat the oil up. I used to drive 500 miles a week. If I didn't take the car out once a week now (on necessary business) the poor thing probably wouldn't get used week to week!

Pete.

Thanks to all those who replied. It was the map sensor at fault. Now (expensively) fixed and MOTd

cheers

Mike