Hi
I have a 1.6 zetec se petrol which failed mot on emmissions, its had a new breather pipe and lamda sensor which have made no difference. I was told it is burning oil a bit so could be the cat also read the ecu could be at fault. any help on this? When revved up to 3000rpm its a bit up and down instead of constant so they cannot get an accurate reading.

 

worn pistons/valves??

 

Have you got any readings from the emissions?
CO, CO2, O2, HC, Lambda value?

 

Could coil pack cause high emissions? Any lights on on dash

 

Could be anything. Base engine fault causing the smoking.

As oldford has posted, need to see the results from the emission test really.

Get fault codes read, lambda sensor values checking on live data for a start.

I had a car (mk3 Golf GTI) fail with very high emissions (10% CO) turned out the fuel return to the tank was blocked and the fuel pressure was 6 bar.

 

Could do if it's misfiring!

 

The hunting ("a bit up and down instead of constant") could be caused by an air leak on the inlet (after the throttle body, before the manifold meets the head). This could affect the emissions....!

With the engine ticking over get yer head under the bonnet and listen for a hissing noise, if you think you hear one spray some wd40 around where you think the noise might be and see if this affects how the engines ticking over.

Just an idea, hope it helps!