Hi Guys,

Just need a bit of advice as Massively failed on my emissions today, It is a '98 1.8 Escort GTi with a 2.0 Zetec engine. Results below:

Fast Idle:

CO 2.064% (upto 0.300%) Fail
HC 81ppm (Upto 200ppm) Pass
Lambda 0.949 (0.95-1.09) Fail

Secomd Fast Idle:

CO 2.371% Fail
HC 80ppm Pass
Lambda 0.940 Fail

Natural Idle

CO 0.367% (Upto 500%) Pass.

It was fine last year and the only difference is that it has had a new headgasket and now has a drilled airbox.

Any suggestions please help.

 

As it's way out I would guess at lamba sensor

 

I would say that it has an air leak somewhere. The lambda being 0.949 says it is is running slightly too lean (if I remember correctly, if not, someone will).

 

what temp was the oil?
9 times out of 10 the cat isnt hot enough.

 

I always thought

1.00 Lambda = 14.7 A/F ratio = Desired reading

0.97 (or less) - 1.00 Lambda reading = Rich

1.00 - 1.03 (or higher) Lambda reading = Lean

Can anyone clarify ?

 

Just done a bit of Googling

14.7 : 1 = Desired mixture (14.7 ltrs of air to 1 litre Fuel)

Lambda = 1.00 for desired mixture

So 14.7 x 1.00 = Desired mixture of 14.7

Lambda reading of 0.97 gives a mixture reading of 0.97 x 14.7 = 14.26 (14.26 litres of air to 1 litre of fuel) so a slightly richer mixture

Lambda of 1.10 - 1.10 x 14.7 = 16.7 (16.7 litres of air to 1 litre of fuel) Weak

 

So effectively my car is running massively rich?

 

Give it a good drive and check to see if you can smell the cat, when was your car services last dude,also just check your oil too incase your burning some too, normally I'f it rich the lamda reads low, sounds like it needs a good drive

 

Last services two months ago, but I use it every day including a nice motorway stretch, not burning Any oil though.

 

I'd say Lambda sensor.

The correct air fuel ratio is 14.7 to 1, that's 14.7 kg of air to 1 kg of fuel, it works by weight not volume.

 

Well someone needs to tell petrol stations as I buy my petrol in litres

 

That's OK because your injectors measure the fuel by time. As long as the resultant mixture is correct it's really only nitpicking what measurements are used.

 

You can buy pattern cats for £90 and the lambda should be no more than about £20/30 so try that first.
Could be anything that's caused it to fail,they dont last forever on some cars,particularly fords.

 

dont change stuff willy nilly, get a diagnostic done then you will KNOW which component is faulty!