Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - Ross Nicolai

This weekend the car went in for its MOT and low and behold it failed on emissions by a very large amount. CO was 10x what it should be at 2.20% and Hydrocarbons were more than double at 500ppm. This was kind of expected but not with these results as before this the car had been burning oil through the PCV system but i have since fitted an oil catch can and that seems to have solved that problem as absolutely no smoke comes out the exhaust now bar steam when the engine is cold.

The garage was not very useful with providing a solution as they, naturally, wanted me to leave it at the garage to be fixed. Currently my theory is that the car is running very rich because of a lack of air getting into the combustion chambers as I've already tested the front heated lambda sensor and the voltage was within the range it should be, I've also taken a look inside the catalytic converter and that's fairly clean. I assume that if the fuel mixture is rich than it must be on the air side of the ratio as the car isn't putting out any black smoke which it apparently would be if the fuel was rich on the petrol side of things.

Anyway my main question is: What would be the best way to diagnose if the fuel mixture is rich or not and if it is, where is the best starting point on diagnosing the which part is at fault?

Just as a side note, there are no diagnostic codes stored in the car, but I do have a check engine light on and a "Reduced Engine Performance" note on the dashboards display. I also made a post about whether it was the catalytic converter here: www.reddit.com/r/mechanics/comments/789f5b if that helps

Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - RobJP

Those numbers, it sounds like the cat has probably failed.

Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - Ross Nicolai

I forgot to say that emissions actually passed on the idle test. If the cat had gone wouldn't the emissions be through the roof at idle aswell?

Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - RT

It's running in limp mode - I'm surprised they even started the emissions test with the Engine Light on - you need the full diagnostic codes read on proper equipment, not a universal scanner - then reset the codes, run the engine and see what new codes arise.

Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - elekie&a/c doctor
I guess this car has the Ford engine.These are notorious for oil burning and would think the cat has been swamped with oil.Dont think this will be an easy fix.
Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - elekie&a/c doctor
At fast idle , the cat has to process a lot more exhaust gas,if it is inefficient,then the emissions will be wrong.
Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - SLO76
I guess this car has the Ford engine.These are notorious for oil burning and would think the cat has been swamped with oil.Dont think this will be an easy fix.

It's a duratec motor which is just a Mazda L series with another name. Wasn't aware of any oil burning issues on these. Is this right enough?
Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - Railroad.

You need a suitable scantool to view the fuel trim data. Ideally the Short Term Fuel Trim should be ranging either side of zero, and the Long Term Fuel Trim should be fairly stable at somewhere close to zero. If your engine is running rich then this will be confirmed by a high LTFT percentage figure.

Volvo S40 - 2007 Volvo S40 1.8 Petrol - Emissions Through the - Railroad.

Sorry I meant a high negative percentage figure, indicating that the ECM is reducing injector duration to correct the rich mixture.

 

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