Good day to all,

I have recently been handed over my mothers 2014 ecoboost 1.0l Fiesta to be fixed since it failed its MOT on emissions, the emissions tester they used claimed the car was running at Lambda 0.70 on idle, which as a engineer that calibrates ECU's/Engines made me jump to the conclusion their tester was duff. It infact was not...

Upon plugging into it with Forscan and monitoring the ECU during an idle and drive it was reporting lambda readings between 0.69-0.80 during idle events when it was running in open loop mode (during starting, coming down from throttle/driving state, etc). I have replaced the Primary Wideband O2 Sensor with a known good and tested Bosch unit (I even tested the Original sensor - which was healthy) but to no avail (Still running pig rich). When the car returns to closed loop fueling control (at idle) the long term fuel trim sits anywhere from -35% to -45%, temperature and previous use case dependent (Negative fuel trim). 

Under normal driving conditions the engine/car drives fine with lambda returning to more reasonable levels, leading me to believe that it may be the fuel system (Pumps, injectors, etc) at fault rather than a bad MAP/MAF sensor? I took the plugs out and cleaned them, started the car again and let the car idle to a couple of fan cycles, then took the plugs out, behold all 3 plugs sooted up to hell. This has lead me to ruling out the injectors as surely all 3 cannot fail in such way all at the same time? 

I wish to get this fueling issue resolved and the car MOT'ed again as my sister is desperate for a car since hers failed its MOT in a disgustingly good way... (Key word, rust)

I am asking politely if anyone could be a bit of help via either experience of similar or just general higher familiarity with the workings of these little motors! (the only Direct injection fuel systems I've ever dealt with are that of Jap/German diesels). I have attached Forscan logs of what was a typical commute to work for me (Bit of a road, bit of B and some minor town driving) 

Logs here: https://www.dropbox.com/t/l0GtZv64hxiFpx4j

 

 

Many thanks everyone!

(Sorry for the long post, I never have been good at condensing information...)

I am surprised it can run this rich without the engine light or any fault codes.

I agree that all 3 injectors are unlikely to fail in the same way at the same time.  So that would suggest to me that the high pressure fuel pump is providing too much pressure.  It contains a small pressure regulator, however it cannot be replaced separately, so you would have to replace the pump & regulator together.  As a part that doesn't fail very often, I'd be tempted to try a used one from another car, can be picked up for around £25 from breakers yards.