Hi fellas, new here.

I have a 2004 Focus ST170. Just recently it's been throwing A DTC p1131 and has been stuttering and suffering from lack of power. I initially thought it might be a duff o2 sensor so had it replaced but the problem persists.
I invested in a bluetooth scanner and have logged some live data. It shows that once the car is started the rpm's are high at around 1600, and as soon as the car goes into closed loop the STFT will climb to around +35 and stay there in all rpm ranges. Once the car has been idling for a few minutes the stft will come back down to normal and the car will run and idle fine.

Whilst driving the car will start stuttering and feel like I'm driving into a strong headwind. At this time the stft's are high, but will drop again until the next time the car starts bucking and jerking.

I have no idea what is causing this so any help would be appreciated.

Cheers
Andrew

 

A common issue that causes this fault on the st170 is a fuel pump on its way out. Not an easy job to change either, tank out job!

 

Hey, thanks for the quick reply. Fuel pump was my first thought, but I bought this car off a neighbour who tells me he had the pump replaced 11 months ago with a brand new gen ford pump. So I doubt it is that now.