So the issue in hand is a 1st gen RS225 that seems to lack some power and has a slightly shaky idle. The car once lit up a fault code that turned out to be U0122 - Lost communication with vechile dynamics control (VDC) module. The car is my friends, but i am helping him fixing the issue since i have some experience in these things. My car is a 2010 mk2 Focus RS, and i was having similar issues a while back, which in the end was sourced from a fault in my car's software as it was mapped. I am kind of thinking my friends cars issues could be in a faulty MAP sensor or vaccum leak. Usually vaccum/boost leaks can be seen instantly in high LTFT-numbers, so my question is basically what LTFT numbers should a healthy RS225 run? After a very brief drive around the block the LTFT went up and down between +7 and +9%. Any other suggestions to the possible culprit of this issue are also welcome.
Mine LTFT sits now between 3,5% and 8,5%, when my fuelpump failed [3.0 bar instead of 3,5 bar @ the rail] LTFT readings was then 24% and 34% and no check engine light.
My friends car can't seem to settle on a steady LTFT. It jumps between +5% to -18,5% constantly with around 5 to 10 minute intervals. Is there any way of calculating AFR numbers on one of these? My OBD-scanner shows commanded equivalence ratio on my Focus RS, but not on the Megane. CER is used to calculate AFR as you probably know.
