Pre, its a '98 theres only one bank. Fixed an 03 clio that had a goosed upstream o2 sensor that was causing a lean misfire but symptoms were totally different as the car runs fine on light throttle, its mainly the pinking thats the only symptom (I put the poor start down to the HG).

Every engine is different (from manufacturer to manufacturer) so not so sure if just the HO2S is causing pinking.

Reason for the MAF was that I thought it could be the only thing causing the ECU to advance the timing so much.