Hi All.

First mistake...vehicle is a 4 not a 3 pot. Anyway same fault code extracted PO 0170 (Fuel trim) and stft at 25% and ltft at -0.8% with no running faults. Did not start car because I wanted to remove pre-cat ho2 sensor and clean (very sooty). Started car and during warm up noticed pre-cat HO2 sensor not switching but stuck at 0.035v with stft remaining at 25%. Post Cat sensor reading normally at 0.46v. Engine sounded too lean which I expected with those readings. No air leak was found. Eventually (engine hot) HO2 sensor burst into life and STFT dropped to -2% and high 02 content dropped from 3.8% to 0%. CO2 rose from 13.8% to 16.8% (from memory). CO and HC remained at 0 during this process. As far as adaptations are concerned, have been advised today that this is not required for a car of this vintage, so we have conflicting opinions on that subject. Anyway, would welcome opinions from people who know better than me. Unless I hear to the contrary, will be changing O2 sensor next when I get the call.

Regards

Pete M