I have an EB2 Fairmont. I just replaced the head gasket and the timing gear. Since the car has been back in the road it has been going through a lot of fuel. The trip computer stays at about 18 litres / 100 ks. It used to be about 14. It seems to be accurate as I put about 20L in and get just over 100ks. The car seems to be running sweet. Starts easily and idles well and has good performance. The only thing I thought it could be was the oxy sensor as it was running around with a blown head gasket for about a week before it was replaced and going through about a litre of coolant every 20ks. It was leaking into no.1 cylinder. I replaced the oxy sensor about 2 year ago for a similar reason but last time it it was blowing black smoke at any more than half throttle. this time you can use full throttle and it doesn't blow any smoke. Is it the oxy sensor??

well check that is is going into closed loop check voltage from it.
also would be a good idear to reset ur ecu to.

I havn't checked the closed loop voltage but I reset the ECU but it made no difference. I wil check to closed loop voltage tomorow

Ok, I did the oxy sensor test and it doesn't seem to go into the closed loop mode. The voltage on the test terminal stays at .55v and just stays there even after 5 minutes. From what I understand this is default mode and would be running as if the engine was cold. The engine temp sensor is working fine, so its not that and the fuseable link for the oxy sensor is ok. Looks lik I am up for a new oxy sensor.