My dear C70 has been putting constant town 20-19 litres/100 km (12 mpg) on the clock for quite a while now, so, I'm in need of you guys' expertise...
These days I decided to check the spark plugs (for the first time, since replacing with proper NGK Coppers), and re-gapped 'em to 0.28'', having reduced 1l/100km of the final count. There was a small amount of oil in the wells and in the screw, which I wiped, and there did not seem to be any white stains in the plugs heads. Then, upon checking my OBDII app, there seems to show a 5.0/4.5/6.0 constant "Timing Advance" data, and I cannot figure out why (you may have noticed I never performed a TB replacement in this car, for the last owner has).
For information purposes, this is the list of replacements I've performed: replaced Fuel Pressure Regulator (not Bosch, but 3.0 bar, factory spec unit), replaced Throttle Position Sensor, replaced Idle Air Control valve, replaced fuel pump and filter, replaced intake and intercooler hoses and cleaned intake housing, replaced rotor, distributor, ignition cables and spark plugs, replaced Mass Airflow Sensor and replaced the whole PCV system (cleaning PTC nipple included). Also gave a full 2 turns tightening to my wastegate actuator (which improved strongly the cars' response under throttle), though it does not seem to have altered the petrol mileage of the vehicle. Also replaced the struts/shocks and derived items, performing full alignment and balancing afterwards.
Could you guys help me with this annoying problem that has been emptying my student's pockets since I've bought the ole girl?
