The last tank full around Goolwa, on flat ground with good weather, returned 11 litres per hundred kilometres, previously it had been between 13 and 15. We had the air conditioner running most of the time and they tell me that can cost 1 to 2 litre per 100 k, so it looks like we are back to the expected performance for the Navara.
I have been complaining about the poor fuel consumption for the last 50,000 km, and despite several attempts Unley Nissan could not find anything wrong, even hinting it was my driving that was the problem. They reflashed the fuel pump twice ( at $130 a time), I have had it at a specialist diesel mechanic and finally at Turbo Tune. The Dyno results are shown in the graph. Killowat hours are shown on the left scale, indicating 15 Kilowatts missing, that's about 20 horses in the imperial system. On the right hand scale, using the lower set of graph lines, is the torque in Newton Metres. There is a big increase in torque at the lower rev range (bottom scale) which measures the pulling power when starting from stationary.
Total cost to find the problem-
Cost of investigations and resultant work about $1000.
Cost of excess fuel at 3 litre per 100k for 50000km at $1.50 per litre is $2250
Total cost is $3250.
Cost of cure is about $1 worth of electronic contact cleaner on the hot wire air flow meter.
It is worth a spray each time you change your air filter, it could save you from feeding 20 horses that are not doing any work!
