OUR 1997 Hyundai Sonata V6 Auto has done 110,000km. It has been an excellent car, apart from a flat spot when accelerating. Fuel consumption seems heavy -- about 13 litres/100km around town and 10 litres/100km on a trip. My mechanic says all the numbers are perfect. He suggested using Caltex Vortex to minimise the flat spot, but it didn't have any effect on fuel consumption. What are the fuel ratings for the car, and what do you suggest to overcome the flat spot and consumption problems?
THE Sonata uses regular unleaded, but some Hyundai mechanics suggest running PULP occasionally to aid clean running. For the flat spot, check that the spark plugs were changed at 90,000km as recommended. The Hyundai uses platinum-tipped plugs and, because the inlet manifold has to be removed to change plugs in the three rear cylinders, mechanics have been known to leave them. They should have been replaced at 90,000km. Also check the plug leads.
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