LONDON, England - Most of the engine problems suffered by Renault-powered cars at the season-opening 2014 Australian F1 GP have been resolved, the automaker said on March 25 ahead of the next race in Malaysia.Renault supplies current F1 champion team Red Bull, its sister team Toro Rosso, Lotus and Caterham with the new V6 turbocharged petrol/battery 'power units'.Of the four, only Toro Rosso scored points in Melbourne; Red Bull's four-times Drivers' champion Sebastian Vettel retired after a handful of laps and his Australian team mate Daniel Ricciardo was disqualified from second place for excessive fuel flow.That decision is still under review.'SEVERAL ISSUES'None of the Lotus and Caterham cars lasted long enough to see the chequered flag.Renault Sport F1 track operations head Remi Taffin said in a preview of Sunday's race at Sepang that his company was optimistic of a better showing two weeks on."We had several issues across the cars in Melbourne but have recreated the problems on a dyno. Most are fixed, the others will be under control by Friday in Sepang," the Frenchman said. "We anticipate further issues may occur but can now react quickly to minimise their effect."Taffin cautioned, however, that Sepang would be far tougher on the new engines than it was on theV8 engines that were pensioned-off in 2013."In the V8 era the circuit sat towards the middle of the table for the challenge it posed for engines. Now it will be one of the toughest races of the year," he explained. "The humidity in Sepang made it a little bit easier on normally aspirated engines since power comes down as the water content in the air increases."This means we were generally able to offset the effect of the two long straights. This year we won't have this luxury. With a turbocharged engine the air intake is controlled at all times regardless of ambient conditions so those long straights will really start to hurt."Both straights at Sepang are more than a kilometre and will see the turbo revving at close to 100 000rpm for more than 10sec on each. Pressures within the combustion changer are almost twice as great as the V8.High ambient air temperatures will make choosing the right cooling level crucial.Stay with Wheels24 for the 2014 Malaysian GP.