Malaysian GP: Problems for Renault in practice
The Renault cars did not immediately run in Friday afternoon practice while the team investigated the technical failures of the initial session at Sepang.
Team boss Eric Boullier confirmed at the Malaysian circuit that neither Nick Heidfeld or Vitaly Petrov would return to their R31s until the problem is understood and rectified.
"Best to be on the safe side," the team said on its official Twitter.
Heidfeld had returned to the pits in the first session with a blocked wheel, before Petrov spun into the gravel after a catastrophic failure on his left corner.
It was initially believed the problem was related to brakes, but the later theory was that the fault was in the suspension upright.
Half-way into the second session, it is believed the problem has been found and the cars will return to the track shortly.
Meanwhile, Boullier confirmed that German Heidfeld sat out some pre-weekend events this week with a throat infection.
"It's not serious," he told Bernama news agency. "He wanted to rest and be ready for free practice."
First Session: Webber fast at Sepang after Melbourne mystery
Mark Webber wasn't in a talking mood at Sepang when asked about his problems in Australia two weeks ago.
"We are not going to go into it too much," he told reporters. "I am not going to make a meal of what happened in Melbourne, so let's talk about Malaysia."
Red Bull team figures have said some minor issues were found aboard the Australian's RB7 in Melbourne, after he so struggled to keep up with his teammate Sebastian Vettel.
Team boss Christian Horner said the biggest potential issue was with a rear damper, but he insisted it is not the "smoking gun".
And according to Swiss newspaper Blick, the Briton dismissed an Australian media report that said a careless fan had leaned too hard on an aerodynamic part on Webber's car.
Instead, Horner said Albert Park is a "bogey circuit" for Webber and the team's blunt Helmut Marko told Auto Motor und Sport: "Mark had the pressure of his home race against a relaxed Vettel in super form."
Brazil's Globo reports that Red Bull decided to change Webber's chassis after Melbourne, and the Australian was fastest in the initial practice session at Sepang.