Red Bull designer Adrian Newey went back to his drawing board on Thursday after another nightmare day for the Formula One champions in pre-season testing in southern Spain.
Australian Daniel Ricciardo, who has replaced compatriot Mark Webber as quadruple champion Sebastian Vettel's team mate, broke down on his first lap of the day and managed only two further circuits before Red Bull called time.
Vettel flew home from Jerez on Wednesday night after managing only 11 laps in two days following battery problems with the new Renault power unit. The team said Thursday's issues were similar to the previous day's.
"Adrian has gone back to the drawing board. There is only so much they can do here at the track," Ricciardo told reporters.
"Adrian is pretty happy working in his office back at Milton Keynes and he'll definitely be getting involved in trying to sort out the next step."
Newey, who has designed title-winning cars for three separate teams, actually has an old-style drawing board in his office that he likes to work on with a pencil and jokingly refers to himself as the last of the dinosaurs in a computer-generated age.
He has a real challenge on his hands now, with Formula One undergoing the biggest technical transformation in a generation with a new turbocharged V6 and complicated energy recovery systems as well as revised aerodynamics rules.
Ricciardo said time was still on Red Bull's side, with the team making slow starts to a season in the past only to end up dominant.
Vettel won the last nine races of 2013, a record for a single season, and 13 in total as he wrapped up a fourth successive title with three races to spare.
Red Bull's race-engineering co-ordinator Andy Damerum said the team had worked hard to make changes overnight but the measures taken had only partially solved the issues.
"It's obviously not where we want to be and naturally the whole team is frustrated by these issues," he said. "However we're pretty good at bouncing back from this type of thing."
While the Renault-engined teams struggled, with Toro Rosso managing only 30 laps after none on Wednesday and Caterham failing to set a timed circuit, those with Mercedes and Ferrari units racked up the mileage.
Danish rookie Kevin Magnussen was fastest overall on the third day with a lap of one minute 23.276 seconds in his first experience of the car he will be racing this year.
Brazilian Felipe Massa was second quickest for Williams, now powered by Mercedes after a switch from Renault, with 2008 champion Lewis Hamilton third on the timesheets for the Mercedes team and Jenson Button fourth for McLaren.
Ferrari's Fernando Alonso made his first appearance of the year in front of his home fans and completed 58 laps/257km with the fifth best time.
"I've missed it for a few months now, even if I've spent hours in the simulator in Maranello, and the feeling I got from the track was as exciting as ever," said the Spaniard.
"Now we have a lot of work ahead of us but we have a very big potential to make progress and that's encouraging."
Even if times were irrelevant, the time on the track was significant with cars with Mercedes power units completing a total of 965km so far and the Mercedes works team accounting for 783 of them.
"At the moment we're definitely happy," said Hamilton whose day was cut short by a transmission failure in the afternoon and who now hands over to team mate Nico Rosberg for the final day.
"I'm feeling very positive after these tests and every day on track is another step forwards."
Marussia made their track debut with Britain's Max Chilton at the wheel and did five installation laps as they dialed in the MR03 car.
"The laps we were able to complete were without issue so we are pretty pleased with the start we have made," said chief engineer Dave Greenwood.
(Editing by Tony Jimenez)