Jean-Eric Vergne admits Toro Rosso have "major" issues having spent yet another day of testing stuck in the garage.
In action on Saturday, the fourth and final day in Bahrain, Vergne managed just 19 laps as his Toro Rosso mechanics and their Renault counterparts spent the bulk of the day attempting to his STR9 going.
With engine issue and other "teething problems" hurting Toro Rosso, Vergne finished Day Four's running down in eight place, 6.554s off the pace.
"There's no point in making negative comments, because everyone knows we are facing major problems and we are not alone in that," he said.
"We knew when we came to Bahrain that there had not been enough time since the previous test to have solved all our issues.
"On the positive side, we have managed to fix some of them now."
The Frenchman was complimentary of the STR9 when it did get going, confident that it will be a good package when it works.
"Even if I have not done so many laps, it's clear from those I have managed to complete, that Toro Rosso has done a good job to give me a car that feels nice to drive, if we talk about the elements that used to be the main topics before this year, such as the aero and mechanical side of the package.
"It's frustrating, but we need to keep calm and not get stressed as there are still a few weeks before Melbourne.
"We will try again here in Bahrain starting on Thursday. Clearly, in Melbourne, just finishing the race will mean you have a good chance of scoring points."