Kimi Raikkonen says he cannot explain why he is struggling to be consistent driving Ferrari's Formula 1 car this season.
The 2007 world champion has found it difficult to consistently match team-mate Fernando Alonso since rejoining the Scuderia for this year.
The Finn matched Alonso in the first part of qualifying for the Canadian Grand Prix, but ended up four tenths adrift come the end of the session.
He also ran right with the Spaniard during the first part of the race, but finished nearly 40 seconds adrift at the flag, including a quick spin at the hairpin.
Raikkonen reckons the car feels different from lap to lap, making it difficult for him to be consistent through a race.
"It's very difficult to really understand what is going on," Raikkonen said, when asked by AUTOSPORT whether the balance of his car shifted through a race.
"It seems to change. It can feel very difficult one lap, then suddenly for some reason a few laps later it's like the tyres work better.
"I cannot explain the reason, otherwise we would know. At the end of the race it seemed to be OK again. We have to look into things.
"There is potential in the car and the package. We have to just find out what we can do to get it on every lap."