Jenson Button was left frustrated after losing track time in Bahrain on Friday especially as his car was set-up "quite differently" to Fernando Alonso's.
The 2009 World Champion spent most of Friday afternoon's session in the McLaren garage as an electrical problem resulted in a spin on his third lap.
With his mechanics working furiously on the issue, Button also sat out the opening minutes of FP2 but did eventually make it out onto the track.
His running, though, was cut short after three laps when he pulled over when McLaren noticed an anomaly with his car's data.
Again the car was returned to the pits and again his mechanics managed to get him back out onto the circuit.
Button managed 15 laps in total on Friday night with his 1:39.209 leaving him languishing down in 19th place.
"The guys worked really hard, from P1 to P2 they did a great job but we still had our problems in P2," he explained.
"I went out on the soft tyre but had to quickly come back in, and then I went out on low fuel when everyone else was on high fuel, so it was difficult to get in any running. Overall not a great day.
"There was a lot of useful data from the other car, but the frustrating thing is our cars were set-up quite differently to get a lot of useful information about parts, and we weren't able to do that on our car.
"It doesn't help either of us for Saturday but hopefully we've resolved the issues I've had."
Looking ahead to Saturday's qualifying, the Brit expects another trying day for McLaren as those ahead up the power and the pace.
He told Press Association: "I think some teams were on high fuel all day as well, so it's not going to be an easy weekend.
"But we're not kidding ourselves, we know it's going to be a tricky qualifying session and I suppose for us at the moment we're going to qualify near the back.
"In reality it's not such a problem. The race pace is something that is more important."