Unable to attend the team's final test for this event, Loeb took the same set-up as team-mates Hirvonen and Dani Sordo for this week's Villa Carlos Paz-based event, but could not find his rhythm with his Citroen through Thursday morning's opener.
"It's not 100 per cent with the car," he said. "After the first stage, I talked to the engineer and he told me I had to drive more in the style of Mikko, I had to be more aggressive with the car.
"This is not me, but I did it and the time was not so bad in the second stage."
Citroen engineer Cedric Mazenq said: "We found a couple of things new in the tests in Portugal and the one before this rally [the pre-event test in Sardinia] and Sebastien has never driven like this, which is why we pushed for him to modify his driving.
"These were not big changes, just a lot of details. He is beginning to understand how the car is working and he decided to leave the car for this afternoon.
"We saw in the first one [in the morning] he lost a little bit of time, but in the second one, he is already making the time."
Mazenq confirmed the team has the parts to change the DS3 back to Loeb's usual Rally Argentina set-up if he loses time on the afternoon loop.